30-SECOND

ZOOLOGY
30-SECOND
ZOOLOGY
THE 50 MOST FUNDAMENTAL
CATEGORIES AND CONCEPTS
FROM THE STUDY OF ANIMAL LIFE

Editor
Mark Fellowes

Contributors
James Barnett
Amanda Callaghan
Peter Capainolo
Mark Fellowes
Neil Gostling
Rebecca Thomas

Illustrations
Nicky Ackland-Snow
First published in North America in 2020 by
Ivy Press
An imprint of The Quarto Group
The Old Brewery, 6 Blundell Street
London N7 9BH, United Kingdom
T (0)20 7700 6700
www.QuartoKnows.com

Copyright © 2020 Quarto Publishing plc

All rights reserved. No part of
this book may be reproduced or
transmitted in any form by any means,
electronic or mechanical, including
photocopying, recording or by any
information storage-and-retrieval
system, without written permission
from the copyright holder.
ISBN: 978-0-7112-5465-7
eISBN: 978-0-7112-5498-5
This book was conceived,
designed and produced by
Ivy Press
58 West Street,
Brighton BN1 2RA, UK
Publisher David Breuer
Editorial Director Tom Kitch
Art Director James Lawrence
Project Editor Stephanie Evans
Design Manager Anna Stevens
Designer Ginny Zeal
Illustrator Nicky Ackland-Snow
Editorial Assistant Niamh Jones
Printed in China
10 9 8 7 6 5 4 3 2 1
CONTENTS 44 Segmented Worms 110 Ecology
46 Arthropods 112 GLOSSARY
48 Molluscs 114 Profile: Robert May
116 Biogeography
50 The Vertebrates 118 Competition
52 GLOSSARY 120 Herbivory
54 Profile: Eugenie Clark 122 Predation
56 Chordates 124 Parasitism
58 Fish 126 Mutualisms
60 Amphibians 128 Keystone Species
62 Reptiles 130 Ecosystem Engineers
64 Birds
66 Mammals 132 Conservation & Extinction
134 GLOSSARY
6 Foreword 68 Physiology 136 Profile: Patricia Wright
8 Introduction 70 GLOSSARY 138 Climate Change
72 Profile: Donald Griffin 140 Habitat Loss
10 Origin & Evolution 74 Development 142 Pollution
12 GLOSSARY 76 Metamorphosis 144 Over-harvesting
14 Profile: Alfred Russel Wallace 78 Breathing 146 Invasive Species
16 Genes 80 Vision 148 Human–Wildlife Conflict
18 Natural Selection 82 Venoms & Poisons 150 Urban Animals
20 The First Animals 84 Flight
22 Phylogenetics & Diversity 152 Appendices
24 Mass Extinctions 86 Behaviour 154 Resources
26 Island Oddities 88 GLOSSARY 156 Notes on Contributors
90 Profile: E. O. Wilson 158 Index
28 The Invertebrates 92 Learning 160 Acknowledgements
30 GLOSSARY 94 Communication
32 Profile: Mary Jane West Eberhard 96 Managing Conflict
34 Sponges 98 Altruism
36 Jellyfish, Corals, 100 Group Living
Anemones & More 102 Mating
38 Echinoderms 104 Sexual Selection
40 Flatworms 106 Sperm Competition
42 Roundworms 108 Sex Allocation
INTRODUCTION
Mark Fellowes

Zoology, the study of animal life in all its forms and

structures, is a subject that has captivated people for millennia. In part,
this is for simple, practical reasons: animals are a source of food and
materials, and some of those we have domesticated also provide us
with their labour and companionship. Of course, other, wild, animals can
also threaten us with physical harm and disease. But animals are much
more than this; they are an innate part of our own species’ psyche. In
parts of France you can see cave paintings executed over 15,000 years
ago that depict species such as horses, bison and ibex in such detail
that even today they can be readily identified. But this is not something
unusual; everywhere across the world where we find ancient art we see
representations of animals, and this desire to identify with other species
remains a part of our culture.
The science of zoology has a long history, but we can think of it as
having two phases: what happened before Darwin and the exponential
growth in knowledge that occurred after him. The earliest surviving
systematic studies of animals were by the Greek philosopher Aristotle
(384 bce–322 bce). While living on the island of Lesbos he studied
the diversity of animal life around him, and he introduced key ideas
that influenced thinkers for many centuries, what we now think of as
metabolism, temperature regulation, sensation processing, embryonic
development and inheritance.
It was not until the Renaissance that Aristotle’s work was truly built
upon, with a renewed focus on the importance of empirical observations
in drawing conclusions about the natural world. This flowered after the
publication of Conrad Gessner’s Historia Animalium in the 1550s,
which was the first attempt to describe all known animal species. The
number of people studying animals grew, and taxonomists, such as Carl
Linnaeus (1707–78), attempted to bring coherence to our understanding
of the diversity of life, and great natural historians, among them John
James Audubon (1785–1851), signicantly expanded our knowledge of the
animal kingdom as they explored the world.
But it is the naturalist Charles Darwin (1809–81) who truly changed
zoology, just as he changed biology and beyond. In On the Origin of
Species (1859), he showed not only that species were not unchanging
but, more importantly, he provided a mechanism that explained how
that change could occur though natural (and later sexual) selection.
Zoology’s explanations for many of the wondrous forms and behaviours
of animals are based on his insights, and the great explosion in
zoological knowledge that followed Darwin truly placed our species’
history as being one among the animals rather than being somehow
separate from the rest of nature.
Zoology is not an arcane science; it is highly accessible, and an
understanding of zoology is central to our future. Zoologists apply
themselves to some of the most important challenges facing society
today: they study diseases that kill millions, such as malaria; they
investigate how to control crop pests, such as locusts, that can
devastate the poorest parts of the world; they help us to develop
ways to use resources, for example fisheries, sustainably; they develop
ecotourism projects to protect the last remaining great apes. But
zoologists also ask questions about the world and our place in it. Why is
biodiversity highest in the tropics? How do birds migrate with precision
halfway around the world? Why are some groups so rich in species,
whereas others only have one or two? Why do some animals use tools
and others do not? The former approach addresses urgent threats,
while the latter satisfies our innate curiosity.

Introduction g 7
 In this book we have focused on what we consider to be the 50 most
important concepts in zoology. Our aim is to we show just how broad,
fascinating and relevant the subject is as a science for the world today.
We start by considering the Origin & Evolution of animals, explaining
how the exuberant diversity of animal life came into being and how an
understanding of this helps explain some strange observations we see in
isolated islands. In the following two chapters we review the best known
of the major animal groups, The Invertebrates and The Vertebrates.
Then, in Chapter 4, we consider elements of Physiology, how animal
bodies work to allow them to adapt to different environments, covering
key concepts such as breathing and flight. In Chapter 5 we review key
concepts in Behaviour, that remarkable ability animals have to respond to
changes in their environments and to each other to enhance their chances
of surviving and reproducing. In the penultimate chapter we consider
Ecology, the science of how animals interact with each other and their
environments, determining their abundance and distributions. It is only
through an understanding of animal ecology that we can hope to mitigate
the challenges faced by animals in coming decades, and this is the topic of
our final chapter, Conservation & Extinction. Many zoologists would agree
that we are living through one of the greatest mass extinctions seen in
the history of the Earth, and there is little controversy over the realization
that the activities of humankind are the root cause. We over-exploit and
under-protect the great diversity of life on our planet, and if we are to
have any hope of protecting the most awe-inspiring of species in their
natural habitats, then we must act now. It is only by accepting our own
complicity in this devastation and then acting to mitigate it that we can
hope to ensure that future generations are as astonished by the grandeur
of animal life as we have been.
Life is truly precious. Let us resolve together to learn more about
these astonishing creatures, to love our environment and the myriad
animals it sustains, and to protect what remains for the generations
who will follow us.

8 g Introduction
 g
ORIGIN & EVOLUTION
 ORIGIN & EVOLUTION
GLOSSARY

analogous Referring to a characteristic clade A collection of organisms that group

derived by convergent evolution to solve together through the possession of shared
a problem, but not sharing evolutionary characteristics inherited from a common
history, such as the wings of birds and ancestor. Birds are an example of a clade.
insects.
conodonts Eel-like marine vertebrates.
bases and triplet code Specifically genetic
terms: DNA is composed of nucleotide convergent evolution The process that
bases A, C, T and G (U replaces T in RNA). allows common problems to be solved in
Bases in triplets (groups of three) specify similar ways, independently of evolutionary
the amino acid building blocks of proteins. relatedness. Flight in birds and bats has used
convergent evolution to independently turn
bilaterians Animals with three body axes: the arm into a wing in each group.
left–right, dorsal–ventral (back–front) and
anterior–posterior (head–tail). DNA The molecule that provides the chemical
instructions for making individual organisms.
central dogma (of molecular biology) DNA comprises four molecules: Adenine – A,
The DNA in the nucleus is copied, making Cytosine – C, Thymine – T and Guanine – G.
a molecule called RNA that provides the The order of letters provided the DNA code.
molecular instructions to make proteins.
eukaryotic The group of organisms that have
choanocyte The cells within a sponge that a defined nucleus that contains the DNA
have a beating flagellum surrounded by a homology/homologous: similar characteristics
collar (Gr. choana) that draws water and shared because of inheritance from a common
food particles through the sponge. ancestor, such as the forelimb in vertebrates.

choanoflagellates A group of single- flagellum (pl. flagella) A whip-like beating

celled organisms that resemble isolated structure, extending from cells, often
choanocytes of sponges. They are the enabling locomotion.
closest related single-celled organism
to animals.

12 g Origin & Evolution

genome duplication An episode in monophyletic group Organisms that included
tetrapod history, when all of the genes the last common ancestor and all of its
were doubled up, and then the entire descendants, living and extinct.
double set was doubled from 1 to 2 to 4
copies of genes found in invertebrates. niche The set of ecological requirements of
a species or population; it covers all of the
geological time A measure in eras aspects that a species needs to survive.
(for example, Palaeozoic, Mesozoic) and
periods (for example, Triassic, Jurassic, phylum (pl. phyla) The first taxonomic
Cretaceous) and defined by the fossils division of animals below the kingdom.
found in them. The changes in fossils, the
extinction events themselves, bracket protist A single-celled organism. There are
geological time periods. protist partners to all the multicellular
kingdoms: Plantae, Animalia and Fungi.
heterotroph An organism that obtains its
nutrition from ‘eating’ organic material. RNA The intermediary molecule that is the
same sequence as DNA (see opposite), which
homologous Similar characteristics shared provides the code that is translated into a
because of inheritance from a common protein. RNA substitutes Thymine for Uracil,
ancestor, such as the forelimb in vertebrates. and therefore has a ‘U’ in place of ‘T’.

industrial melanism Term to describe teleost A bony, ray-finned fish, such as the
the response that saw melanic (blacker) cod or goldfish.
varieties of species increase in response to
pollution causing a darkening of habitats, tetrapod A four-limbed vertebrate.
such as the trunks of trees.
transcription The act of copying the ‘ACTG’
K-T ME Abbreviation for the Cretaceous- code of DNA into the ‘ACUG’ code of RNA.
Tertiary Mass Extinction event,
approximately 66 million years ago, that translation The act of changing from the
saw the demise of the dinosaurs. ‘ACUG’ ‘triplet code’ of RNA into the amino
acid sequence in a protein.

Glossary g 13
 8 January 1823 1837 1854
Born in Llanbadoc, Usk, Wallace moves to London Embarks on an expedition
South Wales, to Thomas to train with his brother to the Malay Archipelago
and Mary Wallace to become a surveyor
18 June 1858
1844 Sends his paper on
1828 Takes up a teaching post natural selection to
Family moves to in Leicester, where he Charles Darwin
Hertford, England meets Henry Walter
Bates, an entomologist
1 July 1858
Darwin and Wallace’s
1848 work is presented to the
Aged 25, Wallace Linnaean Society, a year
accompanies Bates before Darwin’s own
aboard the Mischief for masterpiece is published
an expedition to Brazil
where he independently
collects many thousands 1869
of animal specimens Wallace publishes The
Malay Archipelago, an
account of his eight years
1852 in the region
Travels back to England
on board the Helen but
the vessel catches fire 1876
and sinks. Most of Publishes The
Wallace’s specimens, Geographical Distribution
drawings and field notes of Animals, which drew
are lost on his identification of
distinct biogeographical
zones

1881
Awarded an annual
pension by the British
government

7 November 1913
Dies and is buried in
Broadstone, Dorset

14 g Origin & Evolution

ALFRED RUSSEL WALLACE

Alfred Russel Wallace was an in the Moluccas that Wallace, suffering from a
unlikely character to rise to such prominence in malarial fever, had his epiphany about why,
the scientific world of the nineteenth century. across all of the islands he visited in Southeast
Born in what is now Monmouthshire, South Asia, there were unique species – just as Darwin
Wales, in 1823, the son of a solicitor of modest had done in the Galapagos.
means, he left school at the age of 14 and The parallel trajectory of Wallace’s and
followed his older brother to London. There he Darwin’s thinking later became apparent, and
trained as a surveyor, but other interests drew in their writings it can be seen how both men
his attention, and he became an amateur independently came to similar conclusions about
botanist. By the early 1840s he had left the the nature of nature. Wallace wrote his ideas
surveying business and spent a year in Leicester down in a paper, On the Tendency of Varieties
as a teacher. He briefly returned to surveying, to Depart Indefinitely from the Original Type.
but his passion for what would become the This, together with Darwin’s Extract from an
science of biology was developing in earnest. Unpublished Work on Species, was presented
Socially and politically Wallace was influenced to the Linnaean Society of London in 1858.
by the Welsh utopian socialist Robert Owen as In 1869 Wallace published his most celebrated
well as the great scientific writers of the time, book, The Malay Archipelago, which described
including the Prussian polymath Alexander von the eight years he had spent in the region.
Humboldt, Charles Darwin and the (originally) Central to his research was his description of
anonymous author of the 1844 natural history a biogeographical border – Wallace’s Line –
work Vestiges of the Natural History of between the islands of Bali and Lombok. Only 35
Creation (later revealed to have been written by kilometres (22 miles) apart, these islands belong
the Scottish evolutionary thinker and publisher to different biogeographical zones with differing
Robert Chambers). evolutionary histories: east are the flora and
Wallace’s contributions to science began fauna of Australia; west are those of Asia.
with expeditions to collect exotic animals and Wallace later withdrew from the public eye,
describe the biogeography of different parts but his contributions to science and natural
of the world. He travelled in the Amazon basin selection were recognized during his lifetime
(1848–52) and the Malay Archipelago (1854– – and the title of his 1889 volume on
62), where he collected over 100,000 specimens evolutionary biology gave us a term that
and described hundreds of new species. It was lives with us today: Darwinism.

Neil Gostling

Alfred Russel Wallace g 15

 GENES
the 30-second zoology
Genes are the DNA instructions
that produce organisms. Invertebrates have
roughly 10,000 genes, while tetrapod
3-SECOND DISSECTION vertebrates have about 25,000. This provides RELATED TOPICS
The ‘central dogma’ clear evidence of genome duplication, episodes See also
of genetics is DNA→ NATURAL SELECTION
where the number of genes in vertebrate
RNA→protein: a gene is page 18
transcribed into RNA,
lineages were exponentially increased. This idea
PHYLOGENETICS & DIVERSITY
which is translated into a was further supported by the discovery of a page 22
protein molecule that subset of genes called homeobox genes (Hox
performs a function within
for short), where vertebrates have four copies
the cells of living
of each Hox gene compared with invertebrates’ 30-SECOND TEXT
organisms. Neil Gostling
single copy of each. Hox genes express the
head-to-tail plan of all bilaterians (animals with
3-MINUTE SYNTHESIS three body axes) during embryonic development
Hox genes, and their
significance to the body
and indicate to cells their position in the body so
plan of organisms, were that regions develop the correct structures.
first discovered in the fruit Tetrapods have four times as many Hox genes
fly, Drosophila. If Hox
as invertebrates. However, gene number alone
genes are expressed in the
wrong place, the wrong does not explain why we are different from
appendage forms. This other animals. Humans have the same number
occasionally happens of genes as chimps, sharks, chickens and
naturally, and fruit flies
can develop legs where
snakes, whereas teleost fish, such as cod or
antennae should be. zebrafish, have twice as many as we do. How
In tetrapod vertebrates, genes are regulated, and the complexity of
the increase in Hox gene gene interactions, is far more important in
number provided the
genetic ‘toolkit’ for fins to
determining the complexity of the resulting
evolve into limbs and to organism than simply the number of genes
pattern the pentadactyl an organism has. Whether fish, fly or
hands that were used to
type these words.
human, there are genes
that provide a toolkit
form, building all
16 g Origin & Evolution animal bodies.
 NATURAL
SELECTION
the 30-second zoology
Natural selection is one of the
easiest mechanisms in science to understand. It
is the big idea that sets apart Charles Darwin’s
3-SECOND DISSECTION writings on evolution from earlier descriptions RELATED TOPICS
Individuals best suited of species change by scientists and natural See also
to an environment will GENES
philosophers. Evolution by natural selection
obtain resources, reach page 16
adulthood and be most
relies on three simple premises: first, resources
THE FIRST ANIMALS
likely to reproduce, are limited in nature so not all individuals can page 20
meaning that their survive to reproduce; second, individuals vary in
characteristics are passed
traits determined by the individual’s genetics,
on to the next generation.
which allow them to exploit those resources and 3-SECOND BIOGRAPHY
CHARLES DARWIN
survive; third, individuals with those traits are 1809–82
3-MINUTE SYNTHESIS more likely to reproduce and pass on the genes English naturalist and author
of many books, including On
Evolution is the which shaped those survival traits. It is as simple the Origin of Species (1859);
observed reality that life Darwin wrote some of the
has changed, and natural
as that. The environment is a filter, determining fundamental works that
which individuals, and therefore which traits, explain our natural world
selection is the mechanism.
Today’s living organisms make it through to the next generation. As the
have a single common
environment changes, the filter changes, so 30-SECOND TEXT
ancestor, which probably
evolved about 4 billion over time we see species adapt and evolve. One Neil Gostling

years ago. As environments example is industrial melanism. The peppered

changed, selective moth is typically white bodied with dark
pressures drove change in
speckles to camouflage it against tree trunks.
organisms. It might appear
that organisms are so With the advent of the Industrial Revolution,
It took a brain like
well adapted to their pollution covered tree trunks, exposing the
environments that there is Darwin’s to predict,
moths to bird predation. A rare dark form of
design and intent, but it purely on sight of an
is simply the result of less
the moth did well in these polluted habitats, orchid on Madagascar,
well-adapted organisms and it became dominant. As pollution controls that such flowers
not surviving or were introduced the dark form declined, as needed to be fertilized
reproducing as effectively
the environmental filter of soot-covered by a pollinator in
as those with a better fit.
trees was removed. possession of an
extraordinarily long
18 g Origin & Evolution proboscis.
 THE FIRST ANIMALS
the 30-second zoology
The first animals evolved from
their protist relatives, the choanoflagellates, over
700 million years ago. Choanoflagellates (from
3-SECOND DISSECTION ancient Greek choane, funnel) are peculiar single- RELATED TOPICS
Of the roughly 2 million celled organisms with a funnel-shaped collar See also
named animal species, GENES
surrounding a flagellum. They are normally
around two-thirds are page 16
insects (of which half are
solitary but sometimes form aggregations,
PHYLOGENETICS & DIVERSITY
beetles) and about 50,000 and they have the cell–cell adhesion and page 22
chordates, of which only cell-signalling molecules critical to the
about 5,000 are mammals. CHORDATES
multicellularity of ‘animals’. (Indeed, the page 56
choanocytes that line the inside of sponges look
3-MINUTE SYNTHESIS almost identical to them, highlighting the close
Dickinsonia, a 558-million- affinity that animals and choanoflagellates 3-SECOND BIOGRAPHY
year-old fossil of a large CHARLES DOOLITTLE
share.) As well as being multicellular, animals are WALCOTT
flat organism – variously
mobile heterotrophs, which means that they 1850–1927
described as a fungus and a American palaeontologist who
bacterial mat – has been obtain their nutrition from eating other things. discovered the Burgess Shale
Formation in British Columbia,
shown to have been an The Cambrian period (542–510 million years ago) Canada, in 1909; this is one
animal. In 2018 cholesterol
was a period of rapid diversification of animals. of the earliest fossil beds,
was isolated from these remarkable for the
fossils and, when analysed, Most of the phyla – the major animal groups preservation of the soft
parts of fossils
found to be a form that is alive today, including the chordates to which the
present only in animals. vertebrates (animals with backbones) belong –
The Cambrian phyla still
exist today, but animals
appear in the Cambrian fossil record. The 30-SECOND TEXT
extraordinary diversification has been put down Neil Gostling
were ‘experimenting’ with
body plans long before an to an ‘arms race’, as predators and prey
animal left its trackway developed more and more sensitive eyes,
542 million years ago
at the base of the
enabling them to hunt or avoid becoming prey,
Cambrian period. and skeletons to help in defence. The Cambrian
fossil record may, in fact, simply be a result of the By the Cambrian period,
evolution of fossilizable – that is, hard-bodied 542 million years ago,
– animals that had evolved some time earlier. almost all of the phyla
– a huge diversity of
20 g Origin & Evolution animals – were present.
 PHYLOGENETICS
& DIVERSITY
the 30-second zoology
Estimates suggest that there are
around 9 million eukaryotic species, of which
two million are animals, over half of them
3-SECOND DISSECTION insects. Mammals comprise only 5,000 species RELATED TOPICS
Phylogenetics, the study of and birds 10,000. The system of nomenclature See also
evolutionary relationships NATURAL SELECTION
– the naming of all organisms, formalized by
between species, combines page 18
genetics, comparative
the eighteenth-century Swedish scientist Carl
THE FIRST ANIMALS
anatomy and mathematics Linnaeus – remained the basis of biological page 20
with computing to build classification for over two centuries. His scheme
species’ family trees.
was hierarchical and without evolutionary
context; the concept of phylogeny arose with 3-SECOND BIOGRAPHY
CARL LINNAEUS
3-MINUTE SYNTHESIS Darwin’s theory of evolution. Phylogenies 1707–78
Phylogenetics is are produced by comparing shared derived, Swedish botanist and author of
based on shared derived Systema Naturae (1735) who
characteristics and
morphological and molecular characteristics and devised the binomial system of
classifying plants and animals
develops Darwin’s nested include an ancestor and all descendants, living
‘groups within groups’ idea and extinct. It seeks to classify all groups of WILLI HENNIG
of how species are related. 1913–76
organisms according to relatedness and is The father of systematic
Key to this is recognizing
homologous characters, concerned with clades, groups formed from a phylogenetics; his work helped
to bring taxonomy fully into an
derived by descent common ancestor of which all descendants form evolutionary framework,
something Linnaean
with modification. For monophyletic groups. Phylogenetics abandons classification lacked
example, the forelimbs of
some of Linnaeus’s hierarchy (species, genus,
vertebrates (fish fins, dog
legs, human arms and bird family, order, class, phylum, kingdom) to reflect
30-SECOND TEXT
wings) are homologous, evolutionary history. For example, the Linnaean Neil Gostling
the result of common class Reptilia is not monophyletic because the
ancestry. However, birds’
reptiles share their last common ancestor with
and bats’ wings, which Birds, mammals and
have the same function, both birds and mammals. Therefore, Reptilia is ‘reptiles’ reproduce by
are analogous, that is, not a group. However, this common ancestor, means of an amniotic
independently derived by dating back to the Carboniferous period
convergent evolution,
egg; they are common
enabling flight.
(330 million years ago), was the first animal to the monophyletic
with an amniotic membrane in its egg. group the Amniota,
whereas egg-laying fish
22 g Origin & Evolution and amphibians are not.
 MASS EXTINCTIONS
the 30-second zoology
Extinction is a fundamental part
of evolution. Over the past 500 million years
there have been five mass extinctions (MEs) and
3-SECOND DISSECTION many smaller events. The first, the Ordovician RELATED TOPICS
A mass extinction event is ME, 450 million years ago, witnessed large See also
when more than 60 per CLIMATE CHANGE
declines in marine life with the onset of global
cent of species disappear in page 138
less than a million years.
cooling. Thereafter, in the Devonian ME
HABITAT LOSS
(c. 364 million years ago) over half the marine page 140
genera – corals, vertebrates, trilobites and
3-MINUTE SYNTHESIS HUMAN–WILDLIFE CONFLICT
ammonites – disappeared, followed by the page 148
On the geological
timescale, mass extinctions
Permian ME (252 million years ago) when
are ‘sudden’ events, 96 per cent of species died out when widespread
but there is a natural volcanic activity caused rapid climate change. 3-SECOND BIOGRAPHY
MICHAEL BENTON
continuous process Insects suffered their only mass extinction 1956–
known as the background
extinction rate. Although
and trilobites became extinct, along with the British palaeontologist and
author of When Life Nearly
difficult to calculate, the dominant mammal-like reptiles. Their vacation Died, which describes all
aspects of the Permian ME
average lifespan of a of niches allowed another group of reptiles
species is 1–4 million years,
to radiate and evolve into the dinosaurs. A
but human activities are
estimated to be hastening further event at the end of the Triassic period 30-SECOND TEXT
(c. 200 million years ago) removed half of all Neil Gostling
the loss of plants and
animals to roughly a genera, including amphibians, reptiles and the
thousand times the
background rate of
conodonts. However, dinosaurs were able
extinction. The current to become the dominant terrestrial group
loss of biodiversity throughout the Mesozoic era, filling all niches
suggests that we are living and even taking to the skies. When an asteroid
through the sixth ME. Evolutionary history
struck Earth 66 million years ago, the event, has been punctuated
known as the K-T ME, wiped out the dinosaurs by mass extinctions.
and the vast majority of birds. One group, a relic The same events that
of the Permian, was then able to diversify and cause some species to
become the mammals we know today. become extinct provide
opportunities for others
24 g Origin & Evolution to evolve.
 ISLAND ODDITIES
the 30-second zoology
Islands do odd things to animals.
Insular life allows populations to exist in
splendid isolation from others of their kind,
3-SECOND DISSECTION but islands have limited resources, which results RELATED TOPICS
Species respond to in some peculiar evolutionary trajectories. See also
environmental conditions NATURAL SELECTION
Species that can best take advantage of their
or die out. On islands, page 18
where resources are limited
environment survive and reproduce. Where
PHYLOGENETICS & DIVERSITY
and predation reduced, the the new environment provides a reduced food page 22
adaptive response is often source or no predators, individuals whose
a radical change in size.
lineage reduces in size can survive on less
food or need not invest in growth to escape 30-SECOND TEXT
Neil Gostling
3-MINUTE SYNTHESIS predation. On Malta, for example, there are
It’s not only animals like fossils of a pygmy elephant that measured less
elephants, tortoises and than a metre at the shoulder. While island life
dodos that are changed by
island life. A lineage of tends to make large animals smaller, sometimes
Homo (likely H. erectus) small ones become bigger to fill a role. On the
was isolated on Flores, Galápagos Islands, where there were no
Indonesia, where they
mammals, tortoises became giants and the
became very small.
Discoveries made in dominant large herbivore. The dodo of Mauritius
2003 showed that the was a (very) large pigeon. Like many other birds
population of diminutive of isolated islands, it also stopped flying, which,
humans stood little more
than a metre tall. Their
like change in size, is also explained by trade-
isolation allowed them to offs. Flying is very energy intensive. If there
survive until 12,000 years is no advantage to flying, then it becomes a
ago, by which time our own hindrance. Individuals that do not invest in
species, H. sapiens, had
outcompeted all other flight can invest more in reproduction and so
human species across may have an advantage, and the ability to fly Selection pressures on
the planet. will be lost over time. Adapt or die. It’s the island-dwelling species
story of evolution. over evolutionary time
result in dwarfism in
some species and
26 g Origin & Evolution gigantism in others.
 g
THE INVERTEBRATES
 THE INVERTEBRATES
GLOSSARY

anthozoa Corals and anemones that have choanocyte The cells within a sponge that
the polyp form of cnidarian body plan. have a beating flagellum surrounded by a
collar (Greek. choana) that draws water and
bilaterians Animals with three body axes: food particles through the sponge.
left–right, dorsal–ventral (back–front) and
anterior–posterior (head–tail). clade A collection of organisms that group
together through the possession of shared
biomass The total quantity or weight of characteristics inherited from a common
organisms in a given area or volume. ancestor.

biosynthesis The biological process clitellum A thick, saddle-like section of a

whereby molecules are converted into more worm or leech in which eggs are stored.
complex products, often in a multi-step,
enzyme-catalyzed process. coelom The principal body cavity in most
animals, located between the intestinal canal
chaete (pl. chaetae) Body hairs or bristle. and the body wall.

chelicerataes The first pair of appendages coprolite Fossilized faeces.

on the head segment of a chelicerate.
ctenidium (pl. ctenidia) Comb- or feather-like
chemoreceptor A sensory cell or organ gills, part of the respiratory system of molluscs.
that can detect chemical stimuli, such as
smell or taste, and relay that information to cytotoxicity Meaning toxic to cells.
the central nervous system.
derived species A species possessing traits
chitin The material that forms the or features not found in its earlier ancestors.
exoskeletons of arthropods, the radulae
of molluscs, the scales of fish and some detritivore An organism that feeds on dead
amphibians and the beaks of cephalopods organic matter.
like the squid and octopus.
deuterostome Meaning ‘second stomach’,
this bilaterian group of animals shares an

30 g The Invertebrates
embryonic development plan and includes hydrozoa A class of small, largely marine,
chordates, echinoderms and hemichordates. invertebrates in the Cnidaria phylum.

ecdysis The process of moulting and kin selection Where workers are related to
replacing of the cuticle. Moulting is the offspring and hence increase their
necessary because the cuticle cannot evolutionary fitness by helping to rear siblings.
stretch as the animal grows bigger.
Lophotrochozoa A grouping of bilaterian
ecdysozoa A group of protostome animals animal phyla that includes molluscs and
that, in addition to the Arthropoda and annelids.
Nematoda, contains the phyla Tardigrada,
Onychophora, Nematomorpha, Priapulida, mesoglea A jelly-like substance without cells
Kinorrhynca and Loricifera. The name found in sponges and cnidarians.
ecdysozoa refers to their distinguishing
shared feature, a tough cuticle that is shed oligochaete A group of annelid worms that
as they grow. have few chaete (body hairs).

endoparasitic An internal parasite, one phylum (pl. phyla) The first taxonomic
that lives within the organs and tissues of division of animals below the kingdom.
a host animal.
polychaete A group of annelid worms that
eusocial/eusociality The most complex have many chaete (body hairs).
form of social behaviour observed in
insects such as wasps, ants and bees, secondary metabolites Organic compounds
which includes cooperative brood care that are not directly involved in the normal
within and across the generations and the growth, development or reproduction of
division of females into non-reproductive organisms.
workers and reproductive queens.
sessile Permanently fixed, immobile.
flagellum (pl. flagella) A whip-like beating
structure, extending from cells, often totipotent Capable of giving rise to any cell
enabling locomotion. type.

Glossary g 31
 1941 1988
Born in Pontiac, Elected member of the
Michigan, USA US National Academy of
Sciences

1963
Graduates from the 2003
University of Michigan, Publishes Developmental
Ann Arbor, with a BA in Plasticity and Evolution,
zoology wins the Hawkins Award
for the most outstanding
scholarly book of the year
1964
Receives MS in zoology 2009
from Ann Arbor Becomes Vice-chair of
the Committee on Human
Rights, National Academy
1967 of Sciences
Awarded PhD in zoology
from Ann Arbor
2012
Wins Quest Award for
1967–9 Lifetime Achievement,
Becomes post-doctoral Animal Behavior Society
researcher at Harvard
University
2018
Publishes paper in
Proceedings of the
1967–9
National Academy of
Takes up post of Research
Sciences of the United
Associate at University of
States of America, which
Valle, Cali, Colombia
suggests a link between
foetal growth conditions
and adult obesity and
1975– hence cardiovascular
Becomes Senior Scientist disease
at the Smithsonian
Tropical Research
Institute, Panama and,
from 1979, Costa Rica

32 g The Invertebrates
MARY JANE WEST-EBERHARD

Mary Jane West-Eberhard was Her work with social insects resulted in a new
born into a family who greatly encouraged her focus on phenotypic plasticity – the ability of a
curiosity, and through her engagement with a genotype to produce different phenotypes (forms).
4-H Club in high school (a US-based network While we commonly think of a genotype producing
of youth organizations supporting personal a single form, this is not always so. Consider
development) she was first introduced to aphids. For many species, if predators are around
entomology. While this did not immediately or if there are high levels of crowding, the normally
lead to a deep love of insects, this experience wingless forms can produce winged offspring,
was the key to part-time employment at the which can escape hazards and found new colonies.
Museum of Zoology at the University of West-Eberhard argues that such variation can
Michigan, which ultimately resulted in a career provide grist to the evolutionary mill. In 2003 she
working with insects. West-Eberhard studied published Developmental Plasticity and Evolution,
zoology at the University of Michigan, Ann which summarized her thoughts on phenotypic
Arbor, where she received her MS (1964) and variation and how this could affect the evolution of
PhD (1967). After two years of post-doctoral new species. This coincided with developments in
work at Harvard University, she started working molecular biology that resulted in the rapid growth
at the Smithsonian Tropical Research Institute of the field of evolutionary developmental biology;
(Panama), living first in Columbia, before moving her book pointed to the questions researchers
to Costa Rica, where she has lived since 1979. should be asking as they attempt to answer
West-Eberhard first came to prominence questions of adaptation and speciation using these
for her work on social wasps, focusing on the new ‘evo devo’ perspectives.
evolution of sociality. Wasps are eusocial – that More recently, she has used these perspectives
is, they have highly advanced social behaviours, on phenotypic plasticity to explain how poor foetal
with reproductive queens producing offspring diet results in increased adult obesity in humans.
that are cared for by non-reproductive females West-Eberhard argues that what is a beneficial
(workers). She was fascinated by the question defence mechanism in one situation (infancy),
of how such behaviour evolved, and argued turns out to cause one of the greatest global
that non-genetic factors influenced the causes of morbidity and mortality in our species.
evolution of eusocial behaviour in addition Zoology is often most controversial, and insightful,
to accepted explanations arising from kin when we take lessons learned from nature and use
selection theory. these to turn a lens on our own species.

Mark Fellowes

Mary Jane West-Eberhard g 33

 SPONGES
the 30-second zoology
Being immobile, sponges were at
one time thought to be plants, but they are, in
fact, animals consisting of relatively few cell
3-SECOND DISSECTION types arranged around a skeleton of tough RELATED TOPICS
Sponges, the sister group protein called spongin, a particular type of See also
of all other animals, are JELLYFISH, CORALS,
collagen. They possess only two layers of cells
multicellular animals that ANEMONES & MORE
lack respiratory, nervous or
separated by a layer of a jelly-like substance page 36
circulatory systems, organs called mesohyl. These primitive invertebrates ECHINODERMS
and body symmetry. have amazing regenerative properties thanks to page 38
totipotent cells called archaeocytes, which are
3-MINUTE SYNTHESIS
capable of generating all other cell types.
3-SECOND BIOGRAPHY
There are approximately Sponges are classed according to the type of ROBERT EDMOND GRANT
9,000 sponge species spicule (spine) of calcium or silica in their 1793–1874
worldwide, most of them Scottish anatomist, zoologist
skeletons: Demospongiae, the most diverse, and naturalist who discovered
marine, living attached to that water enters a sponge by
solid surfaces or, in some
which includes bath sponges; Calcarea, which small apertures and leaves at
species, the backs of crabs have calcium spicules; and Hexactinellida, or certain larger holes; he proved
that sponges are animals and is
that trade scraps of food glass sponges, which have silica spicules. It credited with the name Porifera
for protection. Sponges
might seem that sponges would be defenceless
feed using choanocyte cells
with flagella that beat the when threatened by predators or if competing
30-SECOND TEXT
water to create feeding for space, but they have an arsenal of chemical Amanda Callaghan
currents. Their scientific weapons that have cytotoxic, antibiotic and
name, Porifera, meaning
pore-bearer, refers to the
feeding-deterrent properties. These chemical
many pores through which weapons show striking structural similarities to
sponges absorb food and metabolites of microbial origin, suggesting that
oxygen and eliminate waste microorganisms are the true source of the
by means of a constant
flow of water.
metabolites or are intricately involved in their
biosynthesis. Sponges live in symbiosis with Sponges are a diverse
sometimes hundreds of different types of group of animals but
bacteria, and in some species bacteria constitute all possess the same
up to 40 per cent of their biomass. feeding system, which
is unique to the
34 g The Invertebrates phylum Porifera.
 JELLYFISH, CORALS,
ANEMONES & MORE
the 30-second zoology
The life cycle of Cnidaria – a phylum
that includes jellyfish, corals and anemones – is
remarkable, with multiple extreme changes in
3-SECOND DISSECTION body form. Depending on the class, they develop RELATED TOPICS
Cnidarians are radially between sessile polyps, swimming cup-shaped See also
symmetrical simple animals SPONGES
medusae, two kinds of free-swimming larvae and
distinguished by the page 34
presence of specialized
both sexual and asexual reproductive stages.
ECOSYSTEM ENGINEERS
stinging cells called Anthozoan sea anemones and corals lack the page 130
cnidocytes, or nematocysts, medusa stage and exist purely in the polyp form,
used for food capture
whereas the Scyphozoan jellyfish and hydra
and defence.
engage in the full multi-stage cycle. Cnidarian 3-SECOND BIOGRAPHY
RUTH GATES
bodies are essentially a sac with an opening 1962–2018
3-MINUTE SYNTHESIS serving as both mouth and anus surrounded by Director of the Hawaii Institute
of Marine Biology who studied
The name Cnidaria derives a ring of tentacles. In jellyfish the tentacles point coral bleaching and how, often
from the Greek word knide, as a result of warming seas,
meaning nettle. Cnidarians
down; in anemones and corals they point up. coral polyps lose their algal
Some jellyfish are a metre (39 inches) across with symbionts and eventually die
possess only two cell layers
– the ectoderm on the tentacles more than 10 metres (33 feet) long.
outside and the endoderm
Arguably the most spectacular cnidarian is the 30-SECOND TEXT
that lines the internal
cavity that forms the hydrozoan man-o’-war (Physalia), a colony Amanda Callaghan

stomach. Between the of genetically identical polyps and medusae that

layers is a cell-less jelly-like perform various functions, including that of an
substance called mesoglea.
All species of cnidarians are
inflated sail projecting above the ocean surface to
aquatic – mostly marine harness the wind. Hard coral polyps secrete a
The Cnidaria phylum
rather than freshwater – calcium carbonate sheath to house the living
and approximately 10,000 includes polyps, such as
animal, and most have a symbiotic relationship
species of jellyfish, soft-bodied anemones
hydrozoans, corals and
with photosynthesizing algae, zooxanthellae, and hard corals, which
sea anemones have so far explaining why hard corals are found in shallow are fixed to the sea
been described. waters. Corals are ecosystem engineers, building floor, and free-moving
vast reefs that house other organisms as well as medusae, including
forming a protective buffer between the sea and the many-tentacled
the coast. jellyfish and
36 g The Invertebrates man-o’-war.
 ECHINODERMS
the 30-second zoology
Echinoderms appear to be
radially symmetrical like a jellyfish, but, while
this is true in the adult form, they actually start
3-SECOND DISSECTION life as bilateral free-swimming larvae that go RELATED TOPIC
Echinoderms are the sea on to develop their characteristic radial See also
urchins, sea stars, brittle CHORDATES
(often five-sided) symmetry. This embryonic
stars, sea cucumbers and page 56
sea lilies and take their
development groups them with the bilaterial
name from the ancient deuterostome branch of the tree of life that
Greek echinos, hedgehog, contains the vertebrates like us. Echinoderms all 3-SECOND BIOGRAPHIES
and derma, skin. GEORGES CUVIER
possess rigid mesodermal plates called ossicles 1769–1832
made from calcium carbonate crystal. These French naturalist and zoologist
who established the scientific
3-MINUTE SYNTHESIS take a number of different forms, fusing to fields of palaeontology and
comparative anatomy; he was
Most echinoderms live on make an urchin test, loosely linking in sea stars the first to describe the sea
the sea bed, although sea or forming rings in sea cucumbers. Some species cucumber behaviour of
stars and sea urchins can expelling toxic threads
often be found in rock
are sessile filter feeders, but others, such as
ERNST HAECKEL
pools on the sea shore. urchins and sea stars, are ferocious mobile 1834–1919
A unique feature of predators, sitting on prey and exuding their German naturalist, zoologist,
echinoderms is their water physician and philosopher; he
stomachs and digestive enzymes through their was an extraordinary artist
vascular system. This is who discovered and named
a complex series of mouths. Soft sea cucumbers, which seem thousands of new species
channels that move vulnerable to predation, have an arsenal of
seawater through a pore weapons to fight back. They expel white, sticky,
called the madreporite to 30-SECOND TEXT
generate differential water
toxic threads called Cuvierian tubules from their
Amanda Callaghan
pressures. This moves their anus, which can entangle or even kill a would-be
hollow tube feet, pumping predator. If really annoyed they simply explode
them up and down like a their guts through their anus on to the predator
thin balloon.
and have to wait for them to regenerate. Sea
stars also have amazing powers of regeneration
and can regrow arms or even split their bodies The many-armed
into two separate animals. echinoderms are all
marine invertebrates in
possession of a spiny
38 g The Invertebrates shell or leathery skin.
 FLATWORMS
the 30-second zoology
Platyhelminthes – or flatworms –
are soft-bodied, dorsoventrally flattened worms
with no body segmentation. They lack a
3-SECOND DISSECTION through-gut, coelom, circulatory and respiratory RELATED TOPICS
Platyhelminthes are systems and are able to absorb oxygen and See also
bilaterian flattened worms SEGMENTED WORMS
nutrients by direct diffusion through their skin
that range in size from page 44
microscopic to several
– handy if you live inside other animals as most
MOLLUSCS
metres in length; many are Platyhelminthes do (including such well-known page 48
parasites while others species as the highly specialized tapeworms that
inhabit marine, fresh water
live in vertebrate guts). Adults are little more
or damp terrestrial habitats.
than gonads with a head full of hooks with 3-SECOND BIOGRAPHY
KARL GEGENBAUR
which they attach themselves to and feed from 1826–1903
their host’s intestines. Trematodes, or flukes, German comparative anatomist
3-MINUTE SYNTHESIS and strong supporter of the
are also parasites of vertebrates. The life cycle theory of evolution who
Placing Platyhelminthes on first coined the name
the tree of life has been
of most flukes involves being hosted by snails Platyhelminthes and divided
controversial and hindered and vertebrates. Larval forms released from the phylum into four classes

by the absence of a fossil infested snails into fresh water infect people
record, although fossilized
and animals, either by direct contact with water 30-SECOND TEXT
eggs were discovered in a
270-million-year-old shark or by eating undercooked fish, crustaceans Amanda Callaghan
coprolite. Modern analyses or poorly washed raw watercress. Not all
show that Platyhelminthes, Platyhelminthes are parasitic. The Turbellaria
molluscs and annelids share
a common ancestor.
includes non-parasitic, or free-living, flatworms
Platyhelminthes may have called planarians. These worms have a
evolved from a more remarkable ability to regenerate body parts by
complex ancestor, losing virtue of having retained specialized stem cells
such features as a
through-gut to adapt to
into adulthood. This is great for the worm but
an endoparasitic lifestyle. also for scientists in need of numerous Many flatworms, such
The few Platyhelminthes flatworms for research. Instead of breeding as tapeworms and
with a gut have no anus;
planarians they can simply cut these worms flukes, are happy to
they eat and excrete via
their mouths. up to generate a population to work with. inhabit the bodies of
other organisms – from
40 g The Invertebrates humans to snails.
 ROUNDWORMS
the 30-second zoology
Although the common name for
nematodes is roundworms, ‘worm’ is a
vernacular term related to their body shape and
3-SECOND DISSECTION is not an indicator of evolutionary relationships. RELATED TOPICS
Roundworms are Roundworms are on the same branch of the tree See also
unsegmented worms, ARTHROPODS
of life as arthropods in a clade called Ecdysozoa.
round in cross-section but page 46
tapered either end, that
Like insects and crustaceans, they shed their
SEGMENTED WORMS
occur in almost every cuticle to grow by a process called ecdysis. page 44
habitat, including inside Unlike arthropods, they lack the polysaccharide
plants and other animals.
chitin in their skin and instead have the animal
protein collagen, also found in human skin. 3-SECOND BIOGRAPHY
NATHAN AUGUSTUS COBB
3-MINUTE SYNTHESIS Nematodes have a well-developed body cavity 1859–1932
Nematodes are one of the with a complete digestive tube but lack American researcher, known
as the father of nematology
most abundant animals on respiratory or circulatory systems. They move in the USA, who identified
the planet and are of great more than 1,000 species of
economic importance, yet
with a characteristic wiggling S shape because nematode. He famously
they have muscles that run only lengthways commented that if everything
few people will ever have apart from nematodes was
seen one. Most nematodes along their bodies. Nematode heads can magically removed from the
are less than one millimetre planet ‘our world would still
have mouths with hooks, jaws or spines and be dimly recognizable … we
in length, but they are should find its mountains,
essential for soil aeration chemoreceptor sense organs. Many species are hills, vales, rivers, lakes, and
parasitic and are significant agricultural pests oceans represented by a film
and the recycling of of nematodes’.
organic and mineral of plants and veterinary and medical pests of
matter. Although only
animals – anyone owning a cat or dog will have
approximately 23,000
treated their pets with drugs to kill intestinal 30-SECOND TEXT
species have been formally
Amanda Callaghan
described, it is estimated roundworm parasites. Humans are also
that there are up to a susceptible to roundworm infestation, and
million nematode species Roundworms can live,
on the planet.
filarial roundworms, transmitted by mosquitoes, feed and reproduce in
can infect lymph nodes, passing on serious the gut without any
debilitating diseases such as elephantiasis, apparent symptoms in
which can cause legs and other extremities to the host, but where
swell to enormous proportions. they infest the lymph
nodes, serious diseases
42 g The Invertebrates can develop.
 SEGMENTED
WORMS
the 30-second zoology
Annelida – or segmented worms
– are an ecologically diverse phylum of animals
within the clade Lophotrochozoa. One annelid
3-SECOND DISSECTION group, the Clitellata – named for the mucus- RELATED TOPICS
Annelid worms are covered clitellum that provides a cocoon for See also
characterized by the ARTHROPODS
their eggs – includes blood-sucking leeches and
segmentation of their page 46
cylindrical bodies, which,
earthworms. Leeches have lost many annelid
MOLLUSCS
from the Latin word features and most use suckers to latch on to page 48
annulus, meaning ring, prey, cutting into the flesh with sharp jaws or
gives the phylum its name.
sucking through a proboscis. Oligochaete
earthworms burrow through soil feeding on 3-SECOND BIOGRAPHY
KATHARINE BUSH
3-MINUTE SYNTHESIS decomposing organic matter. Polychaetes, or 1855–1937
Because of their diversity, bristle worms, are by far the most abundant The first woman at Yale to
receive a PhD in the sciences;
annelids are found in a annelid group. These diverse and colourful her thesis was on the sabellid
huge variety of moist and serpulid polychaetes
habitats, including marine,
marine annelids range from one millimetre to collected by the Harriman
freshwater and terrestrial three metres (³⁄64 inch–10 feet) in length and Alaska Expedition of 1899,
which, as a woman of her
environments. Some include burrowing, crawling and sessile species time, she had been unable
species are suspension to join directly
as well as spectacular predators. Their segments
feeders, others are
detritivores, deposit have little paddles called parapodia, which are
feeders, scavengers, used for swimming or walking. One, the 30-SECOND TEXT
herbivores or carnivores. Amanda Callaghan
ferocious bobbit worm, can grow up to a metre
With at least 17,000
described species, annelids
in length and lies buried in the seabed with only
are so morphologically its sharp open jaws poking above the sand.
diverse that there is no one Bobbit worms have the strength and speed to
feature that defines them grab a passing fish and pull it down into its
all. However, most annelids
have segmentation,
burrow. Glycera polychaetes – bloodworms – are
bilateral symmetry, popular bait for fishermen. Their bite contains a From the fish-snatching
chitinous bristles called neurotoxin that causes uncontrollable muscle bobbit worm to the
chaetae and a hydrostatic
twitching, effectively paralysing prey. This common earthworm,
skeleton.
wouldn’t kill a human but can be very painful. the annelids populate
both marine and
44 g The Invertebrates terrestrial habitats.
 ARTHROPODS
the 30-second zoology
Arthropods first evolved in the
ancient seas around 600 million years ago, and
yet their most successful descendants are the
3-SECOND DISSECTION terrestrial insects. Insects, which evolved from RELATED TOPICS
Approximately 80 per cent crustacean ancestors, have three pairs of legs, a See also
of all animal species are ROUNDWORMS
head, thorax and abdomen, and most species in
arthropods, which makes page 42
them the most successful
the 27 insect orders have wings. They have filled
animals on the planet. almost every conceivable non-marine niche,
adapting to both endoparasitic and ectoparasitic 3-SECOND BIOGRAPHY
MIRIAM ROTHSCHILD
lifestyles and exploiting multiple food sources 1908–2005
3-MINUTE SYNTHESIS
including plants and vertebrate blood. Public Known as the ‘Queen of the
Arthropods (from ancient Fleas’, Miriam Rothschild FRS,
Greek arthron, jointed, and perception of insects is often negative, yet only was a self-taught world
authority on fleas, bees and
podes, feet) – which are around 3 per cent of insect species are pests butterflies. She discovered
grouped into the insects, and many, such as pollinators, are extremely that the life cycle of the rabbit
chelicerates, crustaceans flea, vector of myxomatosis,
and myriapods – are a
beneficial. Nearly all crustaceans, including was linked to the host’s sex
hormones. Famously she kept
hugely successful phylum lobsters, crabs and shrimps, live in salt or fresh live fleas in plastic bags in her
bedroom so that she could ‘see
of sophisticated animals waters; woodlice are the only truly terrestrial what they are doing and so
with well-developed crustacean. Crustaceans have exoskeletons children do not annoy them’.
respiratory systems,
sensory organs, a true hardened with calcium carbonate and a highly
body cavity (coelom) and a varied body plan, ranging from barnacles that 30-SECOND TEXT
protective and versatile cement themselves on to rocks to enormous Amanda Callaghan
exoskeleton made of chitin.
marine crabs. Myriapods, meaning many legged,
As members of the
Ecdysozoa clade they grow are the cylindrical millipedes and flattened
by shedding their cuticle. predatory centipedes. Chelicerates are the
They are extremely terrestrial arachnids (spiders, scorpions and ticks)
adaptable and are found in Arthropods are the
all environments and at
and the marine horseshoe crabs and sea spiders. most diverse of all
extremes of temperature, Most chelicerates have only two body parts – the animals on Earth. They
pressure and salinity. cephalothorax, a fusion of the head and thorax, include herbivores,
and the abdomen – and at least four pairs of legs. predators and
detrivores and occupy
terrestrial, aerial and
46 g The Invertebrates aquatic habitats.
 MOLLUSCS
the 30-second zoology
More than 80 per cent of all
mollusc species are gastropods, the snails and
slugs, which have a large foot that makes up
3-SECOND DISSECTION most of the visible soft flesh. Their shells tend RELATED TOPIC
Molluscs form a to be coiled or spiralled, and the body can be See also
very diverse group of SEGMENTED WORMS
withdrawn into it, although in some the shell
mostly marine animals page 44
characterized by having a
has been significantly reduced or even, as with
mantle that secretes slugs, lost completely. The 180-degree rotation
calcium carbonate for shell or twisting of their bodies during development, 3-SECOND BIOGRAPHIES
formation, a radula for JEANNE VILLEPREUX-POWER
called torsion, is a gastropod characteristic 1794–1871
feeding and gills (ctenidia).
resulting in an anus that is located above the French amateur naturalist
interested in cephalopods; she
mouth. Only molluscs have a radula, a specialized preferred to study live animals
and is credited with the
3-MINUTE SYNTHESIS toothed structure that is used to rasp food from invention of the aquarium
The molluscs (Mollusca) a hard substrate or bore into prey. Cephalopods,
form the second largest GEORG EBERHARD RUMPHIUS
animal phylum after the
such as the octopuses, have both a radula and 1627–1702
arthropods, comprising beak-like jaws, while cone snails have adapted German-born botanist who was
the first to publish a mollusc
around 80,000 described their radula into toxin-soaked harpoons that taxonomy and gave names to
species grouped into eight groups such as the gastropods
they can shoot at prey or predators. Bivalves and bivalves
extant classes. Most
people are familiar with the lack a radula and have instead adapted their THOMAS SAY
bivalves, snails and slugs, ctenidia into a net-like mesh to filter-feed from 1787–1834
octopuses and squid but American naturalist, known
the water. Cephalopods are intelligent marine as the father of American
have probably not come
across the other classes,
predators that are highly derived, with conchology, who collected,
studied and described many
which include worm-like prehensile tentacles, ink sacs and a muscular insects, molluscs and reptiles
forms and chitons covered funnel called a siphon that expels water for
in articulated plates. Some rapid movement. By contrast, many bivalves,
snail and bivalve species 30-SECOND TEXT
live in fresh water, but only
whose principal feature is their two-hinged Amanda Callaghan
the snails and slugs have shells, burrow into sediment or attach
managed to survive on themselves to objects on the seabed. Molluscs are soft-
dry land.
bodied invertebrates,
some of which
are encased in
48 g The Invertebrates a protective shell.
 g
THE VERTEBRATES
 THE VERTEBRATES
GLOSSARY

amniotes Term for the tetrapod endostyle A structure found in lower

vertebrates that either lay eggs on land chordates and larval lampreys that aids in
(birds and reptiles) or retain their fertilized filter-feeding.
eggs in the mother’s body (mammals),
which distinguishes them from egg-laying Hox gene A set of genes that codes for the
amphibians and fish. body plans of organisms.

anadromous Term describing fish, such as herpetologist One who studies amphibians
salmon, that leave ocean environments to and reptiles.
spawn in rivers and lakes.
ichthyology The branch of vertebrate zoology
binomial nomenclature The classification concerned with the study of fishes.
system whereby organisms are named
using a two-word identifier, the first being monotremes Odd, egg-laying mammals, such
genus and the second the species. as the platypus and echidna.

bioindicator A species or group of species notochord A stiff, dorsal rod running the
that indicate changes in the environment, body length of all embryonic vertebrates and
often by fluctuations in population number. some adult invertebrate animals.

caecilians Secretive, limbless tropical photobacteria A group of mostly marine

amphibians related to salamanders. bacteria that are bioluminescent (meaning
they have the ability to glow in the dark).
cephalochordates Small, segmented
invertebrate marine animals that possess placoid scale The small, hardened scales
a notochord (see below). made of enamel found on the bodies of
sharks, skates and rays.
endemic Plants and animals found in a
place. The term endemic can apply to a synapsids Ancient reptiles, the ancestors of
specific or a broad region. mammals, having one opening in the skull.

52 g The Vertebrates
tetrapodomorph Any four-limbed
vertebrate. The Tetrapodomorpha is a clade
that includes all four-limbed vertebrates
and their nearest sarcopterygian relatives
(lobe-finned fish), of which the coelacanth
is the only extant (living) species.

tetrapods Vertebrates with two pairs of

limbs. Tetrapods include all existing and
extinct amphibians, reptiles (including
dinosaurs and birds) and mammals.

tuatara Lizard-like reptiles that are

endemic to New Zealand.

tunicate A small, marine invertebrate

chordate, which feeds by siphoning water
in and out of its body.

urochordate A synonym for tunicate

(see above).

Glossary g 53
 4 May 1922 1946/1950 1953
Born in New York City, Receives MA and PhD First book, Lady with a
USA from New York Spear, is published; it
University; while recounts her experiences
undertaking her studies in the Pacific
1942 she conducted research
Graduates with at the Scripps Institution
Bachelor’s degree in of Oceanography in La 1966/1968
zoology from Hunter Jolla, California, the Teaches at the City
College, New York American Museum of University of New York
Natural History, New and University of
York, Woods Hole Marine Maryland, College Park,
Biological Laboratory, Maryland, USA
Massachusetts, and
also at the Lerner Marine
Laboratory in Bimini,
1969
Bahamas
Publishes The Lady and
the Sharks about her
work in shark biology and
1949 conservation
Studies fish populations
in Guam, the Marshall
Islands, the Palau Islands,
1999
the Northern Mariana
Retires from teaching but
Islands and the Caroline
continues to teach one
Islands
zoology course per
semester for many years

2000
Becomes Senior Scientist,
Director Emerita and
Trustee at Mote Marine
Laboratory, Sarasota,
Florida, USA

25 February 2015
Dies at the age of 92 in
Sarasota, Florida, USA

54 g The Vertebrates
EUGENIE CLARK

Eugenie Clark seemed destined Among her discoveries was the fact that,
to be a marine biologist. During her grade- and contrary to what was believed at the time,
high-school days in New York she often wrote sharks need not move to breathe oxygen –
reports about marine life for her assignment although this myth persists today. She
topics. She visited the aquarium every Saturday conducted experiments where she was able
and was mesmerized by the life and careers to train sharks to perform simple tasks,
of famous marine scientists and explorers. indicating that they possessed intelligence
She decided early on that her life goal was to and were not just simple eating machines.
become one. Concerned that sharks were being unfairly
She applied to Columbia University for persecuted because of their reputation,
postgraduate study, but, being married with Clark gave public lectures on shark behaviour
small children, her application was rejected as as well as working to develop many television
it was assumed she would leave to focus on specials on marine conservation. She also
family. Instead, she earned her MA and PhD made over 70 dives in a submersible, a little-
degrees from New York University. known technology at the time. Of her many
Under an Office of Naval Research accomplishments, developing scuba equipment
programme to undertake scientific research as a research tool is significant, and she
in Micronesia in 1949, Clark studied fish received numerous awards and honours,
populations in the Pacific. She also conducted including three honorary degrees, in recognition
ichthyological studies at the Marine Biological of her many contributions to marine biology
Station in Hurghada, Egypt, where she and conservation.
discovered that one fish, the Moses sole, Perhaps the greatest distinction for a
exudes a natural shark repellent. Her first zoologist is to have a new species named in
book, Lady with a Spear (1953) – which recognition of their work, and Eugenie Clark,
recounted her experiences while conducting popularly known as ‘the Shark Lady’, had
this work – met with acclaim and inspired many, including Callogobius clarki, Sticharium
financial backers to fund her research, and she clarkae, Enneapterygius clarkae, Atrobucca
remained a prolific writer throughout her career, geniae and, notably, Squalus clarkae – also
authoring some 175 scientific articles. known as ‘Genie’s dogfish’.

Peter Capainolo

Eugenie Clark g 55
 CHORDATES
the 30-second zoology
Chordate bodies vary widely in
form, but all are stiffened by a close-packed
cylinder of cells within a toughened membrane
3-SECOND DISSECTION called a notochord. In vertebrates the notochord RELATED TOPICS
Chordates are a diverse is replaced by the vertebral column, or spine. See also
phylum of animals that GENES
Chordates have a dorsal nerve cord and, at some
vary from mat-like sea page 16
squirts on the undersides
stage in their lives, most have longitudinal
ECHINODERMS
of rocks to dynamic and muscles along the length of the body. These page 38
(usually) intelligent move against the stiffened notochord or
humans. FISH
vertebrae, allowing animals to bend and become page 56
highly active. If you were to draw a basic
3-MINUTE SYNTHESIS chordate, it would probably resemble the tiny
Chordates are grouped with fish-like marine animal called a cephalochordate, 3-SECOND BIOGRAPHY
PETER HOLLAND
the Hemichordata and also known as a lancelet. These are important 1963–
Echinodermata phyla.
Hemichordates are worm-
animals to developmental biologists who have British evolutionary biologist
and zoologist whose research
like marine animals that are studied their Hox genes as an example of an focuses on how the evolution
of animal diversity can be
split into Enteropneusta ancestral form. However, cephalochordates are explained through the
(acorn worms) and evolution of the genome
not our ancestors. Perhaps surprisingly,
Pterobranchia (colonial sea
angels). They share some molecular analysis has revealed that the
features with Chordates, urochordates, also known as sea squirts, are 30-SECOND TEXT
which are divided into three more closely related to vertebrates. These Amanda Callaghan
groups: the urochordate
tunicates, cephalochordates
sac-like animals appear to be simple creatures
and vertebrates. Primitive that filter feed through two main siphons.
Primitive chordates,
chordates have an However, it is in their free-swimming larval form
endostyle, an organ at the such as sea squirts and
that their heritage becomes obvious, with a
base of the pharynx that lancelets, mark the
secretes mucus used for
notochord, nerve cord, pharynx and post-anal transition between
feeding. In vertebrates tail. The remaining Vertebrata group is known as invertebrates and
this has disappeared and Craniata, since all have a bony or cartilaginous vertebrates. The
been repurposed into the
brain case but not all have vertebrae. lamprey is a living
thyroid gland.
example of an ancient
lineage of jawless fish
56 g The Vertebrates that preceded true fish.
 FISH
the 30-second zoology
Spanning 60 million years, the
Devonian is known as the ‘Age of Fishes’
because of the wide diversity of major fish
3-SECOND DISSECTION groups found in fossils from the period. Sharks RELATED TOPICS
Fish display a remarkable and rays of all sizes – which have skin covered See also
diversity and represent an EUGENIE CLARKE
by placoid scales and a skeleton composed of
important evolutionary page 54
transition of vertebrates
cartilage rather than ossified bone – were
AMPHIBIANS
from aquatic to terrestrial abundant, and their descendants still hunt in page 58
environments that the world’s oceans today. Also first appearing
occurred c. 390–360 million
in the Devonian oceans were the bony fish,
years ago.
or Osteichthyes. As the name suggests – and 3-SECOND BIOGRAPHIES
PETER ARTEDI
unlike sharks and rays – the skeletons of bony 1705–1735
3-MINUTE SYNTHESIS fish are made of bone, and their scales are of Swedish naturalist, known as
the father of ichthyology; a
Ichthyologists have no variable shape and composition depending on colleague of Carl Linnaeus who
shortage of fascinating formalized the system of
phenomena to study.
the species. Most of the approximately 28,000 binomial nomenclature
Catfish and sharks possess species of fish currently known to science are
MARJORIE EILEEN DORIS
organs that detect electric Osteichthyes, and they are divided into two COURTENAY-LATIMER
current emanating from 1907–2004
classes: the Sarcopterygii, or lobe-finned fish,
aquatic life forms. South South African museum curator
American knifefish produce and the Actinopterygii, or ray-finned fish. who discovered a specimen of
an extant Sarcopterygian fish,
electric currents for The Sarcopterygii are important evolutionarily, the coelacanth, in 1938
navigation and social as they appear to be ancestral to a group of
interaction. Several species
of salmon are anadromous,
vertebrates that made the transition from
30-SECOND TEXT
sometimes migrating huge water to land c. 390–360 million years ago. Peter Capainolo
distances from sea to fresh Actinopterygii are by far the most numerous,
water in order to spawn. comprising around 99 per cent of all fish
Deep-sea angler fish
possess a glowing
species. All these animals exchange oxygen
bioluminescent ‘lure’ and carbon dioxide gases using gills, and many
on their heads to attract possess a swim bladder, which is important in Fish are finned,
prey; the glow is produced
maintaining buoyancy in water. cold-blooded animals
by photobacteria.
that live entirely in salt
or fresh water and
58 g The Vertebrates breathe through gills.
 AMPHIBIANS
the 30-second zoology
Some 370 million years ago, four-
limbed fish began to make short forays on to
the land, giving rise to the first amphibians,
3-SECOND DISSECTION cold-blooded animals able to breathe both in RELATED TOPIC
Amphibians evolved from and out of water. Eventually their descendants See also
fish that could crawl as well FISH
became quasi-terrestrial, feeding on land but
as swim, giving rise to the page 58
first terrestrial creatures
returning to water to lay eggs. These eggs were
with four limbs – the non-amniotic, like those of fish – lacking a hard
precursors of reptiles. shell and producing aquatic larvae that gradually 3-SECOND BIOGRAPHIES
MARÍA CRISTINA ARDILA-
morphed into the adult form – and modern ROBAYO
3-MINUTE SYNTHESIS
amphibians still retain the physical characteristics 1947–2017
Colombian herpetologist
Amphibians are sensitive and reproductive strategies of their ancestors. who described 28 new species
to changes in the Today herpetologists recognize some 7,000 of amphibians from Colombia
and has four species named
environment. Since they species of amphibians, most of which are frogs, after her
breathe through their skin
they absorb small particles and there is great diversity in size, colour and DAVID KIZIRIAN
of possibly harmful survival strategies within the three amphibian 1960–
American herpetologist who
substances, and ecologists groups: frogs, salamanders (including newts) and has discovered and described
have observed that subtle many new species of
caecilians. All amphibians (albeit toads to a lesser amphibians and reptiles
changes in the environment
are manifested by a extent) possess glands in their skin which secrete
decrease in frog and other a smooth, slimy layer of mucus that keeps the
amphibian populations. skin from drying out. Most have lungs but also 30-SECOND TEXT
Occasionally poisons or Peter Capainolo
infectious agents cause
absorb oxygen through their skin, while some
serious mutations in frogs, aquatic species, and the larval stages of all,
including deformities and use gills for gaseous exchange. Many adult
missing or extra limbs. amphibians feed on insect life, but some of the
These phenomena have Most amphibians live
led biologists to consider larger toads and salamanders will catch shrimp, both in water and on
these animals to be crabs and even mice and birds. The least familiar land, but during their
bioindicator species. group are the limbless, snake-like caecilians, egg and larval stages
which are reclusive animals that live in soil in they are wholly aquatic
tropical regions. before becoming
terrestrial adults that
60 g The Vertebrates breathe with lungs.
 REPTILES
the 30-second zoology
Herpetologists recognize
approximately 10,000 species of reptiles, the
vertebrate class that includes lizards, snakes,
3-SECOND DISSECTION turtles, tortoises, crocodiles, alligators and RELATED TOPICS
Reptiles are cold-blooded, tuatara. Reptiles evolved about 310 million years See also
scaly-skinned vertebrates PHYLOGENETICS & DIVERSITY
ago and were able to flourish on land because
that move by crawling or page 22
wriggling and that lay
of several important physical adaptations that
AMPHIBIANS
soft-shelled eggs on land. their amphibian antecedents lacked. Although page 60
still cold blooded, reptiles developed functional
lungs and skin with a leathery or scaly surface.
3-MINUTE SYNTHESIS 3-SECOND BIOGRAPHIES
Several reptile subgroups
Some extinct forms, such as ichthyosaurs and
WILLIAM DOUGLAS BURDEN
appear little changed from plesiosaurs, returned to the oceans and 1898–1978
their distant ancestors, and developed remarkably fish-like bodies, and American naturalist and
filmmaker who shot the first
they display specialisms several species of terrestrial dinosaurs grew to footage of Komodo dragons
that have ensured their and collected the first
survival. Crocodiles have
immense size, possibly influenced by diet, specimens
adaptive metabolisms that climate and other factors. Reptiles were the first
LESLIE JANE RISSLER
enable them to go without group of tetrapods to lay amniotic eggs with an 1969–
food for months. Snakes American herpetologist and
external protective shell, freeing these animals writer who focuses on outreach
hunt by flicking their
tongues to detect particles from the need to lay eggs in water. This led to work with the general public
about evolution
shed by prey animals, reptiles radiating into all major ecological niches
which are then dispatched and further evolving into myriad diverse species.
by constriction or a
venomous bite and
Like other vertebrate groups the majority of 30-SECOND TEXT
Peter Capainolo
swallowed whole. The reptile species are found in tropical and
huge Komodo dragon of subtropical regions; those occupying colder
Indonesia has venom environments will spend much of the winter
glands in its jaws to kill Important evolutionary
prey as large as pigs and
months in a torpid state under leaves and mud. developments that are
small deer. Reptiles in this state have very low heart and features of reptiles,
breathing rates, an evolutionary strategy that notably an egg with a
conserves energy for breeding activities during watery environment
the warm spring and summer months. housed in a shell, paved
the way for a fully
62 g The Vertebrates terrestrial existence.
 BIRDS
the 30-second zoology
The vertebrate class Aves reveals
some of the greatest diversity of any class.
Approximately 10,000 species are living today,
3-SECOND DISSECTION ranging in size from the 2.1-metre (almost 7-foot) RELATED TOPICS
With the ability to fly, birds omnivorous ostrich to the 6-centimetre (2½-inch) See also
rapidly radiated throughout PHYLOGENETICS & DIVERSITY
nectar-feeding bee hummingbird. Birds evolved
the world, monopolizing page 22
food sources and breeding
during the Jurassic period (201–145 million years
ISLAND ODDITIES
ranges to become an ago), close relatives of maniraptoran dinosaurs page 26
enormously successful such as the velociraptor. Modern birds are warm
class of vertebrates.
blooded, have feathers that grow out of the
skin, and lay hard-shelled amniotic eggs. They 3-SECOND BIOGRAPHIES
JOHN GOULD
3-MINUTE SYNTHESIS occupy all ecological niches. Most species can fly, 1804–81
The remarkable variation and physical adaptations that allow life on the British naturalist, ornithologist
among birds makes them and taxidermist who studied
wing include the absence of teeth and urinary Darwin’s finches
favourite subjects for
scientific study. There are bladder, a reduced, fused skeleton and hollow ELLIOTT COUES
birds that can dive and bones. Most are also sedentary and reside in 1842–99
American physician and
swim, ones that burrow but the tropics, but some that breed in northern ornithologist, known for major
no longer fly and a few, scientific writings on birds
latitudes make arduous migrations south every
such as the swift and the
albatross, that spend autumn to overwinter in warmer climes. Many MARGARET MORSE NICE
1883–1974
almost their entire lives species possess high levels of intelligence, using Revered American amateur
on the wing. One of the song, display and mimicry to attract a mate, ornithologist who made
strangest birds is the seminal contributions to
flightless kiwi, which is
building intricate nests and navigating over land the field

endemic to New Zealand. and sea using Earth’s magnetic field. The beaks
It is very mammal-like; its and scale-covered legs and toes of birds are
feathers resemble hair, and 30-SECOND TEXT
adapted to food preference, habitat and Peter Capainolo
it possesses a keen sense
of smell, a trait absent in locomotion: meat-eating raptors have sharp
most birds. curved bills for tearing flesh and toes tipped with Birds have adapted to
sharp talons for gripping prey; seed eaters have most ecological niches
short, strong conical beaks; woodpeckers use and their ability to fly,
their chisel-like bills and long sticky tongues for walk, climb, run and
extracting insects while clinging to trees. swim sets them apart
64 g The Vertebrates from other classes.
 MAMMALS
the 30-second zoology
Ancient reptiles known as
synapsids are thought to have given rise to the
vertebrate lineage that evolved into modern
3-SECOND DISSECTION mammals. All mammals are warm blooded and RELATED TOPICS
Reproductive strategies in have hair or fur; all are tetrapods and most are See also
the mammalian subclasses NATURAL SELECTION
placental, meaning their young develop in the
reveal an evolutionary page 18
path: egg-laying in
uterus before birth. Humans are placental
PHYLOGENETICS & DIVERSITY
monotremes is primitive; mammals, as are whales, illustrating how diverse page 22
semi-foetal births in mammals are but also how closely related,
marsupials intermediate; and
based on a similar reproductive strategy. Once
placental development most
born, infant mammals remain highly dependent 3-SECOND BIOGRAPHIES
advanced, but all mammalian JOSEPH GRINNELL
mothers produce milk. on their mothers and need to be fed on their 1877–1939
mother’s milk. Marsupials, the group of The first director of the
Museum of Vertebrate
mammals that includes kangaroos, give birth to Zoology, University of
3-MINUTE SYNTHESIS California, Berkeley, who
The largest living mammal
undeveloped foetus-like young that make their conducted major surveys of
way into the mother’s abdominal pouch. There mammal populations
is the blue whale and
among the tiniest are they feed from milk glands until they are old DANIELLE ‘HOPI’ ELIZABETH
smaller-than-thumb-sized HOEKSTRA
enough to emerge and fend for themselves. 1972–
species of shrew. Whales
and shrews may be hugely A third group of mammals, the monotremes American evolutionary
biologist who studies the
divergent in appearance – which includes the platypus and spiny anteater genetic basis of adaptation
and behaviour, but under of Australia and New Guinea – are the only using wild rodent populations
the skin are similarities.
Even marine-dwelling
mammals to be born from eggs laid outside the
mammals feed their young mother’s body. Milk is provided to their young 30-SECOND TEXT
milk: a blue whale calf daily through pores in the skin, as monotreme milk Peter Capainolo
drinks about 350 litres glands are relatively small compared with other
(77 gallons) of milk in its
first few months. Milk and
mammals, and mothers have no nipples. It is
parental care has allowed this provision of milk and the associated high
mammals to adapt to some level of parental care that truly defines what
of the most extreme
it is to be a mammal. Marsupials, mammals
habitats on Earth.
and monotremes have
more in common than
66 g The Vertebrates meets the eye.
 g
PHYSIOLOGY
 PHYSIOLOGY
GLOSSARY

abiogenesis The origin of life from haemotoxins Toxins that damage red blood
non-living matter, the transition from cells; can often alter how blood clots and
chemical processes to biological ones. cause organ damage and eventual failure. This
can be either through the toxin preventing of
cones and rods Photoreceptor cells in the clotting, leading to internal bleeding, or by
eye. See opsin. causing blood cells to clump together at much
higher rates than normal, blocking blood
cytotoxins Substances having a toxic vessels.
effect on cells, leading to cell and organ
death, a condition known as necrosis. imaginal discs A patch of tissues, that form
in a larval insect, which develop into adult
ectoderm The outer layer of tissue in an structures, such as wings, antennae and legs,
embryo that develops into the skin and at metamorphosis.
nervous system.
mesoderm The middle layer of the tissues in
endoderm The innermost layer of tissue in an embryo, develops into bone, cartilage and
an early embryo which will eventually form muscle.
the gut.
neurotoxins Poisons that act on the nervous
gastrulation The movement of tissue in a system, disrupting the normal chemical
single (tissue) layered blastula stage signals sent between nerve cells or along the
embryo to form a multi (tissue) layered neuron itself.
gastrula.
organizer A region of a developing embryo
germ layers The ecto-, meso- and that secretes signalling molecules that direct
endoderm tissues that form specific tissues and ‘organize’ development.
and organs throughout development.

70 g Physiology
organogenesis The formation of organs,
from defined tissues from specific germ
layers.

opsin A light-sensitive protein found in

the photoreceptor cells (cones and rods)
of the eye. Different opsins are sensitive
to different wavelengths (energies) of light
and combinations of different opsins allow
us to see different colours.

polarization In the optical sense, the

direction in which a wave of light oscillates
while moving. The term also defines the
spatial biological specificities in a cell
during development, providing the
tail–head axis, for example (see page 16).

resorption Refers to the reabsorption

of larval tissue (such as the tail and gills),
as the juvenile develops.

Glossary g 71
 3 August 1915 1942 1958
Born in Southampton, Asked to contribute to Awarded the Daniel
New York, USA developing a bat bomb by Giraud Elliot Medal by the
the US National Defense US National Academy of
Research Committee Sciences for meritorious
1934–42 work in zoology
Studies at Harvard
University, 1946–53
Massachusetts, USA Teaches zoology at 1965
Cornell University, Ithaca, Joins Rockefeller
New York, USA University, New York City,
1941 USA
Developed the concept of
echolocation with Robert 1952
Galambos Elected a fellow of the 1976
American Academy of Publishes The Question
Arts and Sciences of Animal Awareness,
arguing that animals are
conscious beings
1953–65
Returns to Harvard
University as professor of 1986
zoology Retires from Rockefeller
University

7 November 2003
Dies at the age of 88
in Lexington,
Massachusetts, USA

72 g Physiology
DONALD GRIFFIN

Few scientists can claim to have attached to bats that would be dropped by
changed the way that people view animals, but aeroplanes at night over Japanese cities.
Griffin did it twice: first, when his studies Seeking shelter during the day, the bats would
revealed the way some animals navigate by roost in buildings, and the explosives would
using echolocation and, second, with his work detonate and set off fires. Griffin helped
in the field of cognitive ethology. develop the proposal and even collected
Donald Redfield Griffin was born in Mexican free-tailed bats to test their load-
Southampton, New York, in 1915. As a youth he bearing capacity. Bat bombs were never used in
was a keen naturalist, and he first worked with combat, however, and he later questioned the
bats while still in high school, researching the ethics of using animals in such a way.
migration patterns, homing instincts and Griffin pioneered cognitive ethology, a field
lifespan of brown bats, Myotis lucifugus. concerned with the influence of conscious
His academic career started with research in awareness and intention in animal behaviour.
comparative physiology. While an By studying animals in natural habitats rather
undergraduate at Harvard he worked with than in unnatural environments with artificial
fellow student Robert Galambos to begin to stimuli his research led him to believe that
unravel the secrets of how bats navigated in the animals were capable of thinking, that they
dark, using a small dark room in which obstacles were conscious and not automata. Publishing
could be placed. Realizing that bats could use his ideas in his 1976 book The Question of
reflected sound to identify and detect objects, Animal Awareness, this was – and remains in
Griffin described how this worked and gave this some quarters – highly controversial and led to
previously unknown way of ‘seeing’ the world a accusations of anthropomorphism. However,
name: echolocation. It was a contentious idea in his seminal work has shaped the discipline of
scientific circles, but the discovery was a major zoology, and scientists have developed the field
breakthrough – importantly, it also informed further by exploring how animals can form
the development of radar and sonar. concepts and anticipate the actions of others.
One surprising development of his work with Griffin was a prolific writer – as well as a
bats came in 1942 when he was asked by the number of books he published over 100 papers
US National Defense Research Committee to between 1938 and 2001. After his retirement in
evaluate an idea for a ‘bat bomb’. This called 1986 he lived in Lexington, Massachusetts,
for tiny time-delayed explosive devices to be where he died in 2003.

Rebecca Thomas

Donald Griffin g 73
 DEVELOPMENT
the 30-second zoology
Development takes an egg and
sperm from one generation and turns it into a
functioning individual in the next. A single cell
3-SECOND DISSECTION becomes trillions in humans – or exactly 959 RELATED TOPICS
Development increases in the body of Caenorhabditis elegans, a See also
cell numbers, differentiates GENES
nematode worm. Despite these vast differences
cells into tissues and turns page 16
these into organs, but it
in numbers, in both worms and people the same
METAMORPHOSIS
doesn’t stop there; after processes occur. The first is embryogenesis. page 76
hatching or birth, further Following fertilization the cell divides, increasing
development turns
the number of cells and allowing differentiation.
juveniles into adults.
More than one cell means that they can do 3-SECOND BIOGRAPHIES
J. B. S. HALDANE
different jobs. A cell’s relative position in the 1892–1964
3-MINUTE SYNTHESIS embryo makes it different from others. Cells on British-Indian evolutionary
geneticist, biometrician,
Development can be seen the surface are called ectoderm (outside layer) physiologist and
as an analogy for the mathematician; introduced the
process of evolution. The
and the layer on the inside endoderm. Cell Oparin–Haldane hypothesis on
movement at gastrulation forms the gut and abiogenesis and the primordial-
idea that evolution can soup theory
mould simple single-celled puts other cells between the outer and inner
organisms and make HILDE MANGOLD
layers, making mesoderm. From these layers 1898–1924
complex multicellular
ones is often difficult to different organs can form, a process called German embryologist whose
exquisite work on the
comprehend: after all, organogenesis. Ectoderm will form skin and the development of amphibians
what are the chances? showed how the vertebrate
nervous system, while endoderm forms gut body plan is organized
However, as evolutionary
biologist J. B. S. Haldane
tissue. The mesoderm forms muscles and, in
said, ‘you did it yourself in vertebrates, the bony skeleton. Development is
30-SECOND TEXT
9 months’: from a single the result of an interplay between genes Neil Gostling
fertilized egg, you are now specifying a body axis and those identifying
sitting reading these
words. Evolution and
specific regions within the embryo and the
development writ large. environment that the cells are in. Specific This beautiful process
organizers within embryos secrete proteins to takes a single fertilized
give exact positional identity, meaning that the egg cell and turns it into
right body parts form in the right places. a multicellular organism
with the ability to repeat
74 g Physiology the whole process again.
 METAMORPHOSIS
the 30-second zoology
Metamorphosis is the process
of change that for some groups of organisms
results in larvae transforming into very different
3-SECOND DISSECTION adult forms. This has the ecological benefit of RELATED TOPICS
Metamorphosis occurs reducing competition between adults and their See also
when significant physical GENES
offspring for food and habitat resources while
changes in animal body page 16
form occur between
also allowing for differences in dispersal. The
DEVELOPMENT
life-history stages, such most recognized forms of metamorphosis are page 74
as between the larval and seen in amphibians and insects, but they take
adult stages of butterflies.
radically different routes to adulthood. For
example, in frogs it is really only an elaboration 3-SECOND BIOGRAPHY
MARIA SIBYLLA MERIAN
3-MINUTE SYNTHESIS of the existing body plan: an outgrowth of 1647–1717
In almost all organisms legs and the development of lungs, with the German naturalist whose
detailed observations of the
that partition life history resorption of gills and the tail, for the transition life cycles of insects were some
into a larval and adult of the first to describe
stage, the ability to
from water to land. In flies and other insects, metamorphosis accurately
reproduce is held back the process is much more extreme. While the
until after metamorphosis. fly’s head-to-tail axis remains, just about every
However, one amphibian 30-SECOND TEXT
part of the larval body is broken down, and the
has found a halfway house Neil Gostling
between juvenile and adult adult structures develop from non-functional
lifestyles. The axolotl, regions of the larval body. These areas, called
which inhabits a few miles imaginal discs, develop at metamorphosis into
of river near Mexico City,
is a salamander that retains
legs, wings and all of the appendages and
the gills of the juvenile, anatomical structures necessary for the adult
so cannot survive out to transition from a life in the soil, exploiting
of water, but is sexually the niche for food and growth, to a world on the
mature in its juvenile body.
wing, looking for a mate. It’s at metamorphosis
where individuals become sexually mature and Spiders, invertebrates,
can reproduce. butterflies and other
insects undergo
metamorphosis, as
do some tetrapods,
76 g Physiology including amphibians.
 BREATHING
the 30-second zoology
The ability to take air into the
body and then exchange oxygen for carbon
dioxide is key to animal life itself. Every cell
3-SECOND DISSECTION needs oxygen for respiration, and breathing RELATED TOPIC
Breathing is key to aerobic helps get it where it’s needed. There are four See also
respiration; in the presence DEVELOPMENT
primary ways of getting oxygen into the body.
of oxygen glucose breaks page 74
down and produces carbon
The simplest sees oxygen diffusing across the
dioxide, water and, surface of the body to the cells beneath, but
critically, the energy that this is suitable only for small simple animals in 3-SECOND BIOGRAPHY
powers life. WILLIAM HARVEY
moist environments, and larger species require 1578–1657
specialized organs. Gills allow animals in aquatic English physiologist who was
the first to provide anatomical
3-MINUTE SYNTHESIS environments to exchange gases. Gills are evidence for the crucial links
between the respiratory and
While there are four main membranes, often only one cell thick, that allow circulatory systems
ways of getting oxygen to a rapid exchange of gases, bringing oxygen into
where it’s needed, some
species do things a little
contact with the circulatory system. For terrestrial
species things are more complicated. Larger 30-SECOND TEXT
differently. Fitzroy River
Mark Fellowes
turtles in Australia have invertebrates, such as insects, have tracheal
lungs but gain around
systems. These are networks of air tubes which,
70 per cent of their oxygen
requirement through cloacal as there is no circulatory system, ramify through
respiration (colloquially the insect’s body bringing oxygen to the cells
known as ‘breathing where needed. This contrasts with the complexity
through their bums’,
although, strictly speaking,
of lungs found in terrestrial vertebrates, such
the cloaca is not the same as humans. Air is drawn through a series of
There are several ways
as the anus), where progressively smaller and more branched tubes,
specialized cells act like of getting oxygen to
starting with the trachea, dividing into bronchi
alveoli. This allows the where it’s needed,
turtle to remain under
which, in turn, divide into bronchioles and then but what works
water for several days. into tiny sacs, the alveoli, where gas exchange best is constrained
occurs and the circulatory system can carry by physiological
oxygen to individual cells. limitations. Frog eggs
rely on diffusion,
tadpoles on gills
78 g Physiology and adults on lungs.
 VISION
the 30-second zoology
The ability to sense light
gives animals access to a high-resolution
instantaneous information source with which
3-SECOND DISSECTION to assess the world around them. All eyes have RELATED TOPICS
Eyes allow animals to see, opsins, light-sensitive molecules that absorb See also
but not all species see in GENES
light of particular energy levels, known by their
the same way: humans page 16
have three colour channels,
wavelength. These opsins are packaged into
PHYLOGENETICS & DIVERSITY
dogs have two, birds have specialized cells (cones and rods) in the retina. page 22
four and mantis shrimp We perceive these different wavelengths as
have a dozen!
different colours, although electromagnetic
radiation (light) has no colour in its own right. 3-SECOND BIOGRAPHY
HASAN IBN AL-HAYTHAM
3-MINUTE SYNTHESIS Instead, colour is created by the brain when it c. 965–c. 1040
Eyes have evolved compares the activity of different light-sensitive Scientist born in Basra
(present-day Iraq) who
independently many cells: humans have three types of colour-sensitive investigated how light is
different times to varying received by the eyes and
levels of complexity,
cell (cones) while other life forms can have many interpreted by the brain
from simple patches of more, opening up further ways of seeing their
light-sensitive cells found environments. The colours that animals can
in flatworms to the 30-SECOND TEXT
detect depends on which combination of James Barnett
complex compound eyes of
insects and the camera-like wavelengths they are sensitive to, and many
eyes of vertebrates and species can see further into the ultraviolet and/or
squid. Some animals infrared than humans. But animals are not just
cannot see colour, and
dolphins, whales and seals
limited to seeing colour: light can be described
may see only black, white both by how much energy it has and by the
and shades of grey; direction in which the wave propagates, its
others, however, see polarization. This is what polarized sunglasses
colours beyond our
comprehension. Many
allow humans to see, but many animals (including
birds are even more bright crabs and cuttlefish) have this feature built in, Light is all around us,
and beautiful than we can giving them the ability to distinguish things but we humans can only
ever appreciate.
that match the background in colour. see a small amount of
the spectrum, and to
other species the world
80 g Physiology can look quite different.
 VENOMS & POISONS
the 30-second zoology
The age-old confusion over
terminology: is that snake poisonous or
venomous? Both exist, and both produce toxic
3-SECOND DISSECTION chemicals that can cause illness or even death, RELATED TOPICS
Both poisons and venoms but the distinction lies in whether the trouble See also
are toxic chemicals, but JELLYFISH, CORALS,
results from you biting it or it biting you.
poisons must be ingested ANEMONES & MORE
(you bite it), while venoms
Venomous species inject their toxins directly page 36
are injected (it bites you). through modified teeth, stings or spines that AMPHIBIANS
can be used both for capturing prey and in page 60
self-defence; poisonous species excrete or store REPTILES
3-MINUTE SYNTHESIS
toxins in or on their bodies, largely to defend page 62
Not all poisonous species
generate their own toxins; themselves from predators or parasites. A huge PREDATION
some sequester toxins variety of different chemical toxins is used as page 122
from the plants and both venoms and poisons by different species
animals they eat. Many
of the brightest-coloured
from jellyfish to frogs to trees. Venoms fall
3-SECOND BIOGRAPHY
butterflies and moths gain broadly into two categories: those that disrupt VITAL BRAZIL
their chemical defences the signals between nerve cells (neurotoxins) 1865–1950
from the plants they Brazilian scientist who
and those that break down cells (cytotoxins and developed some of the first
consume as caterpillars. snake anti-venoms; his work
For example, monarch haemotoxins). Neurotoxins stop nerve signals massively reduced the death
from reaching muscles, leading to paralysis of rate from snakebites
butterflies gain their toxins
from milkweed plants and vital bodily functions such as breathing and the
cinnabar moths from
heart beating. Cytotoxins and haemotoxins 30-SECOND TEXT
ragwort. The colours that
make butterflies beautiful break down bodily tissues, disrupting cells and James Barnett
to us represent a warning preventing blood from clotting. However, as
signal to potential prey evolve toxicity, predators evolve resistance
predators that says, ‘Eat
me, and you’ll regret it.’
in an arms race that can result in enormous Toxins manufactured
concentrations of toxins in some species. For by insects, reptiles,
example, the rough-skinned newt found in amphibians, fish,
California is so toxic that it could kill several arthropods and even
adult humans but is routinely eaten by garter birds can act as
snakes immune to its powerful poison. deterrent, defence
82 g Physiology or deadly weapon.
 FLIGHT
the 30-second zoology
Many organisms use air currents
to disperse, and some use specialized structures
to glide, but true powered flight is special
3-SECOND DISSECTION because it allows animals to choose where RELATED TOPICS
Flight, the means to to go. Powered flight first evolved in insects See also
self-propel through NATURAL SELECTION
about 400 million years ago, and much like
the skies, proved page 18
advantageous to those
the metamorphosis from earthbound larvae to
PHYLOGENETICS & DIVERSITY
organisms that evolved this flying adults seen today, the transition to the air page 22
ability because it opened allowed insects to exploit new niches – and it
up new niches and BIRDS
might also explain the incredible diversity of the page 64
opportunities.
group. Flight has also evolved independently
METAMORPHOSIS
from flightless ancestors in three other page 76
3-MINUTE SYNTHESIS vertebrate groups – the (now extinct)
Charles Darwin predicted pterosaurs, birds and bats – each of which
that fossils linking the major 3-SECOND BIOGRAPHY
groups of living animals
has modified its forelimb to make a wing. In
THOMAS HENRY HUXLEY
would be found. In the pterosaurs the wing was a thin skin membrane 1825–95
1860s a fossil feather was supported by the arm and an extremely Known as ‘Darwin’s Bulldog’
for his passionate defence of
discovered in a quarry in
elongated little finger – indeed, Pterodactylus evolutionary theory, Huxley
Bavaria, southern Germany, was one of the greatest
followed by a body fossil means wing finger. Bird wings incorporate the anatomists of his day and one
of the first to suggest a link
covered in feathers. The humerus, radius and ulna and hand, together between birds and dinosaurs
specimen also had a long forming an aerofoil with feathers. Bat wings
bony tail, a jaw with teeth
and clawed fingers. It was
are formed from the whole hand (the order to
30-SECOND TEXT
described as a bird (it had which bats belong is Chiroptera, meaning hand Neil Gostling
feathers), but it clearly had wing) the elongated fingers of which have a skin
reptilian, dinosaur features. membrane in between. It is hard to say how
Archaeopteryx was Flying animals comprise
Darwin’s predicted link and
flight evolved in pterosaurs or bats, because the largest living group
is described as the first bird. fossil records contain no intermediate forms. (insects) and the largest
Birds, however, have a rich fossil record that group of tetrapod
shows the transition from small feathered vertebrates (birds) on
dinosaurs to modern birds. Earth. The bat is the
only mammal capable
84 g Physiology of powered flight.
 g
BEHAVIOUR
 BEHAVIOUR
GLOSSARY

binomial nomenclature The classification monogamy Mating system where each male
system whereby organisms are named and each female mates with only
using a two-word identifier, the first being one partner.
genus and the second the species.
monophyletic group Organisms that included
bombykol The first pheromone to be the last common ancestor and all of its
identified chemically is used by female silk descendants, living and extinct.
moths to attract males.
operant conditioning A learning process by
eusociality Complex social systems where which the expression of a behaviour (the action)
multiple generations of adults overlap is changed by reinforcement or punishment.
within a single society, and where the These can be positive or negative. Positive
majority of individuals do not reproduce to reinforcement, for example, may involve the
support the reproduction of a queen, as use of reward, while negative reinforcement
seen in many ants, bees and wasps. may be associated with avoiding a negative
stimulus, such as a loud noise.
hermaphrodite An organism that
possesses both male and female pheromone A chemical released into the
reproductive organs at some stage in its environment by an animal that acts on
life span. Many invertebrate groups, such the physiology or behaviour of another
as snails, slugs and worms, do not have individual.
separate sexes and a number of fish
families and some reptile species are also phylum (pl. phyla) The first taxonomic
hermaphroditic. division of animals below the kingdom (see
taxonomy).
kin selection Where workers are related
to the offspring and hence increase their polyandry Mating system in which females
evolutionary fitness by helping to rear mate with multiple males.
siblings.

88 g Behaviour
polygamy Mating system in which males
mate with multiple females.

polygynandry Mating system where both

males and females mate with multiple
partners.

reciprocal altruism A behavioural trait

where an individual acts selflessly to help
another at one time but will benefit when
the roles are reversed in the future.

sexual dimorphism Where males and

females of the same species look or behave
differently.

spermatozoa The male sex cells (that is,

sperm), the plural of spermatozoon, the
mobile single cell that carries the father’s
DNA to fertilize the egg.

taxonomy The traditional classification

system for naming and organizing the
animal (and plant) kingdom into groups
that share similar qualities. The seven ranks
are: kingdom, phylum, class, order, family,
genera and species. By contrast,
phylogenetic or cladistic nomenclature ties
names to a clade, the name for a collection
of organisms that group together through
the possession of shared characteristics
inherited from a common ancestor.

Glossary g 89
 10 June 1929 1955 1979
Born in Birmingham, Awarded a PhD in biology Wins the Pulitzer Prize
Alabama, USA from Harvard University, for general non-fiction
Massachusetts, USA for On Human Nature,
which deals with the role
1949/1950 of biology in the
Graduates with a BS then 1956–76 evolution of human
MS in biology from the Teaches at Harvard, culture
University of Alabama becoming a full professor
in 1964
1990
Awarded the Crafoord
1973–97 Prize by the Royal
Becomes curator in Swedish Academy of
entomology at the Sciences
Museum of Comparative
Zoology, Harvard
1991
Wins a second Pulitzer
1976 for general non-fiction
Awarded the US National for The Ants, co-authored
Medal of Science with Bert Hölldobler

1997–
Becomes honorary
curator in entomology
at the Museum of
Comparative Zoology,
Harvard

90 g Behaviour
E. O. WILSON

Edward Osborne Wilson was island’s biodiversity is related to two factors,

born in 1929 in Birmingham, Alabama, USA. size and isolation, and how this leads to small
He was precociously interested in science, but isolated islands having fewer species than larger
a fishing accident when he was seven caused islands near other islands. This theory was
him to lose the vision in one eye, resulting in tested by dynamiting islands in the Florida Keys
him becoming focused on ‘little things’, as he to change their size and then removing all insect
described them, in particular butterflies and life with insecticides. By recording the changes
ants. By the time he was 18 he was already an in biodiversity over time Wilson was able to
expert entomologist, reporting the first colony show that his theories were essentially correct,
of invasive fire ants in the USA while still in high and this insight has become the keystone of
school. Wilson attended the University of modern conservation biology.
Alabama before completing his PhD at Harvard In the face of the enormous biodiversity losses
in 1955. He remained at Harvard, researching across the globe, in his later career he has
ant taxonomy and evolution and later becoming emphasized the importance of conservation,
curator of entomology at Harvard’s Museum of introducing the term ‘biophilia’ to describe what
Comparative Zoology. he argues is humankind’s innate, genetically
Wilson is perhaps the world’s most famous determined need to connect with nature. This
ant expert, particularly in regard to his research has been significant in shaping how conservation
on how ants use pheromones to communicate. biology in the Anthropocene is approached.
It was the self-sacrificing nature of ants that Wilson’s wider influence is considerable.
helped influence his contribution to a new He has brought to the public’s attention
scientific discipline, sociobiology, which studies fundamental questions about what makes us
animal behaviour from a social perspective. human, why societies work the way they do and
Controversially, Wilson has also applied these how we must strive to save what remains of the
perspectives to human behaviour, arguing that it natural world for future generations. He has
is as much genetically as culturally determined, won numerous prizes, including the Pulitzer
fuelling debates about the relative levels of Prize (twice) and the Royal Swedish Academy’s
nature and nurture in human behaviour. Crafoord Prize (which recognizes sciences not
His most notable contribution to ecology was covered by the Nobel categories) and was
in his involvement in developing the field of named as one of the 25 most influential
island biogeography, which shows that an Americans by Time magazine in 1995.

Mark Fellowes

E. O. Wilson g 91
 LEARNING
the 30-second zoology
Animals are able to learn from
experience, altering behaviours in response to
stimuli. At a simple level, this happens through
3-SECOND DISSECTION habituation (a reduction in response) or RELATED TOPIC
Learning is an ability to sensitization (an increase in response) to a See also
modify behaviour and then NATURAL SELECTION
stimulus. This is non-associative learning, where
repeat that behaviour in page 18
the future in a manner that
the presence of a single stimulus is directly
may benefit an organism’s linked to a change in behaviour – one example
survival. being urban pigeons learning that humans 3-SECOND BIOGRAPHIES
IVAN PAVLOV
present little threat. More complex is associative 1849–1936
3-MINUTE SYNTHESIS
learning, where two or more stimuli become Russian/Soviet physiologist
best known for his research
Learning can lead to associated by the learner. This can be in the on classical conditioning,
particularly his work with dogs;
cultural differences. form of classical conditioning, where the animal he was awarded the Nobel
Chimpanzees use branches, learns to associate a stimulus with a pre-existing Prize for Physiology or
twigs and leaves as tools to Medicine in 1904
help find food. In Uganda,
behaviour – as seen with Ivan Pavlov’s dogs
JANE GOODALL
chimpanzees in Kibale use salivating at the ringing of a bell because they 1934–
sticks to get honey, but had learned to associate the sound with the British primatologist who has
those in Budongo soak up shown how extensive tool
presence of food – or it can be in the form of use is among chimpanzee
honey with chewed leaves. populations
These cultural differences operant conditioning, where reward or
arose because of chance punishment changes behaviour. This is typical of
differences in insight dog training, where rewards reinforce positive 30-SECOND TEXT
learning, followed by
reinforcement in the
behaviours in response to commands. But other Neil Gostling

population from forms of learning are much more complicated.

Bears learn that where
observational learning as Some species can learn from observing others
skills are passed from one there are bees there is
and copying novel behaviours. Others learn
individual to another. Some honey but how could
animals are not so different through insight, where experience informs bees have learned to
from humans after all. reasoning, a form of learning only found in more construct honeycomb
intelligent species such as primates and crows. based on a hexagon (the
This leads to intricate, adaptable behaviours, most efficient shape in
as epitomized by our own species. terms of strength and
materials), which
92 g Behaviour appears instinctual?
 COMMUNICATION
the 30-second zoology
Animals communicate. Their
signals convey information that can influence
the receiver, thus allowing the complex,
3-SECOND DISSECTION complicated richness of animal behaviour to RELATED TOPIC
Animals communicate emerge. Signals may be exchanged through any See also
through sights, sounds, GROUP LIVING
of an animal’s senses. While humans largely
smells, touch and page 100
behaviour to convey
communicate through sound and gesture, other
intent, assess mating species signal each other in ways difficult for
potential, warn each us to imagine, such as the electrical pulses of 3-SECOND BIOGRAPHIES
other of danger and to ADOLF BUTENANDT
knifefish or the chemical cues that make up 1903–95
coordinate group activity.
pheromones. Pheromones were first isolated German Nobel Prize-winning
biochemist who identified the
60 years ago when the chemical bombykol – pheromone bombykol in 1959
3-MINUTE SYNTHESIS which female silk moths use to attract males ALEX THE AFRICAN GREY
We humans communicate from great distances – was first described. 1976–2007
all the time by using A parrot, raised by animal
sounds (speech), visual
While widespread, particularly in insects, psychologist Dr Irene
cues (body language) and pheromone use by species such as humans Pepperberg, who developed
a vocabulary of more than
even chemicals (smell). remains highly controversial. Communication 100 words for different objects
While communication in and actions
between members of the same species allows
the animal kingdom can
take many different – and, animals to convey and assess one another’s
to us, sometimes surprising intentions and qualities as a mate or rival as well 30-SECOND TEXT
– forms, only a few species as allowing groups to coordinate their collective James Barnett
have developed specific
sounds that have been
behaviour. This may range from relatively simple
suggested might function olfactory markers left at the edge of a territory
in a similar manner to to elaborate multisensory displays and the
words: bottlenose dolphins complex coordination of group foraging and
produce unique signature
whistles that identify
defence. Communication between species is
individuals, and several less complex and is usually designed to convey Communication of one
monkeys and birds use threats, but it can result in shared benefits, form or another is the
specific alarm calls for
such as when honeyguides (an African bird) lead basis of all interactions
specific predators.
honey badgers (and also humans) to beehives. between individuals,
groups or species.
94 g Behaviour
 MANAGING
CONFLICT
the 30-second zoology
Animals need access to a few
essential things to be successful: territory, food,
water and mates. But everyone else out there is
3-SECOND DISSECTION after the same, and when there isn’t enough to RELATED TOPICS
Conflicts over food, mates share things can become dangerous. When See also
and territories arise all the COMMUNICATION
conflict arises there are two options: fight or
time, and, rather than risk page 94
fighting, animals shout,
flee. Fighting creates the risk of being injured
ALTRUISM
posture and bluff their way and can waste time and energy, but fleeing page 98
through while avoiding means giving up precious resources that are
physical fights. GROUP LIVING
unlikely to be found undefended elsewhere. So page 100
perhaps conflict should be managed in a more
3-MINUTE SYNTHESIS nuanced fashion. Many species use behavioural
Chameleons are known displays to pre-empt the outcome of any fight 3-SECOND BIOGRAPHY
DIAN FOSSEY
primarily for their ability to and allow the loser to back down prior to any 1932–85
change colour so enabling
them to blend into the
physical conflict. Mouth gaping, side-by-side American primatologist who
transformed the understanding
background and avoid struts and displays of horns, bellows or of gorilla behaviour and
highlighted how display and
detection by predators, weaponry all allow rivals to size up their communication were used by
but these diminutive gorillas to avoid conflict
opponents and forecast the likely outcome of
reptiles can also be fiercely
territorial, defending their a fight. Conflict is not always as dramatic as a
patch from all intruders. physical confrontation, but its costs will still 30-SECOND TEXT
Fighting can be dangerous, need to be mitigated. Competition for resources James Barnett
so, when confronted,
chameleons may hiss
between individuals of the same species can
loudly, inflate themselves, lead to partitioning of resources and activity
extend exaggerated frills patterns so that each exploits their own niche.
and change colour The same principle extends between species
dramatically from passive
green to fiery red. Only
– for example, competitive herbivores Animals are always in
if all this fails to scare specializing towards particular resources or competition with one
off a rival will they eating leaves on the same plant as other another, for food,
physically fight.
species but at different elevations. space or mates, but
competition does not
always need to result
96 g Behaviour in physical conflict.
 ALTRUISM
the 30-second zoology
The natural world is full of
examples of cooperative animals working
together or seemingly acting selflessly for the
3-SECOND DISSECTION benefit of others: meerkats take turns giving up RELATED TOPIC
Altruism is active and food to keep watch while others feed; vampire See also
selfless behaviour by GROUP LIVING
bats have been known to share food with those
one or more individuals page 100
to benefit another of
who haven’t found enough; and ants will
their kind or an entire sacrifice themselves for the good of the colony.
community. But evolution favours genes that increase 3-SECOND BIOGRAPHY
ROBERT TRIVERS
survival and reproductive success. Giving 1943–
3-MINUTE SYNTHESIS
precious resources to others would, therefore, American evolutionary
biologist and sociobiologist
Reciprocal altruism can be appear to go against natural selection, with any who developed the
mathematical theory of
summed up as the ‘you selfless (altruistic) individuals at risk of being reciprocal altruism in 1971
scratch my back, and I’ll taken advantage of and outcompeted by more
scratch yours’ approach.
By acting altruistically to
selfish individuals who keep resources to
themselves. This apparent paradox is solved by 30-SECOND TEXT
those in need, an individual
James Barnett
with resources to spare can understanding the indirect benefits of altruistic
increase the likelihood of
behaviour: kin selection and reciprocal altruism.
repayment when and if
the roles are reversed. Natural selection works not on the species nor
Of course, there may be even the individual but on the genes within
cheats who will attempt to them, and those genes are shared by close
take advantage of such
acts of selflessness, so it
relatives. By sharing resources with related
always pays to keep track individuals and increasing the chances that they
of which members of the can survive and reproduce, acting altruistically
community are trustworthy can benefit an individual indirectly by increasing
and which aren’t. Natural selection
the overall representation of their genes in the favours genes that
next generation. But you don’t have to be maximize an
related for altruism to persist. In some social individual’s survival
species, being able to remember who’s who and reproduction,
allows mutually beneficial social networks to but being selfish is not
persist, with favours granted and returned. always the best way to
98 g Behaviour get the most benefits.
 GROUP LIVING
the 30-second zoology
What do lions, termites, dolphins
and emperor penguins have in common? They all
spend at least part of their lives in groups. But
3-SECOND DISSECTION why would such different animals all evolve to RELATED TOPICS
Living together can allow live socially? Living together makes animals See also
groups of animals to more conspicuous to predators, allows disease E. O. WILSON
defend themselves better, page 92
raise their young and work
to spread more easily and puts every individual
COMMUNICATION
together to find more food in direct competition for resources. Social living page 94
than they could alone. can, however, offer significant benefits. Where
ALTRUISM
food is scarce, it can allow more efficient page 98

3-MINUTE SYNTHESIS
foraging. Groups of predators may be better
Group living has been able to tackle a wider range of prey, increasing
3-SECOND BIOGRAPHY
taken to extremes by the reward for each individual and allowing
BERT HÖLLDOBLER
eusocial species, such access to large or well-defended prey that 1936–
as ants, bees, termites, Influential German
some shrimps and naked
would otherwise be unavailable. Prey species sociobiologist and
mole-rats (the only benefit from simple safety in numbers: larger entomologist who, along
with E. O. Wilson, won the
mammals that truly live groups have more eyes looking for threats, and, Pulitzer Prize for The Ants,
in this way), showing a book on ant societies
if attacked, a group is better equipped to fight
the highest levels of
cooperation and sociality off predators. Indeed, safety in numbers works
to be found anywhere. not just by decreasing the chance that any 30-SECOND TEXT
Eusocial colonies, individual will be unlucky but, by acting as a James Barnett
sometimes numbering
millions of individuals,
large unpredictable mass, the group can confuse
work together to raise approaching predators, making the task of
offspring, collect food isolating a target more challenging. In eusocial
and build large communal species, huge numbers cooperate on a level not
structures with a clear
division of labour among seen elsewhere in the animal kingdom. In these
groups, or castes, within colonies all individuals are closely related, so
the colony. working together, even if at personal cost,
maximizes the chances of their genes passing Working together
to the next generation. means sharing:
sharing rewards but
100 g Behaviour also sharing costs.
 MATING
the 30-second zoology
Mating combines eggs and
sperm to create the next generation – but there
are many ways of getting there. Species may be
3-SECOND DISSECTION monogamous, with just one sexual partner, either RELATED TOPICS
Mating is the physical one at a time or one for life – although such See also
process by which sperm SEXUAL SELECTION
mating systems are frequently fuzzier than they
and eggs are brought page 104
together, allowing the
might at first appear, with extra-pair matings
SPERM COMPETITION
mixing of parental genes in found in even strictly socially monogamous page 106
a way that creates unique species – or polygamous, with multiple mates at
new individuals. SEX ALLOCATION
once. In some species males mate with multiple page 108
females (polygamy); in others females mate with
3-MINUTE SYNTHESIS multiple males (polyandry); and in others again
Driven by both natural and both sexes mate with multiple partners 3-SECOND BIOGRAPHY
OLD BLUE
sexual selection, mating (polygynandry). The mating system favoured 1970–83
systems can be highly
variable. In hermaphroditic
depends on how reproductive investment differs By 1980 Old Blue was the last
surviving fertile female New
species such as snails, between the sexes and how much parental care Zealand black robin; all black
robins today can trace
which have both male and is required, but males and females may not agree themselves back to this
female sex organs, you may one individual
on what strategy is best. The female is most
see competition to decide
who will produce eggs and often the limiting sex, as the number of eggs
who will produce sperm that she can produce is much lower than the 30-SECOND TEXT
when they mate. Our own number of eggs a male could theoretically James Barnett
system as humans is no
more ‘normal’ than that of
fertilize. There are exceptions, however, and
any other species; it is where males provide particular care or resources
simply the outcome of they may act as the limiting sex. This is seen in
what helped pass on the the red-necked phalarope, a wading bird, where
most genes in our
evolutionary past.
females compete for males who will care for
their young; free from the burden of raising
chicks, female breeding success is limited only Mating brings sperm
by the number of available males. and eggs together, but
the best system for
creating and raising
102 g Behaviour offspring varies greatly.
 SEXUAL SELECTION
the 30-second zoology
All species evolve through
natural selection, and genetic mutations that
increase survival and reproductive success are
3-SECOND DISSECTION more likely to passed on to the next generation. RELATED TOPICS
Choosing the right mate is Sexual selection is the subset of natural See also
important for the future NATURAL SELECTION
selection that favours the traits that improve an
success of any offspring, page 18
so many animals go to
individual’s chance of mating rather than simply
MATING
great lengths to show off surviving. The exaggerated colours, ornaments page 102
their qualities. and behaviours of many species have their roots
in impressing mates and defeating rivals. For
example, the extravagant feathers of the male 3-SECOND BIOGRAPHY
3-MINUTE SYNTHESIS AMOTZ ZAHAVI
Sexual selection often peacock’s tail are long, cumbersome, expensive 1928–2017
results in sexual dimorphism to produce and maintain and likely to catch the Israeli evolutionary biologist
who pioneered the handicap
(males and females looking eye of predators looking for an easy meal, but principle in sexual selection,
and behaving differently), the idea that sexually selected
simply because the best
displaying such a fine train is what shows a features impart a cost and act
peahen that this may be a worthy mate. She as honest signals of mate
strategy for passing on your quality
genes can vary between wants the best genes for her chicks, genes that
males and females. Elephant
will make them successful at finding food and
seals show some of the
most extreme sexual attracting mates of their own. A male who can 30-SECOND TEXT
James Barnett
dimorphism: males can afford to divert resources away from escaping
weigh up to 5,000 kilograms predators and finding food yet still manage to
(11,000 pounds), while
be successful is likely to pass those high-quality
females only reach
about 1,000 kilograms traits on to his offspring, leading to handsome
(2,200 pounds), and all sons and successful daughters. Costly traits
that extra male bulk is are honest signals to prospective mates,
the result of male–male
competition for access
highlighting health and success, as weaker
to females. mates who may want to cheat will be punished Some of the most
by natural selection. beautiful and striking
animal ornamentation
and behaviour has
evolved to impress
104 g Behaviour mates and warn rivals.
 SPERM
COMPETITION
the 30-second zoology
Males and females of many
species compete to get access to the most
desirable partner. This competition does not
3-SECOND DISSECTION necessarily stop once mating is complete, and RELATED TOPICS
Competition between males may continue to compete through their See also
males continues after NATURAL SELECTION
sperm. When racing to the egg, the healthiest
mating, as sperm race to page 18
make sure they are first to
sperm is likely to be one that has the best
MATING
reach the egg; the winner chance of fertilization. By mating with multiple page 102
isn’t decided until the egg males, a female can stack the deck towards her
is fertilized. SEXUAL SELECTION
eggs being fathered by the male with the best page 104
genes. But males are not passive competitors,
SEX ALLOCATION
3-MINUTE SYNTHESIS and they have developed tactics to ensure that page 108
Communities of chimps they will be the successful father. To increase
have multiple males their chances, males from species with high
competing to mate with 3-SECOND BIOGRAPHY
multiple females, but
levels of sperm competition normally have larger
ANGUS JOHN BATEMAN
gorillas live in groups testes. Some species have enormous sperm: 1919–96
dominated by a single very those of the fruit fly Drosophila bifurca can be British geneticist who
pioneered Bateman’s principle
large silverback male who
56 millimetres (2¹/5 inches) long when unwound, that male reproductive success
guards the females from in most species varies more
rivals. Chimps have 20 times the length of the flies themselves. than that of females
enormous testes, whereas Other species may use mechanical or chemical
those of the silverback are tactics to remove or disable the sperm of rivals,
relatively tiny. Larger 30-SECOND TEXT
testes mean more sperm,
and some insects even plug the female’s James Barnett
and this is a tactic to reproductive tract to stop her from mating again.
overwhelm rivals with Females also play a role in determining which
sheer numbers – sperm are successful. Spermicidal agents in her
something gorillas do
not have to worry about.
reproductive tract may kill a large proportion
Intriguingly, human testes of the spermatozoa, weeding out the weak
are proportionally or undesirable.
somewhere in the middle.
Although thousands of
sperm may start the
race to the egg, only
106 g Behaviour one can be successful.
 SEX ALLOCATION
the 30-second zoology
Animals produce offspring for a
single purpose: to propagate their genes into
the next generation. As humans, we may assume
3-SECOND DISSECTION that the (roughly) 1:1 ratio seen between our RELATED TOPICS
When animals produce sexes is simply a property of the equal chance See also
offspring, males and NATURAL SELECTION
of a sperm bearing an X or a Y chromosome
females may have different page 18
benefits or costs, and many
fertilizing an egg, but there is also an
SEXUAL SELECTION
species can alter the sex evolutionary explanation. If one sex becomes page 104
ratio of their progeny. more common, then it will have a reduced
SPERM COMPETITION
relative chance of breeding, so evolution would page 106
select for the rarer sex, bringing things back
3-MINUTE SYNTHESIS
Sex ratios may at first to equilibrium. This assumes that the likely
appear to be random, but reproductive success of each sex (and the cost 3-SECOND BIOGRAPHIES
RONALD FISHER
in certain species females of rearing each sex) is equal. It is not always so. 1890–1962
have the ability to skew the
sex ratio of their offspring.
In harem-breeding species (such as red deer, British statistician who developed
a theory of why sex ratios in
In African wild-dog groups, where one male guards several females) male most animals are close to 1:1
for example, the dominant reproductive success is highly skewed towards WILLIAM D. HAMILTON
female is assisted by her 1936–2000
a small number of dominant males, whereas
sons who stay in the pack British evolutionary biologist,
and help to defend and female reproductive success is not limited by much influenced by Fisher, who
revolutionized our understanding
feed the next generation. mate availability. A son represents a high-stakes of extraordinary sex ratios
In small groups where more bet with only the highest-quality sons likely
helpers would be more
to breed, but, when they do, they sire many
useful, dominant females
offspring. Daughters are almost guaranteed 30-SECOND TEXT
produce more male-skewed James Barnett
sex ratios in their pups. to reproduce but are limited in the number of
offspring they can produce. Not surprisingly,
Animals reproduce to
smaller, younger mothers tend to produce increase the proportion
more female offspring, thereby maximizing of their genes in the next
their chances of spreading their genes to the generation but, depending
succeeding generation. on circumstance, sons and
daughters may differ in
their chances of
108 g Behaviour reproducing.
 g
ECOLOGY
 ECOLOGY
GLOSSARY

abiosis The condition of being of non- their host cannot extract from their food or
living origin. synthesize themselves.

Allee effect For many species being at low coevolution The reciprocal evolutionary
density is beneficial, reducing competition interaction between two or more species,
and allowing faster reproduction. However, with a change in one selecting for adaptation
on occasion, species benefit from neighbours, in the other, which again leads to a continual
to overcome host defences or to provide cycle of change and response.
many eyes to look out for enemies. Here at
low densities they do less well than would commensal species Species that take
be expected. Some suggest that the very resources from another without causing it loss.
rapid decline of the passenger pigeon was
in part caused by the Allee effect. competitive exclusion principle The concept
that no two species living in the same space
allogenic engineers Ecosystem engineers can have identical ecological requirements;
that alter their environments through their one will always outcompete the other.
behaviours, such as digging through soil or
by building dams. ectoparasite A parasite that dwells on the
outside of its host, such as fleas and lice.
aposematic coloration Bright coloration
that warns predators that the potential endoparasite A parasite that lives inside its
victim may be poisonous, dangerous or host, such as tapeworms and viruses.
distasteful.
energetics The flow of energy through an
autogenic engineers Ecosystem engineers ecosystem, usually starting with sunlight
that alter their environments by their and ultimately dissipated as heat, after
presence – trees or corals are examples. passing through a food chain as one
individual eats another.
bacterial symbionts Bacteria that rely
upon their host for survival, and from facultative relationships Interactions between
which the host benefits. Typically these species in a mutualism where both will survive
bacteria may help animals digest their in the absence of the other, even if they would
food, providing essential nutrients which do better together. This is usually contrasted

112 g Ecology
with obligate relationships, where both mammals such as wolf, beaver and lynx to
species are required for each other’s regions where they had been exterminated.
survival, such as some specialist plant–
pollinator interactions. scramble competition When a limited resource
is equally available to all individuals, so that the
inter/intraspecific competition amount of food available to each declines as
Competition is the struggle between the carrying capacity of the resource is
individuals for resources such as food or approached. By contrast, in contest competition,
hiding places. This can be with members of some individuals dominate the resource and
the same species (intraspecific) or with always get enough, while others lose.
other species (interspecific).
speciation The process by which new species
monotremes A group of mammals that lay are formed when genetically isolated.
eggs, but also feed their young milk. The
only extant monotremes are the platypus trophic cascades Events that occur in food
and four echidna species. chains where a change in the abundance of a
predator species flows through the system,
parasitoids Typically insects (usually wasps) changing the numbers of herbivores, and
that lay their eggs on or inside other insects. therefore indirectly affecting the abundance
The larvae act as parasites, but eventually kill of plants. The concept of trophic cascades
their hosts when they emerge as adults. explains why the loss of top predators in
ecosystems is particularly damaging.
primary productivity The synthesis of
complex organic compounds from carbon vector species Animals that pass a disease
dioxide and water, mainly through the from one host to another, such as mosquitoes.
process of photosynthesis. In essence
primary productivity is the amount of plant Wallace’s Line An imaginary divide between
biomass produced in a given area. Australasia and Asia, which demarcates
regions with very different flora and fauna.
rewilding The restoration of an area to a
condition more as it once was before the zoonoses Diseases passed from animals to
influence of people. In recent years, rewilding people, such as Ebola, from bats, and anthrax,
efforts have focused on reintroducing large from cattle.

Glossary g 113
 8 May 1936 1959 1992
Born in Sydney, Australia Becomes a lecturer in Elected as a foreign
applied mathematics associate of the United
at Harvard University, States National Academy
1956/1959 Massachusetts, USA of Sciences
Graduates with a BSc
in chemical engineering
and theoretical physics 1962 1995–2000
followed by a PhD in Becomes a lecturer at Serves as chief scientific
theoretical physics from the University of Sydney adviser to the UK Office
the University of Sydney, and is later promoted to of Science and
Australia professor of theoretical Technology
physics

1996
1973 Appointed Knight
Appointed professor of Bachelor for services
zoology, Princeton to science; awarded
University, New Jersey, the Crafoord Prize by the
USA Royal Swedish Academy
of Sciences for
contributions to the
1979 study of biodiversity
Awarded a fellowship of
the Royal Society, UK
2000–5
President of the Royal
1988–95 Society
After relocating to the UK
serves as a Royal Society
research professor, jointly
at the University of
Oxford and at Imperial
College, London

114 g Ecology
ROBERT MAY

Robert McCredie ‘Bob’ May made many contributions to mathematical

was born in 1936 in Sydney, Australia. As a population ecology, notably highlighting the
boy he excelled in science, later attending effects of chaos on population dynamics. This
the University of Sydney to study chemical work was hugely influential, helping link simple
engineering and physics before completing ecological processes of reproduction and
a PhD there in theoretical physics. This was mortality with complex and often unpredictable
followed by postdoctoral work at Harvard outcomes. May later turned to questions of
University before a return to Sydney where disease transmission, estimating how many
he became professor of physics. It was at this species are on Earth, conservation and over-
time that May became interested in ecological harvesting, bringing a fresh mathematical
questions, in part influenced by the movement viewpoint to subjects that are of immense
for social responsibility in science. importance. Later in his career he applied these
While a successful physicist, May had his ideas to banking, using ecological perspectives
greatest impact in population ecology. His first to provide institutions such as the Bank of
ecological work investigated ideas of how the England with insights into how global financial
stability of ecosystems is influenced by their crashes might best be avoided in the future.
complexity. Many had argued that increased In 1988 May moved to Britain, holding a
numbers of species in an ecosystem resulted Royal Society professorship jointly at Imperial
in greater resistance to change, but May’s College and Oxford University. He has won
mathematical approach showed that this was many prestigious awards, including the Royal
not necessarily so and that, counterintuitively, Swedish Academy’s Crafoord Prize, which
simpler systems were more robust. This opened recognizes disciplines not covered by Nobel
a hugely important debate which has helped categories. May was knighted in 1996 and
explain what it is about patterns of species appointed to the House of Lords in 2001,
interactions in nature that allows complex choosing the title Baron May of Oxford.
ecosystems to persist. May’s influence has been enormous. He was
May took a sabbatical in the UK, where he chief scientific adviser to the UK government and
spent time at Imperial College with noted head of the Office of Science and Technology
ecologist Sir Richard Southwood, then went and president of the Royal Society. Currently
to Princeton, where in 1973 he was appointed he is an Emeritus Professor of the University
professor of zoology. While at Princeton May of Oxford and Fellow of Merton College, Oxford.

Mark Fellowes

Robert May g 115

 BIOGEOGRAPHY
the 30-second zoology
There are estimated to be more
than 10 million species, but they are not spread
equally across the world. Biogeography
3-SECOND DISSECTION attempts to explain why this is so. One obvious RELATED TOPICS
Species distribution is answer is that humankind has hugely simplified See also
explained by a complex ALFRED RUSSEL WALLACE
ecosystems, and fewer species are found where
series of interacting page 14
factors, from speciation
people have had the greatest impact. Once
E. O. WILSON
(how genetically isolated we take that into account we still see broad page 92
animals evolve into distinct patterns in species richness. Understanding
species) and plate tectonics COMPETITION
these helps zoologists uncover the ecological page 118
to energy flow and ecology.
and evolutionary processes that cause these
PREDATION
differences. One pattern is the latitudinal page 122
3-MINUTE SYNTHESIS gradient in numbers of species: the closer to
MUTUALISMS
Between the Indonesian the equator we are, the more species we find. page 126
islands of Bali and Lombok
is ‘Wallace’s Line’, the most
This is largely the result of energy levels; KEYSTONE SPECIES
famous of biogeographical increased levels of solar radiation and rainfall page 128
boundaries. While only found as we move away from the poles allow
35 kilometres (22 miles)
an increase in primary productivity (plant
apart, these islands belong 3-SECOND BIOGRAPHY
to different biogeographical growth), which supports more herbivores and, GEORGE EVELYN
zones. East of the line are in turn, more predators and parasites, leading HUTCHINSON
the animals of Australia, 1903–91
to increased diversity. Another simple rule is British ecologist whose seminal
the marsupials and
monotremes, cockatoos
that of area and isolation. All else being equal, 1959 paper ‘Homage to Santa
Rosalia’, picked out energetics
and kangaroos; west of for patches or islands of a given size, those as a key factor explaining why
biodiversity declines with
the line are the placental more isolated will have fewer species; for distance from the equator
mammals, Asia’s primates, patches of equal isolation, larger patches will
pheasants and big cats.
This boundary demarcates
have more species. Thus smaller more isolated
30-SECOND TEXT
two regions with differing islands will have fewer species. Isolation limits
Mark Fellowes
evolutionary histories which species find islands as they disperse,
driven by changes in sea
and size limits the number of niches that can
levels and isolation.
be exploited. Biogeography explains
why species are where
116 g Ecology they are.
 COMPETITION
the 30-second zoology
In the absence of predators
and disease, animal population sizes are
limited by the availability of resources. At low
3-SECOND DISSECTION sizes populations can grow exponentially, as RELATED TOPICS
Resources, and competition resources are easy to find – we witness this See also
for those resources, limits HERBIVORY
when pests such as locusts invade a new region.
population growth; with page 120
no competition our planet
As their numbers reach plague proportions,
PREDATION
would be covered by the however, individuals have to compete for food, page 122
offspring of a single E. coli slowing down how quickly they can grow and
in less than two days. MUTUALISMS
reproduce, until the population reaches its page 126
carrying capacity, where birth rate is balanced
by death through lack of resources. Competition
3-MINUTE SYNTHESIS does not have to be fair; it can have winners and 3-SECOND BIOGRAPHIES
Competition for food, WARDER CLYDE ALLEE
losers (contest competition), where a dominant 1885–1955
space and mating
opportunities can be within
individual gains resources and others lose out. American ecologist, after
whom the Allee effect is named
(intraspecific) or between In contrast, with scramble competition everyone
GEORGY FRANTSEVICH
(interspecific) species. One loses. Here competitors are more equal and GAUSE
hugely influential idea in
so all take a proportion of the food available, 1910–86
interspecific competition Soviet biologist who developed
is that of the competitive leading to starvation when the resources aren’t the competitive exclusion
exclusion principle, which plentiful enough to maintain every individual. principle
suggests that when two A key tenet of competition theory is that it is
species are competing for
the same limiting resource
density dependent, where increased numbers 30-SECOND TEXT
they cannot coexist; one results in increased competition. It is worth Mark Fellowes
will eventually win, noting that this isn’t always the case, however.
excluding the other. The Allee effect shows that at low densities
However, we rarely see
this in nature, as who
populations can do less well than might be
wins is not often expected, as larger numbers working together
determined by any one can help access resources that would otherwise
single factor. The world is
be inaccessible. Sometimes it’s better to have Competition is
a complicated place.
a few neighbours than none at all. everywhere. Without
it, there are few limits
118 g Ecology to population growth.
 HERBIVORY
the 30-second zoology
Why is the world green? This
superficially simple question was posed in
1960 by three ecologists who wondered why
3-SECOND DISSECTION herbivores have not completely over-exploited RELATED TOPICS
Reliant on a plant-only diet, the plants they consume. They argued that See also
herbivores are trapped COMPETITION
plants survive because predators limit herbivore
between predators (some page 118
of which are deliberately
numbers, a top-down process. This is certainly
PREDATION
attracted by plants to true in some circumstances – for example, page 122
help defend them) and where sea otters were hunted to extinction,
poor-quality food. MUTUALISMS
sea urchins flourished and destroyed kelp page 126
forests. Others suggested that predators are
KEYSTONE SPECIES
3-MINUTE SYNTHESIS less important than they might appear. Plants page 128
Herbivores have evolved are not just passive victims waiting to be
a wide range of means to consumed; they have a range of physical and
counter the defences 3-SECOND BIOGRAPHIES
plants put up against them. chemical defences that mean that they are
NELSON HAIRSTON SR
Most rely upon bacterial just very poor-quality food. Herbivores have 1917–2008
symbionts (bacteria living to overcome spines and thorns, saps and latex, FREDERICK SMITH
symbiotically within the 1920–2012
before they can even begin to feed; and when
herbivore) to aid the LAWRENCE SLOBODKIN
digestion of plant material, they do, they have to deal with silica (which 1928–2009
and these make up a wear down mandibles) and a complex chemistry American zoologists and
ecologists who popularized the
significant proportion of which can both poison the herbivore and further concept of trophic cascades, in
their microbiome. Others, which predators benefit plants
such as proboscis monkeys
reduce the nutritional quality of the plant by by removing herbivores

and ruminants such as binding to essential nitrogen compounds and

cattle, have more rendering them inaccessible. So the world may,
complicated, slow digestive 30-SECOND TEXT
in fact, be green because herbivore numbers Mark Fellowes
systems. Others just take
their time; there’s a very are limited by poor nutrition. Whether it’s
good reason why sloths top-down or bottom-up processes keeping the Being a herbivore isn’t
are slothful. world green, herbivory has driven the evolution easy. Plants may
of plant chemistry, giving humanity some of appear defenceless,
its most utilized stimulants (caffeine), flavours but they hide a complex
(chilli) and drugs (cocaine, heroin). chemistry to keep
120 g Ecology enemies at bay.
 PREDATION
the 30-second zoology
Predators kill their prey. Both
killers and killed interact in ecological and
evolutionary time, coevolving defence and
3-SECOND DISSECTION counter-defence. Some of the most glorious RELATED TOPICS
For both hunter and animals alive have been shaped by their lives as See also
hunted, predation is a fact COMPETITION
hunter or hunted, with evolution honing traits
of life – and this includes page 118
predation of predators all
that increase success. Predators become fast,
HERBIVORY
the way to the top of the masters of camouflage and concealment and page 120
food chain. heavily weaponized with claws, teeth or venom.
MUTUALISMS
Each is an adaptation that increases the success page 126

3-MINUTE SYNTHESIS
of predation, and, in turn, this evolutionary
KEYSTONE SPECIES
Predators and prey do not pressure has selected prey that are fast, agile, page 128
always coexist. Introduced hidden, armoured, vigilant and sometimes
predators have wreaked poisonous, with bright aposematic colours that
havoc on biodiversity in 3-SECOND BIOGRAPHY
many parts of the world.
warn predators that they are not good to eat.
JOHN RICHARD KREBS
The domestic cat is widely Some prey cooperate, using signals to alert 1945–
considered to be one of the others to the presence of a threat, while others British ornithologist, who,
along with Richard Dawkins
most damaging invasive
bluff, mimicking larger or more dangerous (1941–), popularized the
species, having caused 63 concept of the ‘life-dinner
known recent extinctions animals. This escalation of traits that affect the principle’
of bird, mammal and reptile likelihood of eating or being eaten is essentially
species. The best-known an arms race. Some argue that selection
example is Lyall’s wren, 30-SECOND TEXT
a flightless New Zealand
pressure is asymmetrical, with stronger selection Mark Fellowes
bird species that was lost for escape. This is the ‘life–dinner principle’.
to the world through cat Prey that fail to escape lose their lives and leave
predation in 1894. no offspring, whereas a hunter that fails to kill
just loses a meal. This means that there may
be limits to the pace of coevolution between
predators and prey, but it also ignores the fact
that missing enough meals also ultimately Predators and prey
leads to death. are entwined in a dance
of natural selection
122 g Ecology and survival.
 PARASITISM
the 30-second zoology
Whether ectoparasitic (such as
lice, fleas or fungi) or endoparasitic (such as
flukes, tapeworms, bacteria and viruses) one
3-SECOND DISSECTION thing common to all parasites is that the RELATED TOPICS
Parasites are species that relationship with the host only goes one way. See also
live on or in other species, COMPETITION
Their life cycles vary greatly in complexity,
where the parasite benefits page 118
by consuming nutrients
but each life stage is exquisitely adapted to
MUTUALISMS
from the host, and the transmission (infecting new hosts, often page 126
host, in turn, is harmed. involving the use of vector species) and survival
(avoiding the host’s immune or behavioural
3-MINUTE SYNTHESIS
defences). Parasites are ubiquitous, and almost 3-SECOND BIOGRAPHIES
ALPHONSE LAVERAN
Parasites are hidden, everyone will at some point have been a host, 1845–1922
but their effects are even if only to the innocuous eyelash mite. French doctor who suggested
everywhere. A major threat that a protist caused malaria;
Most parasites cause relatively minor damage to he was awarded the 1907 Nobel
to human health comes Prize for Physiology or Medicine
from zoonoses, diseases
healthy hosts, but the consequences of infection
which jump the species can be severe. While we are familiar with the CARLOS FINLAY
1833–1913
barrier from animals to effects of parasites on humans – malaria, for Cuban doctor who suggested
humans. Diseases such as
example – they can also have disastrous effects that mosquitoes were vectors
HIV and Zika are thought of diseases such as malaria
to be caused by viruses on animal populations. One of the greatest
TU YOUYOU
moving from monkeys to threats to amphibians comes from the chytrid 1930–
people. The Spanish flu fungus, which threatens many species across Chinese chemist who showed
pandemic of 1918–20 killed that an extract from a plant
up to 100 million people,
the world with extinction. The fungus may have used in Chinese traditional
medicine, artemisinin, was
and, more recently, been spread from Africa with exports of the effective in controlling malaria;
enormous efforts have African clawed frog, which was used between she received the Nobel Prize for
Physiology or Medicine in 2015
been spent monitoring the the 1930s and 1950s for pregnancy testing.
spread of bird flu through
fears that another
Parasites can, however, be beneficial. Cassava
pandemic could strike. is threatened by the invasive cassava mealybug, 30-SECOND TEXT
Mark Fellowes
but the release of specialized insect parasites
(parasitoids) has helped bring it under control, Parasites are the most
saving the staple crop of millions of people. intimate of species,
supremely adapted to
124 g Ecology their host’s biology.
 MUTUALISMS
the 30-second zoology
‘Nature red in tooth and claw’,
taken from Tennyson’s poem In Memoriam,
are words that have often been used to describe
3-SECOND DISSECTION the reality of nature: you eat or you are eaten; RELATED TOPICS
Not all interactions in you win or you die. This view dominated ecology See also
nature are brutal or one COMPETITION
and evolutionary biology for many decades
sided; some species have page 118
evolved over time to
until that perception was whittled away by the
HERBIVORY
cooperate for their recognition that cooperation between species, page 120
mutual benefit. known as mutualism, is widespread in nature.
PREDATION
While this cooperation arises from self-interest, page 122

3-MINUTE SYNTHESIS
with both species benefiting, over evolutionary
KEYSTONE SPECIES
Without mutualistic time some mutualisms have become obligate, page 128
interactions our society where survival of the interacting species
ECOSYSTEM ENGINEERS
would not exist. requires the presence of both. In tropical page 130
Mutualisms drive the
production of crops (with
forests, fig trees are keystone species, providing
pollinators) and livestock resources for numerous other species. The
3-SECOND BIOGRAPHY
(the herbivores we eat and existence of each of the approximately PIERRE-JOSEPH VAN
milk need bacteria to digest
900 fig species is predicated on the presence BENEDEN
their food plants). Some 1809–94
scientists argue that, of a pollinating fig wasp, with almost every
Belgian zoologist who, in 1876,
because of artificial tree species having a single specialist pollinator introduced the term mutualism
breeding for traits such as species. Neither fig tree nor fig wasp would
productivity and docility
over time, most of the
survive without the other. Other mutualisms
30-SECOND TEXT
animals and plants we are facultative, where one interacting species Mark Fellowes
currently farm would not can survive in the absence of the another but
survive without us, and we, will benefit if they are together. In many parts
in our turn, rely on them
for our own survival.
of the world, species of true bug (such as
aphids) are tended by ants. The ants protect
the insects from predation while benefiting
from the honeydew (a sugar-rich secretion)
produced by the bugs. Sometimes Nature
allows both sides to win
126 g Ecology the game of life.
 KEYSTONE SPECIES
the 30-second zoology
A keystone holds an arch together;
without it, everything collapses. In ecosystems
the same critical role is provided by keystone
3-SECOND DISSECTION species, a term defined by Bob Paine in 1966 RELATED TOPICS
Out of all proportion to after studying rocky-shore intertidal communities See also
their abundance, keystone COMPETITION
in Washington State, USA. Paine found that
species determine the page 118
structure and stability of
removing a species of starfish resulted in a
HERBIVORY
ecosystems, and their loss simplification of the natural community with page 120
can cause lasting damage almost half of species ultimately disappearing,
to biodiversity. PREDATION
because, by predating mollusc species that would page 122
otherwise have outcompeted others, the starfish
MUTUALISMS
3-MINUTE SYNTHESIS
maintained species diversity. Since his discovery, page 128
Keystone species are many examples of keystone species have been
ECOSYSTEM ENGINEERS
immensely important found. Perhaps the most impressive example is page 130
within their environments,
the grey wolf, following its reintroduction into
but throughout history
humans have Yellowstone National Park, Wyoming, USA. The
3-SECOND BIOGRAPHY
disproportionately wolf had been exterminated in the region by the ROBERT ‘BOB’ T. PAINE
removed them from 1930s, allowing populations of their prey species, 1933–2016
ecosystems. We have a American zoologist who
tendency to target large
elk, to grow rapidly. Elk overgrazed saplings, and developed the concept of
predators, whose presence this had a cascade of negative effects, including a keystone species, influencing
generations of ecologists and
prevents a small number of reduction in songbird diversity, fewer beavers and conservation biologists
strong competitors from simplification of river flow and increased erosion.
dominating ecosystems. If
we are to protect or rebuild
The wolf’s reintroduction in the 1990s helped
30-SECOND TEXT
ecosystems, rewilding has turn back the clock, as predation directly (elk Mark Fellowes
to include the return of numbers) and indirectly (elk behaviour) reduced
keystone species. The
levels of tree browsing. In consequence, songbird
enormous and beneficial
effect of a handful of diversity and beaver numbers increased, and
wolves reintroduced to rivers are returning to their former complexity.
Yellowstone National Park The surprising thing? There are only around Top predators help
stands as a testament to
this approach.
100–150 wolves in Yellowstone, an area of almost ecosystems to function;
9,000 square kilometres (3,500 square miles). their presence benefits
128 g Ecology biodiversity.
 ECOSYSTEM
ENGINEERS
the 30-second zoology
Animals are not simply passive
residents in an abiotic world; they shape
the world, for themselves and other species.
3-SECOND DISSECTION All species make small changes to their RELATED TOPIC
Ecosystem engineers are surroundings, but in 1994 Clive Jones and See also
species that modify their HABITAT LOSS
colleagues suggested that some organisms have
local environments, greatly page 140
changing the availability
inordinately large effects on their environments
of food and habitats and consequently for the species around them.
that species other than They called such species ecosystem engineers. 3-SECOND BIOGRAPHIES
themselves can exploit. CHARLES DARWIN
These species can change one element of the 1809–82
abiotic environment into another by mechanical British naturalist who studied
the rate at which earthworms
3-MINUTE SYNTHESIS means (allogenic engineers) or by their own turn over soil by measuring
how heavy stones sank into
The greatest ecosystem growth and presence (autogenic engineers). the ground over time, an early
engineer of all is Beavers are allogenic engineers. By building example of thinking about
humankind. No other ecosystem engineers; his book
single species has altered
dams across rivers they slow the passage of The Formation of Vegetable
Mould, through the Actions
its environment as we water, creating new ponds and lakes. In doing so of Worms was his last
have, from the composition they provide rich habitats for fish that prefer still MOSHE SHACHAK
of the atmosphere to
waters, reduce erosion and flooding downstream 1936–
plastic pollution at the SIR JOHN LAWTON
greatest ocean depths. and enhance nutrient capture for the multitudes
1943–
While nature’s ecosystem that live in the sediment. By changing the nature CLIVE G. JONES
engineers alter of the ecosystem, beavers benefit many other 1951–
environments in a way Ecologists who wrote the 1994
that benefits many species,
species. Corals are autogenic engineers. The paper ‘Organisms as Ecosystem
physical structure of their living and dead forms Engineers’, which introduced
we have engineered the the idea of ecosystem
world to benefit a handful creates a habitat for massed schools of fish, engineering
of domesticated and making coral reefs some of the most diverse
commensal species.
Most ecosystem engineers
places on Earth. Ecosystem engineers are all 30-SECOND TEXT
increase the diversity of around us: moles and earthworms turn soil over Mark Fellowes
life in their communities, in our gardens, woodpeckers drill holes in trees,
in contrast we simplify and
cattle and deer leave tracks which fill with water. Life has moulded the
homogenize the living world.
Each creates a changed environment for new planet, providing the
species to exploit. oxygen in the air and
130 g Ecology the soil on the ground.
 g
CONSERVATION & EXTINCTION
 CONSERVATION & EXTINCTION
GLOSSARY

Anthropocene The proposed term for the disease vector An organism that carries and
current epoch or geological time period of transmits an infectious pathogen into another
the Earth, beginning with the point from organism. Mosquitoes and ticks are vectors
which human influence altered the climate for many diseases.
and geological, hydrological, biospherical
and other environmental processes. ecosphere The terms for all the ecosystems
on our planet.
bioaccumulation The gradual accumulation
of contaminants within or on an organism. maximum sustainable yields The largest
number of individuals that can be harvested
biotic homogenization The process by from a population without causing declines
which species found within two or more over time.
areas become similar over time because of
species invasions and extinctions. nature deficit disorder Humans are losing
their connection with nature. This
bush meat Term for meat obtained from detachment, or so-called ‘nature deficit
hunting or trapping non-domesticated disorder’, is negatively affecting our health
animals, a widespread practice that and well-being and has implications for
threatens native wildlife diversity. conservation worldwide. With more people
living in urban areas, our interactions are
bycatch The unintended fish or other shaped by the animals that are able to live
marine animals that are caught, especially alongside us. Many people choose to make
by commercial fishing fleets using their gardens and outside spaces more wildlife
longlines, trawlers, gill nets and purse- friendly. Simple acts like putting up a bird
seine nets is known in the fishing industry feeder can help increase people’s daily
as bycatch. It can include different species interactions with wildlife.
entirely, the wrong sex, or juveniles of the
target species. Marine life can include phenological asynchrony A mismatch in the
turtles, dolphins and seabirds that are timing of lifecycle events between species
caught with the intended species, only to that rely on each other to survive.
be discarded overboard.

134 g Conservation & Extinction

reproductive isolation Mechanisms which
prevent members of a species from
breeding

rewilding The restoration of an area to

a condition more as it would have been
before the influence of humans. In recent
years, rewilding efforts have focused on
the reintroduction of large mammals such
as wolf, beaver and lynx to regions where
they had been exterminated.

speciation The process by which new

species are formed.

tragedy of the commons Term describing

the exploitation and depletion of a natural
resource by individuals to their own
advantage without consideration the
common good.

Glossary g 135
 10 September 1944 1985 1991
Born in Doylestown, Receives her PhD in Following extensive work,
Pennsylvania, USA anthropology from City Ranomafana National
University of New York Park is established in
Madagascar
1966
Graduates with 1986
bachelor’s degree in Travels to Madagascar 2003
biology from Hood to search for the greater The Centre ValBio,
College, Maryland, USA bamboo lemur, believed a research institution
at the time to be extinct that aims to promote
environmental
conservation in
Madagascar and
throughout the world,
is founded

2014
Becomes the first woman
to receive the
Indianapolis Prize for
Conservation

136 g Conservation & Extinction

PATRICIA WRIGHT

There are many ways to become to set up the Ranomafana National Park.
interested in science, but Patricia Wright’s In return for not exploiting the resources in
journey is somewhat unusual. As a mother at the forests, local people were provided with
home in Brooklyn, New York, in the 1960s, she schools and healthcare facilities as well as
owned two nocturnal owl monkeys. She was new employment opportunities within the
fascinated by their behaviour and wanted to park. The park now receives over 100,000
learn more about these primates in the wild; visitors each year, bringing much-needed
so, with her husband and daughter in tow, she money into the local economy.
embarked on an expedition to the jungles of With this incredible area given formal
Peru to study them. Nearly a decade later she protection, Wright set about establishing
received her doctorate before continuing her Centre ValBio, a research facility positioned
journey into conservation science. next to Ranomafana National Park. The centre
Wright later set herself the challenge of has enabled exciting research to be carried
trying to locate a species that many considered out throughout Madagascar, but it is also
to be extinct. She travelled to Madagascar, a committed to reducing poverty in the local
country filled with endemic species, on the hunt area to allow for sustainable use of natural
for the greater bamboo lemur. She not only resources. With local conservation clubs and
rediscovered the greater bamboo lemur but she the establishment of ecotourism in the region,
also found another new to science, the golden the local people are gaining an understanding
bamboo lemur. As amazing as these discoveries of the value of conservation.
were, Wright was shocked by the devastation Patricia Wright’s conservation message is
she saw around her. Madagascar had already also being felt at an international level. Each
lost so much of its natural habitat, but with year Centre ValBio welcomes students from
logging threatening the survival of these across the world in Study Abroad programmes,
bamboo lemurs as well as many other animals, and Patricia herself and the research being
she knew she must act. Collaborating with local carried out at the centre have been showcased
people and the Madagascan government, in numerous media outlets, including the 2014
Wright worked to gain support and raise funds film Island of Lemurs: Madagascar.

Rebecca Thomas

Patricia Wright g 137

 CLIMATE CHANGE
the 30-second zoology
Climate change is perhaps the
greatest global threat to both biodiversity
and humanity. The world’s average surface
3-SECOND DISSECTION temperature has increased by 0.9°C (1.62°F) RELATED TOPIC
If we do not act fast to since the late nineteenth century – five of the See also
reduce carbon emissions HABITAT LOSS
warmest years on record have taken place
climatologists predict a page 140
tipping point will be
since 2010 – and by the end of this century
reached from which it will conservative estimates predict a further
take centuries for the increase of 2°C (3.6°F). Increasing levels of 3-SECOND BIOGRAPHY
damage to be undone. WALLACE SMITH BROECKER
carbon dioxide from human activities are leading 1931–2019
to ocean acidification and rising temperatures, American geophysicist, dubbed
the ‘grandfather of climate
3-MINUTE SYNTHESIS causing sea-level rises, changes in rainfall, science’, who popularized the
term global warming
Climate change is taking wildfires, intense storms and glacial retreat.
place so rapidly that many These changes are occurring at such a pace that
species are not able to
adapt to the changing
many species are unlikely to be able to adapt. 30-SECOND TEXT
conditions in which they Vegetation patterns have already changed. In Rebecca Thomas
find themselves. With this temperate regions trees come into leaf weeks
threat we need to take a
earlier than they once did, and temperature
landscape view when we
consider the conservation change also affects the insects that feed on
of species. The world’s them. But the migration behaviour of birds such
natural habitats have as pied flycatchers has not changed, meaning
become increasingly
fragmented, and we need
that they may arrive late for peak caterpillar
to connect these areas up numbers. This phenological asynchrony means
to allow species to alter that they are out of step with their food
their distributions if they resource, reducing their chances of successfully
are to survive the global
impact of climate change.
rearing young. Not all species will lose out,
however. Models predict that many diseases will
move into new regions as rising temperatures Humans are driving
open up suitable habitats for their vectors. climate change through
global warming and its
effects are visible in
138 g Conservation & Extinction every part of the world.
 HABITAT LOSS
the 30-second zoology
Humans are transforming vast
swathes of our planet’s surface at a pace unlike
any other seen in recent geological time, and
3-SECOND DISSECTION habitats are being altered so dramatically that RELATED TOPICS
Human populations are habitat loss is now the greatest cause of global See also
growing exponentially, PATRICIA WRIGHT
species extinction. Throughout human history
putting enormous pressure page 136
on natural habitats and
we have changed the land, mostly for small-
CLIMATE CHANGE
causing the decline and scale agriculture, but more recently we have page 138
extinction of many species created vast mega-cities and industrial-scale
across the world.
agriculture so that today over half of the Earth’s
land surface is no longer natural. This has been 30-SECOND TEXT
Rebecca Thomas
3-MINUTE SYNTHESIS driven by rapid human population growth and
As well as habitat loss, the resulting increase in demand for food and
humans are degrading and consumer goods, pushing many species to the
fragmenting what remains
of our natural areas.
brink of extinction. Forests, the most biodiverse
Improving connections habitats, have been the worst affected by this
between habitat patches devastation. In Madagascar, for example, nearly
and protecting existing
90 per cent of native forest cover has been lost,
areas for wildlife are top
priorities. Some countries threatening many lemur species. Lemurs are
are currently attempting found only here, and with the human population
ambitious rewilding projects increasing, the lemurs’ survival relies on preserving
as well as schemes to
reconnect the fragmented
natural habitats. Even ring-tailed lemurs, one of
landscape, and many of the most widely recognized species, is threatened
those involved are local through habitat destruction. Ring-tailed lemurs
landowners who understand breed well in captivity, and they are very
that reconnecting areas of Loss of native habitat
conservation value will help
adaptable, so reintroduction programmes are directly affects a
many species and provide possible in areas where they have been lost species’ ability to
resilience in the face of – but success in this is dependent on them survive through
climate change.
having a habitat to return to. increased competition
for declining resources,
from food to places
140 g Conservation & Extinction to hide.
 POLLUTION
the 30-second zoology
Almost every human activity
causes some form of pollution, and this, in turn,
causes enormous harm to the natural world as
3-SECOND DISSECTION well as being responsible for many human RELATED TOPICS
Pollution is a global deaths. Large-scale oil spills capture our See also
problem: human activities CLIMATE CHANGE
attention. Thankfully they are rare, albeit
introduce undesirable page 138
contaminants that cause
devastating to local wildlife, but other forms
harm to individuals, of pollution are more hidden and insidious,
populations, ecosystems damaging our climate, destroying the ozone 3-SECOND BIOGRAPHY
and even the whole RACHEL LOUISE CARSON
layer, killing non-target insects, simplifying 1907–64
ecosphere.
ecosystems and even affecting how animals American biologist whose 1962
book Silent Spring brought
develop. Recently awareness has risen of just about the environmental
movement and led to the
3-MINUTE SYNTHESIS how widespread plastic pollution is. Large banning of DDT in many
In 1945 the insecticide DDT plastics in the oceans are regularly ingested by countries and the creation of
became readily available, the US Environmental
and its wide-scale use had
marine mammals and birds. These are not Protection Agency

devastating effects on digested and can prevent them from taking

wildlife. The chemical in food, meaning they will starve. Plastics
became embedded in the 30-SECOND TEXT
also break down into tiny pieces becoming Rebecca Thomas
fat stores of many species.
When they were eaten by microplastics; these are ingested and
their predators the toxin incorporated into the tissues of many species,
accumulated at increasing including the fish we eat. Microplastics have
concentrations, and this
bioaccumulation caused
been found in every habitat in which they have
enormous harm to been looked for, including the abyssal depths.
non-target species. Most They can be eaten by larval insects in rivers,
notably, many birds of prey and as the adults emerge they carry the
suffered, and it was only Chemical contaminants,
after DDT was banned that
microplastics and may be eaten by birds, passing through accidental and
populations of species such the pollution along the food chain. Nowhere deliberate acts, are not
as the peregrine falcon escapes the unwelcome touch of pollution, simply damaging to the
could begin to recover.
and this is the clearest sign that we have truly environment. By entering
entered the Anthropocene. the food chain pollutants
threaten all organisms on
142 g Conservation & Extinction the planet.
 OVER-HARVESTING
the 30-second zoology
Humans have always harvested
wild animals and plants, but advances in
technology and rising human populations now
3-SECOND DISSECTION place immense pressures on many species. Many RELATED TOPICS
Harvesting individuals at are under threat or have become extinct through See also
rates faster than their HUMAN–WILDLIFE CONFLICT
over-exploitation – and not just for food and fur.
populations can recover page 148
leads to over-exploitation,
Some are threatened by demand for trophies
and this is a major threat to and traditional medicine – causing the over-
many wild species. harvesting of animals such as rhinoceroses, 30-SECOND TEXT
Rebecca Thomas
tigers and elephants – and unsustainable
3-MINUTE SYNTHESIS
demand for bush meat from rapidly growing
Over-harvesting is a serious urban populations places a wide range of species
challenge in aquatic in danger. Aquatic environments are perhaps
environments. Many the worst affected, with populations of many
fisheries across the world
are a common resource
long-lived and highly valued fish, including cod
and because of this suffer and tuna, suffering enormously high losses.
from the so-called ‘tragedy Harvesting can be sustainable if species can
of the commons’. No
reproduce at a rate that compensates for
individual person fishing
has the motivation to stop mortality, but once a threshold is passed
once a resource comes reproduction can no longer keep up with removal
close to over-exploitation, rates. These maximum sustainable yields are
because someone else will
simply take the resource
used in the fishing industry to estimate how
instead. This, alongside many individuals can be safely harvested –
the technological which, for slowly reproducing species, can be a
developments that allow very small number – although some criticize this
more fish to be taken
with less effort, means approach as failing to capture the complexity of
that many fish stocks pressures on fish populations. More importantly, Short-term gains are
have collapsed. it requires real political will to agree and enforce impacting on the ability
realistic quotas in international waters, of many species to
something that has been sadly lacking to date. recover their numbers,
tipping them perilously
144 g Conservation & Extinction close to extinction.
 INVASIVE SPECIES
the 30-second zoology
Some species, through human
interference, find themselves outside of their
natural range. Some introductions – pet cats
3-SECOND DISSECTION and house sparrows, for example – have been RELATED TOPICS
A number of the species we deliberate, but most, such as zebra mussels See also
know and love are invasive, HUMAN–WILDLIFE CONFLICT
being transported across the oceans in the
especially in more page 148
urbanized areas, but they
ballast water of ships, have been accidental.
URBAN ANIMALS
can be a big driver of Many such species have little obvious effect page 150
biodiversity loss. on their new homes, but some spread in a way
that greatly impacts native inhabitants, human
health or the economy, and these are known 30-SECOND TEXT
3-MINUTE SYNTHESIS Rebecca Thomas
Many species have been as invasive species. Such invaders can be
introduced outside of their particularly damaging on islands. In the late
native ranges, but this does 1940s the brown tree snake found its way to the
not make them invasive.
To get this title they need
Pacific island of Guam, most likely by stowing
to cause harm, and only away on military aircraft. A lack of predators and
around 10 per cent of competitors allowed them to thrive, and today
introductions become
they are devastating the island’s ecology. It can
problematic. Unfortunately,
some of the most damaging be very difficult to remove invasive species once
species – such as cane they become established, although there have
toads, cats, Nile perch and been some success stories. Invasive rodents
rosy wolf snails – have been
have been removed from Teuaua Island in French
released deliberately with
dreadful ecological and Polynesia, allowing the native sooty terns to
economic consequences. nest on the island without the threat of rats
Introducing species The accidental or
predating their young. However, the cost of
can result in biotic deliberate introduction
homogenization, reducing
removing invasive species is often much greater of species to areas that
natural differences in than the cost of prevention, underlining the lack the checks and
biodiversity between fact that it is better to avoid their introduction balances of their
environments.
in the first place. natural range has
resulted in some
notorious losses
146 g Conservation & Extinction of biodiversity.
 HUMAN–WILDLIFE
CONFLICT
the 30-second zoology
For many, a connection with
nature is part of what makes life special and
memorable. For these people, contact with
3-SECOND DISSECTION wildlife is seen as a boon; holidays are focused RELATED TOPICS
Human–wildlife conflict on natural areas, wildlife documentaries are See also
is increasing as human HABITAT LOSS
enjoyed and, even on our doorsteps, providing
populations grow and our page 140
tolerance for crop damage,
food for garden birds and other wildlife is
URBAN ANIMALS
disease and wildlife something many people do. But when humans page 150
interference diminishes; and wildlife mix conflicts can arise, with wild
because of this many
animals seen as a threat to livelihoods, health
species face persecution.
and well-being. For those who rely on 30-SECOND TEXT
Rebecca Thomas
agriculture, crop losses mean financial losses,
3-MINUTE SYNTHESIS and human–wildlife conflicts around farming
Numerous strategies to can be devastating. Elephants epitomize this
reduce human–wildlife
conflict have been used
duality. For ecotourists, elephants are one of
when the species concerned the most charismatic of mega-fauna, a species
are of conservation value. worth travelling around the world to see in the
From lethal control to
wild. But elephants can also cause extensive
compensation payments,
each aims to minimize the damage when raiding agricultural areas to find
contact between the parties food, causing damage by trampling crops while
involved. Some of the most moving through the fields. This can have serious
successful examples have
been in providing
consequences for the local human communities,
alternative livelihoods to and as a result persecution does take place. But
local people through working with local knowledge is often the best
ecotourism. If people are method for reducing conflict. Elephants do not
able to make their livings by
protecting the species that
like plants containing capsaicin, and they also
would otherwise have been have an aversion to bees, so farmers use
causing problems then chilli-plant fences and beehives to deter them. Sharing the planet with
communities are much more
accepting of their presence.
other species requires
strategies that promote
mutual harmony and
148 g Conservation & Extinction sustainable solutions.
 URBAN ANIMALS
the 30-second zoology
Humans have been modifying
the landscape for thousands of years, but only
within the past century have we been creating
3-SECOND DISSECTION densely inhabited towns and cities. With over RELATED TOPICS
Across the world cities 50 per cent of the global human population now See also
are becoming bigger and NATURAL SELECTION
living in urban areas, many animals are learning
more numerous, and many page 18
animals are learning to
to live alongside the city dwellers. Our built
HUMAN–WILDLIFE CONFLICT
adapt and exploit the environments can be tough for animals – page 148
habitats and resources generally, as urbanization increases biodiversity
that they provide.
is reduced – but some are finding ways to live,
even thrive, among people. Mostly these are 3-SECOND BIOGRAPHIES
KATHARINE BYRNE
3-MINUTE SYNTHESIS generalists such as rats and foxes, but alongside unknown
Speciation (the process by the ubiquitous sparrows and starlings we now RICHARD NICHOLS
which genetically isolated 1959–
find species as special as leopards and langurs,
animals evolve into distinct Researchers who undertook a
species) is happening
penguins and peregrines, and for some species study of London Underground
mosquitoes in the 1990s
within our own time. urban areas are critical for their conservation.
Mosquitoes first colonized Under this novel evolutionary pressure animals
the London Underground
are rapidly adapting genetically to urban life, 30-SECOND TEXT
when the tunnels and
stations were used as especially in places where barriers restrict Rebecca Thomas

bomb shelters during the movement between populations – one perhaps

Blitz. Research during the surprising example of which is the London
1990s revealed that the
Underground mosquito Culex pipiens molestus. As ever-increasing
Underground mosquitoes numbers of us become
had, by remaining in Many birds, too, show how species can change
urban dwellers, our
reproductive isolation, as they live alongside humans. Ornithologists
formed a subspecies, interactions with other
have discovered that urban populations of
distinct even from those species are being
occupying other parts of
the European blackbird sing at a higher pitch shaped by those
the city, because they were (because of traffic noise) and have shorter animals that are able
unable to interbreed with beaks (because food types differ) and no longer to live alongside us.
other populations.
migrate during winter (because food is available Losing connection with
all year round). Cities are the newest crucibles of nature has implications
evolutionary change. for conservation
150 g Conservation & Extinction world wide.
 g
APPENDICES
 RESOURCES

BOOKS AND ARTICLES

Amphibian (Eyewitness series) The Great Big Book of Snakes
Barry Clarke and Reptiles
(Dorling Kindersley, 2005) Barbara Taylor
(Hermes House, 2006)
Animal Fact File: Head-To-Tail Profiles
of Over 90 Mammals Herpetology, An Introductory Biology
Tony Hare of Amphibians and Reptiles
(Facts on File Inc., 1999) Laurie J. Vitt and Janalee P. Caldwell
(Elsevier Science, 2013)
‘Culex pipiens in London Underground
tunnels: Differentiation between surface and Insect Evolutionary Ecology
subterranean populations’ M. D. E. Fellowes, G. J. Holloway and J. Rolff
Katharine Byrne and Richard A. Nichols (CABI Publishing, 2005)
Heredity 82 ( Pt 1)(1):7–15, February 1999
Mammals
DOI: 10.1038/sj.hdy.6884120
Juliet Clutton-Brock
The Diversity of Life (Dorling Kindersley/Smithsonian Handbooks
Edward O. Wilson series, 2002)
(Penguin, 2001)
Ornithology
Extraordinary Birds: Exquisite Selections Frank B. Gill
of Art and Ornithology from the American (W. H. Freeman & Co., 2006, 3rd edn)
Museum of Natural History Library,
Ornithology in Laboratory and Field
Essays & Plates
Olin Sewall Pettingill
Paul Sweet, including a chapter by
(Academic Press, 1985, 5th edn)
Peter Capainolo
(Sterling Signature, 2013) Reptile (Eyewitness series)
(Dorling Kindersley, 2005)
Fishes of the World
Joseph S. Nelson Sharks of the World
(John Wiley & Sons, 2006, 4th edn) Leonard Compagno, Marc Dando
and Sarah Fowler
(Princeton University Press, 2005)

154 g Resources
 ONLINE READING
Silent Spring All the World’s Primates
Rachel Carson Fully referenced online resource covering all 505
(Houghton Mifflin, 2002, anniversary edn; first species of primates
published in 1962) www.alltheworldsprimates.org/Home.aspx
Song of the Dodo: Island Biogeography State of the World’s Birds
in an Age of Extinction Report by Birdlife International using birds to
David Quammen assess the condition of global ecosystems.
(Simon & Schuster, 1997) www.birdlife.org/sowb2018
Vertebrate Life Edge of Existence
F. Harvey Pough and Christine M. Janis Listing the most threatened animals on Earth,
(Oxford University Press, 2018, 10th edn) taking into account both rarity and taxonomic
isolation, this is a sobering account of species
When Life Nearly Died: The Greatest
on the brink of extinction provided by the
Mass Extinction of All Time
Zoological Society of London.
Michael Benton
www.edgeofexistence.org/species/
(Thames & Hudson, 2015)
The Global Biodiversity Information Facility
Wilding: The Return of Nature to
An astounding international network and
a British Farm
research database providing open access to
Isabella Tree
information about all types of life on Earth.
(Picador, 2019)
www.gbif.org
Wonderful Life: Burgess Shale and
the Nature of History
Stephen Jay Gould
(Vintage, 2000)

Resources g 155
 NOTES ON CONTRIBUTORS

EDITOR CONTRIBUTORS
Mark Fellowes has been passionate about James Barnett is a behavioural ecologist
wildlife since an early age, spending his based at McMaster University, Ontario,
formative years in the wilds of the west of Canada. He has an MSc and a PhD from the
Ireland surveying birds and bringing bits of University of Bristol, UK, and his postdoctoral
the countryside back home. He completed research includes the study of predator–prey
his BSc in zoology and a PhD in evolutionary interactions and the way animal colours
biology at Imperial College London. function, evolve and are perceived by
Following a brief post-doctoral stint at the different species.
NERC Centre for Population Biology at
Imperial, he joined Reading as a lecturer. Amanda Callaghan is Professor of
Since then he became Professor of Ecology, Invertebrate Zoology at the University of
and he is now Pro-Vice Chancellor at the Reading, UK, and Curator of the Cole Museum
University. Professor Fellowes has of Zoology located on the university’s
published several books and numerous campus. Her research interests include
papers in research journals. His current mosquito ecology, entomology and the effect
work focuses on interactions between of microplastics and ecotoxicology in
people and wildlife, with an emphasis on freshwater invertebrates. She is a Fellow of
urban ecosystems. He works on insects, the Royal Society of Biology, and the Royal
birds and mammals, with ongoing projects Entomological Society. A former Editor of
in Ghana, Nigeria, India, the USA and Brazil, Antenna, the bulletin of the RES, Professor
as well as in the UK. He undertakes a range Callaghan is also the author of numerous
of outreach work to engage the public and papers and articles for academic journals.
media in the importance of biodiversity
and was listed as one of the UK’s 100 most
influential men under the age of 40 by
Esquire magazine.

156 g Notes on Contributors

Peter Capainolo has had an interest in Neil Gostling is an evolutionary biologist and
natural history, particularly ornithology, a Senior Teaching Fellow at the University of
since boyhood. Birds of prey fascinated him, Southampton, UK. Originally from London, he
and he received one of the first falconry spent every opportunity of his childhood at
licences issued by New York State at the age the Natural History Museum, and watching
of 18. He studied zoology and practised David Attenborough documentaries. He
falconry under Professor Heinz Meng at the received a BSc (botany and zoology) and a
State University of New York at New Paltz. PhD (evolutionary developmental biology)
Currently he is Senior Scientific Assistant/ from the University of Reading, before moving
Senior Museum Specialist in the Division of to Bristol to study fossil embryos from China,
Vertebrate Zoology at the American Museum and the Cambrian period. His research has
of Natural History and an adjunct faculty looked at the evolution of some of the earliest
member in the Department of Biology at birds, dinosaurs and mammals. Neil runs the
The City College of the City University of MRes in evolution and annually leads a field
New York. Peter is the author of a book on course to the Galápagos. He regularly gives
birds of prey and has contributed to several talks to natural history and Café Sci groups on
books on ornithology in general. Darwin, evolution and biology.

Rebecca Thomas is an urban ecologist and

Senior Teaching Fellow at Royal Holloway,
University of London, UK. Her research
interests focus on the conservation biology
and ecology of birds and mammals, specifically
in how people’s decisions affect the ecology
of wild species. Dr Thomas is particularly
interested in how human activity affects
ecological interactions at a range of scales,
and especially in trying to uncover some of the
unexpected and unpredicted consequences
of our behaviour.

Notes on Contributors g 157

 INDEX

A Broecker, Wallace Smith 138 corals 36, 130 flatworms 40, 80

abiogenesis 70 Burden, William Douglas 62 Coues, Elliott 64 flight 84
abiosis 112 Bush, Katharine 44 Courtenay-Latimer, Marjorie 58 Fossey, Dian 96
Actinopterygii 58 bush meat 134, 144 crustaceans 46 fossils 20, 84
African wild-dogs 108 Butenandt, Adolf 94 Cuvier, Georges 38 frogs 60, 76, 78
Alex the African Grey 94 butterflies 82 cytotoxins 30, 70, 82
Allee effect 112, 118 bycatch 134 G
allogenic engineers 112, 130 Byrne, Katharine 150 D gastropods 48
altruism 88, 98 Darwin, Charles 7, 15, 18, 22, gastrulation 70, 74
amniotes 52 C 84, 130 Gates, Ruth 36
amphibians 60 Carson, Rachel Louise 142 Dawkins, Richard 122 Gause, Georgy
analogous characteristics 12, 22 cassava mealybugs 124 DDT 142 Frantsevich 118
annelids 44 cats 122 detritivores 30 Gegenbaur, Karl 40
anthozoa 30 cehalopods 48 deuterostomes 30 genes 16
Anthropocene, the 134 ‘central dogma’ 12, 16 dinosaurs 24, 62 genome duplication 13
ants 91, 98, 100, 126 cephalochordates 52, 56 disease vectors 134 geological time 13
aposematic coloration 112 chameleons 96 DNA 12, 16 germ layers 70
archaeocytes 30, 34 chelicera 30 dodos 26 Gessner, Conrad 7
Ardila-Robayo, María Cristina 60 chemoreceptor 30 gills 78
Aristotle 6 chimpanzees 92, 106 E Goodall, Jane 92
Artedi, Peter 58 chitin 30 ecdysis 31, 42 gorillas 106
Arthropods 46 choanocytes 12, 30, 34 ecdysozoa 31 Gould, John 64
Audubon, John 7 choanoflagellates 12, 20 echinoderms 38 Grant, Robert Edmond 34
autogenic engineers 112, 130 chordates 12, 52, 56 ecosphere 134 Griffin, Donald 72–3
chytrid fungus 124 ectoderm 70, 74 Grinnell, Joseph 66
B clades 12 ectoparasites 112, 124 group living 100
bacterial symbionts 112, 120 Clark, Eugenie 54–5 elephants 148
bases 12 classical conditioning 92 endoderm 70, 74 H
Bateman, Angus John 106 climate change 138 endoparasites 31, 112, 124 habitat loss 140
bats 73, 84, 98 clitellum 30 endostyles 52, 56 Haeckel, Ernst 38
bees 92, 100 cloacal respiration 78 energetics 112 haemotoxins 70, 82
Beneden, Pierre-Joseph van 126 Cnidaria 36 eukaryotic organisms 12, 22 Hairston, Nelson, Sr. 120
Benton, Michael 24 Cobb, Nathan Augustus 42 eusocial behaviour 31, 33, 100 Haldane, J. B. S. 74
bilaterians 12, 30 coelom 30 evolution 18, 74 Hamilton, William D. 108
binomial nomenclature 52 coevolution 112 extinction 24 Harvey, William 78
bioaccumulation 134 commensal species 112 eyesight 80 al-Haytham, Hasan Ibn 80
biogeography 116 communication 94 Hemichordates 56
bioindicators 52 competition 118 F Hennig, Willi 22
biomass 30 competitive exclusion principle facultative relationships 112–13 herbivory 120
biosynthesis 30 112, 118 Finlay, Carlos 124 herpetologists 52
biotic homogenization 134, 146 cones 70, 80 first animals 20 heterotrophs 13
birds 64, 84, 138 conflict 96 fish 52, 58, 144 Hoekstra, Danielle ‘Hopi’
bombykol 88, 94 conodonts 12 Fisher, Ronald 108 Elizabeth 66
Brazil, Vital 82 convergent evolution 12 Fitzroy River turtles 78 Holland, Peter 56
breathing 78 coprolite 30 flagella 13 Hölldobler, Bert 100

158 g Index
homologous characteristics maximum sustainable yields polychaeta 31 totipotent cells 31, 34
13, 22 134, 144 predation 122 toxins 82
Hox genes 16, 52, 56 May, Robert 114–15 primary productivity 113 tracheal systems 78
human-wildlife conflict 148 Merian, Maria Sibylla 76 tragedy of the commons 135
Hutchinson, George Evelyn 116 mesoderm 70, 74 R transcription 13
Huxley, Thomas Henry 84 mesoglea 31, 36 radulae 48 translation 13
hydrozoa 31, 36 metamorphosis 76 red-necked phalarope 102 trematodes 40
molluscs 48 reproductive isolation 135 Trivers, Robert 98
I monophyletic group 13 reptiles 62 trophic cascades 113
ichthyology 52 monotremes 52, 113 rewilding 113, 128, 140 tuatara 53, 62
imaginal discs 70, 76 moths 82, 94 Rissler, Leslie Jane 62 tunicates 53
industrial melanism 13, 18 mutualisms 126 RNA 13
insects 46 rods 70, 80 U
inter/intraspecific competition 113 N Rothschild, Miriam 46 urban animals 150
invasive species 146 natural selection 18, 98, 104 roundworms 42 urochordates 53, 56
island species 26, 91, 116 nature deficit disorder 134 Rumphius, Georg Eberhard 48
nematodes 42 V
J neurotoxins 70, 82 S vector species 113
jellyfish 36 Nice, Margaret Morse 64 Sarcopterygii 58 venoms 82
Jones, Clive G. 130 Nichols, Richard 150 Say, Thomas 48 Villepreux-Power, Jeanne 48
notochords 52, 56 scramble competition 113
K sea anemones 36 W
K-T ME 13, 24 O sea cucumbers 38 Walcott, Charles Doolittle 20
keystone species 126, 128 Old Blue 102 sea stars 38 Wallace, Alfred Russel 14–15
kin selection 31, 88, 98 operant conditioning 88, 92 sea urchins 38, 120 Wallace’s Line 113, 116
Kizirian, David 60 opsins 71, 80 secondary metabolites 31 West-Eberhard, Mary Jane 32–3
Komodo dragons 62 organizers 70, 74 segmented worms 44 whales 66, 80
Krebs, John Richard 122 organogenesis 71, 74 sex allocation 108 Wilson, E. O. 90–1
Osteichthyes 58 sexual dimorphism 88, 104 Wright, Patricia 136–7
L over-harvesting 144 sexual selection 104
Laveran, Alphonse 124 Shachak, Moshe 130 Y
Lawton, Sir John 130 P sharks 55, 58 Youyou, Tu 124
learning 92 Paine, Bob 128 Slobodkin, Lawrence 120
lemurs 137, 140 parasitism 124 Smith, Frederick 120 Z
life-dinner principle 122 parasitoids 113, 124 snails 48, 102 Zahavi, Amotz 104
Linnaeus, Carl 7, 22 Pavlov, Ivan 92 snakes 62, 146 zoonoses 113, 124
Lophotrochozoa 31 Pepperberg, Dr Irene 94 speciation 113, 150
lungs 78 phenological asynchrony 134–5, sperm competition 106
138 sponges 34
M phenotypic plasticity 33 synapsids 53, 66
mammals 66 pheromones 88, 94
Mangold, Hilde 74 photobacteria 53 T
marsupials 66 placoid scales 53 tapeworms 40
mass extinctions (MEs) 24 planarians 40 teleosts 13
mating 102 pollution 142 tetrapodomorphs 53

Index g 159
 ACKNOWLEDGEMENTS

The publisher would like to thank the following for permission to Internet Archive/Open Knowledge Commons and Harvard Medical
reproduce copyright material on the following pages: School: 75; Kunstformen der Natur / Padent~commonswiki: 85;
Internet Archive/Book Images: 21; James St. John: 21; Library of
All images that appear in the montages are from Shutterstock, Inc. Tasmania: 25;Minneapolis Institute of the Arts: 99; NOAA: 37; Nobu
unless stated. Tamura: 25; PLOS: 90; Proceedings of the Zoological Society of
London: 151; Rhino Resource Center/Hermann Schlegel: 127; Siga: 47;
Donald Griffin image used courtesy of the Rockefeller Archive Center. Smithsonian Institution Archives: 21; Southeby’s: 67; Wellcome Images:
75; художник: 14.
Mary Jane West Eberhard image used with kind permission of Mary
Jane West Eberhard.
All reasonable efforts have been made to trace copyright holders and
Alamy/ 19th era 2: 39, 83; Age Fotostock: 41; Andrey Nekrasov: 57; Ann to obtain their permission for the use of copyright material. The
and Steve Toon: 95; Antiqua Print Gallery: 79, 139; Anton Sorokin: 125; publisher apologizes for any errors or omissions in the list above and
Archivist: 103; Arterra Picture Library: 145; Bazzano Photography: 83; will gratefully incorporate any corrections in future reprints if notified.
blickwinkel: 79, 139; Bookworm Classics: 43; BSIP SA: 41; Everett
Collection Inc: 143; Florlleglus: 23, 79, 119; FLPA: 45; Gaertner: 129;
gameover: 41, 109; Geerati Nilkaew: 99; Glasshouse Images: 123; Henri
Koskinen: 41; Historic Collection: 67, 77, 125; Historic Images: 77; Image
BROKER: 139; INTERFOTO: 39; Joel Sartore: 147; Kiyoshi Takahase
Segundo: 17; Library Book Collection: 41, 45, 57, 79; Mark Conlin: 145;
Maxim Tatarinov: 127; Michael Rhys Williams: 37; Narelle Power: 147;
Natural History Museum: 19, 57; Nature Photographers Ltd: 45, 57;
Nikolay Staykov: 77; nobleIMAGES: 149; Old Images: 17, 103; Oldtime:
109; Opera Nicolae: 19; Patrick Guenette: 17; Petr Pavluvcik: 119; RGB
Ventures/SuperStock: 147; Richard Mittleman/Gon2Foto: 129; Rob
Cousins: 115; Science History Images: 23, 57, 75, 147, 151; Steve Taylor
ARPS: 149; Stuart Donaldson: 47; The Book Worm: 57; The History
Collection: 99; Tot Collection: 125; WaterFrame: 45; WILDLIFE GmbH:
123; World History Archive: 27; www.pqpictures.co.uk: 43.

Biodiversity Heritage Library: 41, 67, 100, 103.

Boston Public Library: 19.

Flickr/ British Library: 67; Biodiversity Heritage Library: 99.

Getty/ Mike Windle: 137; Nnehring: 43, 45; ZU_09: 43.

Internet Archive/ Biodiversity Heritage Library: 25, 97, 105, 117;

Smithsonian Libraries: 85.

Wikimedia Commons/ Audubon: 131; Biodiversity Heritage Library: 45,

67; Bonhams: 105; British Library/Flickr Commons: 131; Bstelnitz: 55;
Colour Illustration by Mrs. Sarah L. Martin / University of Texas at
Austin, School of Biological Sciences: 107; E.J. Spitta: 47; Esculapio:
127; Internet Archive: 67, 107; Internet Archive/NCSU Libraries: 47;

160 g Acknowledgements