Diversity in

Living
Organisms
Shiva Class 9-B
Diversity In Living Organisms
Diversity in living organisms refers to the wide range of species that exist
in the natural world, encompassing various forms of life such as
microorganisms, plants, animals, and fungi.
Studying diversity is essential as it helps understand the variety of life
forms on Earth. It teaches about the interconnectedness of organisms
within ecosystems.
Recognizing diversity fosters conservation awareness and promotes
environmental stewardship.
Understanding diverse species aids in agricultural practices and medical
research.
Appreciating biodiversity enriches cultural connections to nature and
supports sustainable development efforts.Instructions for use.
Taxonomy
Taxonomy is defined as the science of classification
of living organisms based on similarities and
differences in their characteristics. It involves
categorizing organisms into groups or taxa to
organize and understand the vast diversity of life
on Earth.

Carolus Linnaeus is recognized for his significant

contributions to the classification of living
organisms. His major contributions include:
1. Development of Binomial Nomenclature
2. Establishment of Hierarchical Classification
3. Publication of "Systema Naturae": Linnaeus
published "Systema Naturae" in 1735, which laid
the foundation for modern taxonomy
The Hierarchy of Classification
Groups :-
Biologists, such as Ernst Haeckel (1894), Robert
Whittaker (1969) and Carl Woese (1977) have
tried to classify all living organisms into broad
categories, called kingdoms. The classification
Whittaker proposed has five kingdoms: Monera,
Protista, Fungi, Plantae and Animalia, and is
widely used.
 Further classification is done by naming the
sub-groups at various levels as given in the
following scheme:

6.Phylum/ Division
5.Class
4.Order
3.Family
2.Genus
1. Species
The important characteristics of the five
kingdoms of Whittaker are as follows:

● Monera

Monera are defined as a group of unicellular

organisms characterized by prokaryotic cell
structure. They lack a nucleus and membrane-
bound organelles. Monera include bacteria and
blue-green algae (cyanobacteria). They play crucial
roles in nutrient cycling, decomposition, and
symbiotic relationships.
• Protista

Protista are defined as a diverse group of mostly

unicellular eukaryotic organisms. They exhibit
various modes of nutrition and locomotion. Protists
include protozoans, algae, and slime molds,
inhabiting diverse aquatic and terrestrial
environments. They play vital ecological roles as
primary producers and consumers in ecosystems.
Plantae

Plantae are defined as a kingdom of multicellular,

eukaryotic organisms characterized by autotrophic
nutrition. They possess cell walls made of cellulose
and chloroplasts for photosynthesis. Plantae
encompass a wide variety of species, including
mosses, ferns, gymnosperms, and angiosperms,
contributing to oxygen production, food webs, and
ecosystem stability.
Thallopytha

Plants that do not have well-differentiated body

design fall in this group. The plants in this group are
commonly called algae. These plants 2020-21 86
SCIENCE are predominantly aquatic. Examples are
Spirogyra, Ulothrix, Cladophora, Ulva and Chara.
BRYOPHYTA

These are called the amphibians of the plant

kingdom. The plant body is commonly
differentiated to form stem and leaf-like structures.
However, there is no specialised tissue for the
conduction of water and other substances from one
part of the plant body to another. Examples are
moss (Funaria) and Marchantia
PTERIDOPHYTA

In this group, the plant body is differentiated into

roots, stem and leaves and has specialised tissue for
the conduction of water and other substances from
one part of the plant body to another. Some
examples are Marsilea, ferns and horse-tails
ANGIOSPERMS

These are also called flowering plants. The seeds

develop inside an ovary which is modified to
become a fruit. Plant embryos in seeds have
structures called cotyledons. Cotyledons are called
‘seed leaves’ because in many instances they
emerge and become green when the seed
germinates. The angiosperms are divided into two
groups on the basis of the number of cotyledons
present in the seed. Plants with seeds having a
single cotyledon are called monocotyledonous or
monocots. Plants with seeds having two cotyledons
are called dicots.
GYMNOSPERMS

This term is derived from two Greek words: gymno–

means naked and sperma– means seed. The plants
of this group bear naked seeds and are usually
perennial, evergreen and woody. Examples are
pines and deodar
Fungi

These are heterotrophic eukaryotic organisms.

Some of them use decaying organic material as food
and are therefore called saprotrophs. Others
require a living protoplasm of a host organism for
food. They are called parasites. Many of them have
the capacity to become multicellular organisms at
certain stages in their lives. They have cellwalls
made of a tough complex sugar called chitin.
Examples are yeasts, molds and mushrooms.
Animalia

Animalia is defined as a kingdom comprising

multicellular, eukaryotic organisms characterized
by heterotrophic nutrition. They lack cell walls and
typically exhibit mobility at some stage of their life
cycle. Animalia encompasses a wide diversity of
species, including invertebrates and vertebrates,
playing various ecological roles in ecosystems.
PORIFERA

The word Porifera means organisms with holes.

These are non-motile animals attached to some
solid support. There are holes or ‘pores’, all over the
body. These lead to a canal system that helps in
circulating water throughout the body to bring in
food and oxygen. These animals are covered with a
hard outside layer or skeleton. The body design
involves very minimal differentiation and division
into tissues. They are commonly called sponges, and
are mainly found in marine habitats.
COELENTERATA (CNIDARIA)

These are animals living in water. They show more

body design differentiation. There is a cavity in the
body. The body is made of two layers of cells: one
makes up cells on the outside of the body, and the
other makes the inner lining of the body. Some of
these species live in colonies (corals), while others
have a solitary like–span (Hydra). Jellyfish and sea
anemones are common examples.
PLATYHELMINTHES

The body of animals in this group is far more complexly designed than in the two other groups we
have considered so far. The body is bilaterally symmetrical, meaning that the left and the right
halves of the body have the same design. There are three layers of cells from which differentiated
tissues can be made, which is why such animals are called triploblastic. This allows outside and
inside body linings as well as some organs to be made. There is thus some

degree of tissue formation. However, there is no true internal body

cavity or coelom, in which well developed organs can be

accommodated. The body is flattened dorsoventrally

(meaning from top to bottom), which is why these animals

are called flatworms. They are either free-living or parasitic.

Some examples are free-living animals like planarians, or parasitic

animals like liverflukes.

NEMATODA

The nematode body is also bilaterally symmetrical

and triploblastic. However, the body is cylindrical
rather than flattened. There are tissues, but no real
organs, although a sort of body cavity or a
pseudocoelom, is present. These are very familiar as
parasitic worms causing diseases, such as the
worms causing elephantiasis (filarial worms) or the
worms in the intestines (roundworm or pinworms)
ANNELIDA

Annelid animals are also bilaterally symmetrical

and triploblastic, but in addition they have a true
body cavity. This allows true organs to be packaged
in the body structure. There is, thus, extensive
organ differentiation. This differentiation occurs in
a segmental fashion, with the segments lined up one
after the other from head to tail. These animals are
found in a variety of habitats– fresh water, marine
water as well as land. Earthworms and leeches are
familiar examples.
ARTHROPODA

This is probably the largest group of

animals. These animals are bilaterally

symmetrical and segmented. There is

an open circulatory system, and so the

blood does not flow in welldefined blood

vessels. The coelomic cavity is

blood-filled. They have jointed legs (the

word ‘arthropod’ means ‘jointed legs’).

Some familiar examples are prawns,

butterflies, houseflies, spiders, scorpions and crabs.

MOLLUSCA

In the animals of this group, there is bilateral

symmetry. The coelomic cavity is reduced. There is
little segmentation. They have an open circulatory
system and kidney-like organs for excretion. There
is a foot that is used for moving around. Examples
are snails and mussels
PROTOCHORDATA

These animals are bilaterally symmetrical,

triploblastic and have a coelom. In addition,

they show a new feature of body design, namely

a notochord, at least at some stages during their

lives. The notochord is a long rod-like support

structure (chord=string) that runs along the back

of the animal separating the nervous tissue from

the gut. It provides a place for muscles to attach

for ease of movement. Protochordates may not have

a proper notochord present at all stages in their lives or for the entire length of the animal.

Protochordates are marine animals. Examples are Balanoglossus, Herdmania and Amphioxus.
VERTEBRATA

These animals have a true vertebral column and internal skeleton, allowing a completely different
distribution of muscle attachment points to be used for movement. Vertebrates are bilaterally
symmetrical, triploblastic, coelomic and segmented, with complex differentiation of body tissues and
organs. All chordates possess the following features:

(i) have a notochord

(ii) have a dorsal nerve cord

(iii) are triploblastic

(iv) have paired gill pouches

(v) are coelomate.

CYCLOSTOMATA

Cyclostomes are jawless

vertebrates. They are

characterised by having

an elongated eel-like

body, circular mouth , slimy skin and are scaleless. They are ectoparasites or borers of other
vertebrates. Petromyzon (Lamprey) and Myxine (Hagfish) are examples.
PISCES

These are fish. They are exclusively aquatic animals. Their skin is covered with scales/ plates. They
obtain oxygen dissolved in water by using gills. The body is streamlined, and a muscular tail is used for
movement. They are cold-blooded and their hearts have only two chambers, unlike the four that
humans have. They lay eggs. We can think of many kinds of fish, some with skeletons made entirely of
cartilage, such as sharks, and some with a skeleton made of both bone and cartilage, such as tuna or
rohu.
AMPHIBIA

These animals differ from the fish in the lack of scales, in having mucus glands in the skin, and a three-
chambered heart. Respiration is through either gills or lungs. They lay eggs. These animals are found
both in water and on land. Frogs, toads and salamanders are some examples.
REPTILIA

These animals are cold-blooded, have scales and breathe through lungs. While most of them have a
three-chambered heart, crocodiles have four heart chambers. They lay eggs with tough coverings and
do not need to lay their eggs in water, unlike amphibians. Snakes, turtles, lizards and crocodiles fall in
this category.
AVES

These are warm-blooded animals and have a four-chambered heart. They lay eggs. There is an outside
covering of feathers, and two forelimbs are modified for flight. They breathe through lungs. All birds fall
in this category.
Mammals

Mammals are warm-blooded animals with

four-chambered hearts. They have mammary

glands for the production of milk to nourish

their young. Their skin has hairs as well as

sweat and oil glands. Most mammals familiar

to us produce live young ones. However, a f

ew of them, like the platypus and the echidna

lay eggs, and some, like kangaroos give birth

to very poorly developed young ones.

Nomenclature

Nomenclature refers to the system of assigning names to living organisms

based on standardized conventions. It involves the use of binomial nomenclature,

where each organism is given a unique two-part Latin name consisting of its genus

and species. This naming system, introduced by Carl Linnaeus, aids in clear

communication and organization within the scientific community.

Nomenclature provides a universal language for identifying and classifying

organisms, facilitating the study of biodiversity and evolution.

It plays a crucial role in taxonomy,

the science of classifying and categorizing living organisms.