Classification

Is the organisation of organisms into groups using anatomical, physiological features.

S – it is also possible to use biochemical methods such as DNA structure and the study of evolutionary
relationships (known as cladistics)

Organisms are collected into groups of decreasing size, the largest grouping is the Kingdom, followed by
Phylum, Class, Order, Genus and Species.

A species is a particular kind of organism that breeds successfully together – i.e. produces fertile
offspring. Individual organisms are named with the binomial system of nomenclature where each species
is given a generic (Rana) and a specific name (edulis). The genus is a very closely related group of
organisms; the species is an individual type of organism e.g. Rana edulis is the edible frog, Rana graeca
is the Greek frog, both are Green frogs but do not interbreed.

Three examples using the traditional system of classification are:

Group Examples
Human Greek (Stream) Frog Locust
Kingdom Animalae* Animalae Animalae
Phylum Chordata Chordata Arthropoda*
Class Vertebrata* Vertebrata Insecta*
Order Mammalia* Amphibia* Orthoptera
Genus Homo* Rana Locusta
Species sapiens graeca migratoria

Kingdoms:
Monera (Bacteria) are simple single-celled organisms without a true nucleus e.g. bacteria.
Protoctista are single celled but with a true nucleus.
S Fungi have a hyphal structure (threads), cell wall e.g. moulds and also can be single-celled e.g. yeasts
Plants (Plantae) are multicellular with cellulose cell walls and photosynthesise
Animals (Animalae) are multicellular with no cell walls, heterotrophic organisms with a nervous system.
S Viruses are not considered as living organisms because they themselves do not exhibit the
characteristics of living organisms. They do have genetic material and an outer protein coat and are able
to invade host cells and cause them to make new virus particles (this damages cells – hence the
pathogenic effect)

Phyla:
Chordata are animals with a dorsal nerve cord (a main nerve trunk in their back).
Arthropoda have an exoskeleton and jointed limbs

Classes:
Vertebrata have a backbone.
Insecta have compound eyes, 3 parts to the body, 3 pairs of walking legs, 2 pairs of wings and 1 pair of
antennae.

Orders:
Amphibia lay eggs without shells (so usually in water), have a larval stage (e.g. tadpole) and can
exchange gases through thin permeable skin.
Mammalia have external ears, hair and mammary glands.

Genus:
Homo has an upright stance, opposable thumb and fingers and a large brain.
Practical work (to be done in your exercise book)

1. The Phylum Arthropoda

contains 4 classes, use the specimens to complete the table below

Class Examples Number of Number of Eye type Antennae Other

pairs of body parts (simple or number feature
limbs compound)
Myriapod

Arachnid

Crustacea

Insecta

There are more species of insects than of all other animals combined - list some features observable on
the specimens that have helped insects to be so successful.

2. Make a drawing of each of the 5 classes of vertebrates. On each drawing, name the specimen, and
annotate the diagram with a) the classificatory features and b) the adaptations to its environment.
The 5 classes are Pisces, Amphibia, Reptilia, Aves and Mammalia

3. Flowering plants (Class Angiosperms) are plants that have a vascular system (phloem and xylem)
and produce flowers. They are further divided into Monocotyledons which have one cotyledon in the
seed, thin leaves with parallel veins e.g. rice and Dicotyledons which have two cotyledons in the seed,
broad leaves with net veins e.g. pea.
Using drawings and notes compare a) the seeds and b) the leaves of the two classes of the phylum
Angiosperms (flowering plants) - the Monocotyledons and the Dicotyledons. Use the labels on the
drawings to clearly illustrate the differences between the two groups.

4. Decide which organism of the three types of worm is a

Nematode Thread like structure with a distinct head and no segmentation
Annelid Metameric segments with projections, parapodia, for movement
Mollusc Single shell covers a muscular “foot” containing the body organs and mouth.
and draw each specimen to illustrate why you have placed them in that particular group

Each drawing must have a scale – the number or fraction given by the true size divided by the size of the
drawing.
Example – if the animal is 30mm long and your drawing is 18 mm, the magnification is 18/30 which
cancels to 9/15 or 0.6.

Classification Keys
Here is an example of a classification key done by a Maltese cardiologist who is a also a naturalist by
hobby.

Maltese Mammals by C. Savona-Ventura.

5. Use this key to place a dog, a rabbit, a goat, a bat, a dolphin, a mouse and a mole in their
correct Order in the sub-class of mammals.
Key to the Sub-class EURTHERIA (mammals with a placenta)
1a. - Posterior limbs absent or rudimentary. Caudal end of body transformed into a horizontal fin.
Aquatic.........................CETACEA
1b. - Posterior limbs present and used for progression. Caudal end of body not transformed in a fin.
Terrestrial or partially aquatic................2
2a. - Anterior limbs join with the posterior by a membrane which enables flight....CHIROPTERA
2b . - Anterior and posterior limbs are free and independent, used for progression on land, and more or
less transformed for aquatic purposes...........3
3a. - End of digit provided with a claw. Head never provided with horns...............4
3b. - End of digit provided with a hoof. Head sometimes provided with horns...............UNGULATA
4a. - Incomplete dentition. Canine absent. Greatly developed incisors, visible from outside and separated
from the remaining teeth by a diastema...........5
4b. - Complete dentition. Canine present, well developed or otherwise. Incisors not visible from
outside........................6
5a. - Two pairs of superior incisors...........LAGOMORPHA
5b. - One pair of superior incisors............RODENTIA
6a. - Teeth not very dissimilar with regards to form and size. Canines do not surpass considerably the
level of the other teeth (except in Talpa); medial incisors are more developed than the rest. Muzzle
pointed like a tube. Small size..........INSECTIVORA
6b. - Teeth different in form and size. Canines very developed, surpassing considerably the level of the
other teeth. Muzzel more or less elongated, but rounded at its end. Medium or large
size......................................CARNIVORA
http://www.geocities.com/RainForest/3096/mammals.html accessed May 2011.
 6. Use the key below to identify A, B, C, D, E and F and place them in the correct Order (O) of
the arthropods:

1).3 or 4 pairs of limbs go to 2

Many pairs of limbs go to 5

2).3 pairs of limbs, 1 pair of antennae go to 3

4 pairs of limbs, no antennae go to 4

3).Wingcase present, one pair of wings O. Coleoptera

Two pairs of wings, no wingcase O. Hymenoptera

4).Pincers present, long tail O.Scorpiones

No tail, spinneret O.Araneae

5) One pair of legs per body segment O. Chilopoda

Two pairs of legs per body segment O. Myriopoda

[Copy the dichotomous key and add in the common names of the specimens next to their orders (O)]