Classification - The Science Site

There are so many species of organisms we need to have some means of grouping them.
In about 1750 Carolus Linnaeus, a Swedish naturalist, devised a system of grouping organisms into categories based on characteristics, such as shape or structure.

It is his system we use today

The major classification levels
from largest group to smallest

Kingdom – Phylum -Class – Order – Family – Genus- Species

Each kingdom is divided into several smaller groups called Phyla.
Each phylum is divided into still smaller groups called classes.
Each class into several orders and so on

There are 5 major kingdoms:

Bacteria
Single celled animals
Fungi
Plants
Animals

The animal kingdom is divided into several smaller groups called Phyla.
The two phyla you need to know are: Phylum Chordata – The VERTEBRATES (which have an internal skeleton)
and the Phylum of Arthropods which all have jointed legs and a hard outside skeleton called an exoskeleton

VERTEBRATES Animals that have an internal skeleton (Phylum Chordata) These animals all have a backbone
Group	Main features	Examples
Class Mammals	Have hair or fur on their body Babies are born alive and are fed with milk by their mother. Breath with lungs Warm Blooded	Dog, Mouse, Whale, Human
Class Birds	Have feathers Lay eggs with hard shells Breath with lungs Warm Blooded	Eagle, Robin, Crow
Class Reptiles	Skin covered in scales. Lay soft-shelled eggs on land Breath with lungs Cold blooded	Snake, Lizard, Turtle, Tortoise
Class Amphibians	Have a smooth skin. The young are born with gills and live underwater but the adults have lungs and often live on land. They lay jelly-covered eggs under water. Cold blooded	Frog, Toad, Newt
Class Fish	Have fins and scales Lay eggs in water Breath with gills Cold blooded	Minnow, Shark, Cod

INVERTEBRATES Animals that have no backbone
Arthropods (Phylum Arthropoda) These animals all have jointed legs and an exoskeleton (An exoskeleton is a hard, outside skin)
Animal group	Main features	Examples
Class Insects	3 pairs of legs, 3 parts to their body, hard outside skin	Fly, Butterfly, Ladybird, Ant
Class Arachnids	4 pairs of legs and 2 parts to their body	Spider, Scorpion
Class Crustaceans	More than 8 legs but less than 20. Often have a very hard, jointed skin	Crab, Lobster, shrimp
Other invertebrates
Phylum Mollusca Molluscs	Have a soft body and a muscular foot. Sometimes they have a hard shell.	Slug, Snail, Octopus
Phylum Annelida Annelids	Have a long, thin body which is divided into little segments.	Earthworm, Leach

*A warm blooded animal keeps its body at a constant temperature
eg humans have a body temperature of 37 C
A cold blooded animal has a body whose temperature varies according to the conditions.
eg The temperature of a fish would be slightly above that of the surrounding water (more if it had just been swimming rapidly)
Only birds and mammals are warm-blooded. all other animals are cold-blooded

Classification of the The Plant Kingdom

1.Flowering plants: produce SEEDS. Eg grass, apple, oak, rose

All other plants are NON-FLOWERING and do NOT produce seeds. Eg algae, moss and fungi.

2. Algae
Single celled plants.
Reproduce asexually by binary fission.
Live in wet places. Have no leaves or roots.

3. Moss
Reproduces asexually by making spores. Live in damp, shady places.

4. Ferns and Horsetails
Plants that have a tough fibrous stem and grow from a rhizome just under the surface of the soil . Reproduce by making spores

Fungi
Fungi are not true plants as they do not possess green chlorophyll so cannot carry out photosynthesis.

They take their food from the material they are growing on/in.
Reproduce asexually by making spores.
Examples of different fungi: mushroom, yeast, mould.

Fungi (along with bacteria) are very important in the food chain for the recycling of nutrients in the soil.

Some fungi are harmful and can cause disease in crops (eg potato blight).

Some fungi are useful to man eg yeast which is used to ferment sugar and produce alcohol in the brewing industry.

Words to know from this section
VERTEBRATE Has an internal skeleton

INVERTEBRATE Has no internal skeleton

EXOSKELETON An external skeleton, like a hard skin.

WARM-BLOODED Animals whose body temperature is constant are called warm-blooded. eg Human: body temperature 37^oC.

COLD-BLOODED Animals whose body temperature alters with the temperature of the surroundings eg fish