Groups of Animals

Because there are so many different types of animals in the world biologists have sorted them into groups. This is called classifying. The two main groups of animals are vertebrates and invertebrates.

Vertebrates are all animals with a backbone. Humans have a backbone which is part of their skeleton. A skeleton gives the body support and shape.

Invertebrates are all animals without a backbone. These animals do not have a bony skeleton. All insects are invertebrates. They do have a skeleton but it is on the outside of their bodies and is not made of bone.

These two main groups have been divided into smaller groups. This is called sub-dividing the group.

We must be careful when we make a list of their differences. It is easy to say that all fish swim. The problem is that amphibians, such as the frog, also swim. Whales and dolphins swim and they are mammals. many insects swim. It is easy to think that 'all birds fly' but the ostrich and the penguin do not fly. On the other hand, there is a fish and there is a squirrel which can glide through the air! A lot of insects can fly. Biologists have to be very careful when they decide on reasons for putting animals into groups.

Vertebrate Groups
The images hyperlink to more information about each group.

	Fish
	Amphibians
	Reptiles
	Birds
	Mammals

Invertebrate Groups
The images hyperlink to more information about each group

	Jellyfish
	Molluscs
	Starfish
	Worms

• Arthropods

	Crustaceans
	Insects
	Myriapods
	Spiders

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© Paul Billiet and Shirley Burchill 2008