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spider

crab

millipede

butterfly

starfish

sea urchin octopus

snail earthworm

jellyfish

seaanemone

bath sponge

flatworm

liver fluke

Invertebrates

Many animals have either no

skeleton at all, or they have a

shell or some other hard

covering on the outside of

their bodies. For example,

earthworms and jellyfish

have no skeleton at all, and

crabs and insects have a shell

or some other tough outer

covering, or external skeleton.

These animals, either with an

external skeleton or with no

skeleton at all, are called

invertebrates. Spiders, insects,

and worms are all

invertebrates.

nematode

lugworm

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human

elephant

rat

swallow

ostrich

snake

crocodile

frog

newt

surgeon fish

shark

catfish

Vertebrates

Some animals have a skeleton inside their

bodies. Part of this skeleton is a backbone.

These animals, with a backbone and internal

skeleton, are called vertebrates. The vertebrates

are broken down into five smaller groups, called

mammals, birds, reptiles, amphibians, and fish.

Classification of Animals Unlike plants, animals cannot make their own food. They have toeat other living things to survive. The animal kingdom can bedivided into vertebrates and invertebrates. Vertebrates are animalsthat have backbones, such as fish, reptiles, and mammals.Invertebrates are animals that do not have backbones.

Vertebrates are all more closely related to each other than to otheranimals, so they are a proper scientific grouping. However,invertebrates are not a proper scientific grouping because thedifferent types of invertebrate are not closely related to each other.