Classification Of Animals

jellyfish

bath sponge

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

sea anemone

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

flatworm

elephant Invertebrates Many animals have either no skeleton at all, or they have a liver fluke shell or some other hard covering on the outside of their bodies. For example, nematode 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, lugworm and worms are all invertebrates.

rat swallow human

ostrich

snake crocodile

spider snail

frog

earthworm

newt starfish 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. 150

catfish

sea urchin

octopus

surgeon fish crab shark

butterfly millipede 151