Animal groups
To make it easier to study animals, scientists have arranged them into
groups. All the animals in each group are alike in one or more important
ways.
Mammals
If an animal drinks milk when it’s a baby and has hair on its body, it
belongs to the group called mammals.
Reptiles
If an animal has a scaly skin, is cold-blooded, and is always born on
land, it belongs to the group called reptiles.
Amphibians
If an animal has a skeleton, is born in water and breathes with gills,
but can live on land when it is grown up, it belongs to the group called
amphibians.
Birds
If an animal comes out of an egg with a hard shell and has feathers on
its body when it grows up, it belongs to the group called birds.
Fish
If an animal lives in water and has gills and also has scales and fins
on its body, it belongs to the group called fish.
Arthropods
If an animal has three or more pairs of jointed legs, a hard covering
over its whole body, and no skeleton, it belongs to the group called
arthropods.
Mollusks
If an animal has a soft body with no skeleton, but is normally protected
by a hard shell, it belongs to the group called mollusks.
