Explains the things, such as feathers and beaks, that define birds as birds, using a herring gull as an example.

Explains the physical characteristics, such as scales and lungs, that define reptiles as reptiles, using alligators as an example.

Fish are one group of animals. There are more than 20,000 kinds, or species, of fish. Seahorses, manta rays and eels are fish. So are rainbow trout. These anima

Describes the physical characteristics of tigers, habitat, food, reproduction and more to show why it's a mammal.

Amphibians are one group of animals. There are about 4200 species, or kinds, of amphibians. Frogs, salamanders, newts and toads are amphibians. But lizards, ott