Animals are multicellular living organisms that grow, reproduce, are capable of movement, respire and give off wastes. They cannot make their own food, like plants.
Although some of the finer points of animal classification are still being disputed, children can benefit from learning that animals can be grouped together if they share enough characteristics. Animals are divided into two main groups: vertebrates (with internal backbones) and invertebrates (without internal backbones). The main divisions of vertebrates are fish, amphibians, reptiles, birds, and mammals.
Fish have fins and scales. They live in water whether fresh or salty and breathe oxygen through their gills.
Reptiles are air breathing that have internal fertilization and scaly bodies. Reptiles include snakes, lizards, crocodiles, alligators, and turtles. Amphibians have smooth, moist skin and breathe through lungs as adults. When they are young, they breathe through gills.
Amphibians must lay eggs in water and must keep their skin moist at all times.
Birds have feathers. Their front limbs are modified to form wings and their eggs are protected by a shell.
Mammals have fur or hair. Mammals usually have young that develop in the mother's body. The only exceptions to these generalities are the platypus and spiny anteater which lay eggs. Mammals all have glands in the mother's body that produce milk for their young.
