Reptile by Circe Denyer. Click here for original.
Class Reptilia
Class reptilia includes the turtles, lizards, snakes, crocodiles/alligators, and relatives. Reptiles have protective scales covering their body, a shell around their eggs, and are ectothermic (body temperature varies with environment) with three-chambered hearts and four in crocodiles and alligators. There is controversy that birds are just feathered reptiles, and thus, should be in the same class instead of a separate one.