Reptiles, a diverse team of air-respiratory vertebrates, are characterized by their scaly skin, amniotic eggs, and ectothermic (chilly-blooded) metabolism. They're traditionally categorised into 4 residing orders: Crocodilia (crocodiles and alligators), Sphenodontia (tuataras), Squamata (lizards and snakes), and Testudines (turtles and tortoises).