Reptiles, a various team of air-respiratory vertebrates, are characterised by their scaly skin, amniotic eggs, and ectothermic (chilly-blooded) metabolism. They can be ordinarily classified into 4 residing orders: Crocodilia (crocodiles and alligators), Sphenodontia (tuataras), Squamata (lizards and snakes), and Testudines (turtles and tortoises).