Reptiles, a various team of air-breathing vertebrates, are characterised by their scaly pores and skin, amniotic eggs, and ectothermic (chilly-blooded) metabolism. They're customarily labeled into 4 living orders: Crocodilia (crocodiles and alligators), Sphenodontia (tuataras), Squamata (lizards and snakes), and Testudines (turtles and tortoises).