Reptiles, a various group of air-respiration vertebrates, are characterised by their scaly pores and skin, amniotic eggs, and ectothermic (cold-blooded) metabolism. They can be traditionally categorised into four living orders: Crocodilia (crocodiles and alligators), Sphenodontia (tuataras), more info Squamata (lizards and snakes), and Testudines (