Adult frogs use their powerful hind legs to hop. The apodans are legless and nearly blind and resemble earthworms. Class Reptilia Reptiles have several adaptations for terrestrial living not generally found in amphibians. Scales containing the protein keratin waterproof the skin of a reptile, helping prevent dehydration in dry air. Because they cannot breathe through their dry skin, most reptiles obtain all their oxygen with lungs.
Many turtles also use the moist surfaces of their cloaca for gas exchange.
Most reptiles lay shelled amniotic eggs on land. Order Chelonia - the turtles. Amniotic eggs and scales on the legs are two reptilian features, but birds have feathers. Flight is typical of birds, but there are several flightless species, including the ostrich, kiwi, and emu. Flightless birds are collectively called ratites because their breastbone lacks a keel and the large breast muscles that attach to it in flying birds.