To survive on land, the reptiles had to develop a skin relatively impermeable to water, so as to prevent desiccation, and hence not well suited for respiration. Thus, while a few specialized reptiles (for example, sea snakes) can acquire nearly half of their oxygen supply through their skin, most reptiles depend almost entirely on the lungs for gas exchange. Reptilian lungs are considerably more complex than those of amphibians, showing much more internal partitioning to provide additional surface area for gas exchange between lung gas and blood. The most complex reptilian lungs are found in sea turtles such as ...