Adapting the cause of reptiles for survival on land.

Reptiles do not regulate body temperature, like warm-blooded mammals. Reptiles are ectothermic, often referred to as cold-blooded. Rather than relying on internal body temperature such as mammals or ambient water temperature, like many amphibians, reptiles use behavior and environment to maintain body temperature at optimal power. When they feel cold or sluggish, they bask in the sun to warm their bodies. When it gets too hot, they move into the shade or hide in underground burrows to avoid the heat.