Reptiles raise their body temperatures by lying out in a warm place, this is called basking. They seek out a sunny spot and lie there until their bodies have warmed up enough for them to search for prey. This process is called thermoregulation. If they cannot get warm enough, they cannot digest food so they will not hunt. Some lizards and snakes can flatten themselves to expose more of their skin surface to the sun, heating up more quickly. Such cold-blooded animals are known as ecototherms; warm-blooded animals like mammals are endotherms.