While hunting for food, reptiles, especially snakes develop an incredible sense of smell. They use their tongue to sense the chemicals in the air which tell them how near their prey is, there are some snakes that detect the body heat of their prey and this ability is built inside them. The two most important components in the catching of the prey are constriction and venom. Since snakes are cold-blooded reptiles they need to keep their body warm in order to stay alive and therefore to choose the right environmental conditions in which their body is kept warm. Often snakes allow sunlight to help keep their body warm however they still need to cool off and therefore hide in some dark places.