Snakes and lizards have a specialized, chemically sensitive organ, called Jacobson's organ, located in the roof of their mouths. These animals can detect the presence of chemicals in their surroundings by flicking their tongues out and in rapidly, pressing the tongue against the organ with each retraction. Heat-sensitive organs line the lips of some boas and pythons and are also located on the sides of the heads of pit vipers. Thus, because the pit vipers can sense infrared radiation, they can detect and strike their prey even in total darkness. How Snakes Move Locomotion.
Reptiles use various forms of locomotion to move from place to place.
Although most lizards walk on all fours, some use only their hind limbs when running. Some snakes and legless lizards move by attaching their belly scales to rough surfaces and pulling themselves forward. To help movement through the water, aquatic turtles have flippers or webbed feet and sea snakes are equipped with flattened tails. No modern reptile can fly, but certain tropical snakes and lizards have developed a means of flattening their bodies and gliding from tall trees. There were once about 16 orders in this class.