A reptile walk is similar to a mammalian walk in that the front and back legs move in opposition. The reptile's low center of gravity, however, forces the body to work more. As it walks, a reptile bends its torso into a curve to help push the feet along (see Figure 2). Despite this awkward motion, some reptiles are capable of moderate speeds. Crocodilians raise their bodies off the ground and make short, fast rushes.
Short-bodied lizards also can move quickly for short distancesin fact, some lizards can lift their front legs off the ground when running. Longer-bodied lizards have greater difficulty in raising their bodies because they have short legs. This forces their bodies to move more like snakes. In fact, the reptiles with the shortest legs actually have no legs allthese are called snakes.
Figure 2 In a reptile walk, the animal's low center of gravity forces the spine and torso to bend much more than in a mammal.