Mole-Limbed Wormlizards: Bipedidae

The three species of mole-limbed wormlizards in this family are sometimes confused with earthworms, but they have scales and front legs. They are one of four families that fall into the group known as wormlizards or amphisbaenians (am-fizz-BAY-nee-ens). In all amphisbaenians, small rectangular scales form circular rings around their long thin bodies. A worm has rings around its body, too, but it has no scales and lacks most of the other features of wormlizards. Mole-limbed wormlizards, like other amphisbaenians, have one large tooth in the middle of the upper jaw, a thick and strong skull, small and sometimes invisible eyes, and a forked tongue. They do not, however, have ear holes or eyelids, like most lizards do. The mole-limbed wormlizards are different from other wormlizards, because they have a pair of small but strong front legs right behind the short rounded head. In addition, one of their clawed fingers has an extra bony piece, compared to the fingers of other reptiles. Mole-limbed wormlizards use their strong front legs, and probably this extra finger bone, to help them dig. Some scientists believe that, because the mole-limbed wormlizards have front legs, they are probably the most primitive of all the amphisbaenians. Other scientists disagree. These questions will no doubt continue, since no one has yet found a single fossil of any member of this family. Although mole-limbed wormlizards do not have hind legs, the skeleton still has some bits of hip bone and a tiny nub of thigh bone.

Mole-limbed wormlizards grow to 4.5 to 9.4 inches (11.5 to 24 centimeters) long and at the middle of the body are about 0.27 to 0.39 inches (7 to 10 millimeters) across. Only one-tenth to one-fifth of the body length is tail. The body is very bland-looking with no pattern and is colored pale pink, sometimes with a slightly orange tint. Individuals occasionally have a whiter belly. This animal sheds its skin (actually just the outer layer of skin) once in a while. When it sheds, the skin layer comes off in a single piece, just like it does in most snakes.