Wormlizards: Amphisbaenidae

The members of this family, known simply as wormlizards, are long, thin, legless animals. Their scales are arranged in rings around the body with each ring separated from the next by a shallow groove. This ring and groove pattern makes them look much like earthworms, even though the worms lack scales. In some species of wormlizard, the head is round. In others, it may be shaped like a shovel, or in some cases the snout may come to a point. They have no openings for their ears, as the lizards do, and they have only the smallest of eyes showing below a see-through scale, if they are visible at all. They have no legs, but all species in this family have tiny bits of hip bones inside their bodies. They do not, however, have a sternum (STER-num), which is the bone at the front of the chest that in most animal species connects to the ribs.

Most wormlizards reach about 10 to 16 inches (25 to 40 centimeters) long as adults, but some species are much smaller or much larger. The smallest species lives in Africa and only grows to 4 inches (10 centimeters) long, while the largest, known as the white-bellied wormlizard, can reach more than 32 inches (80 centimeters). A wormlizard's tail, which can look much like the rest of the body, actually starts at the vent, a slit-like opening on the underside of the animal. The tails in these animals are very short, usually less than one-tenth of the overall body length. The tails may be rounded, pointed at the end, or have a flattened shape. Many of the 160 species of wormlizards have about the same color: pale pink or pale orange-pink, sometimes with a whitish belly. Some species, however, are colored brown, yellow, purple, or gray, and a few even have eye-catching black-and-white patterns. The males and females of each species look alike.

The wormlizards in this family have many of the same features of three other families of animals: the mole-limbed wormlizards, the Florida wormlizards, and the spade-headed wormlizards. These four families all fall under the group called amphisbaenians (am-fizz-BAY-nee-ens). Like the wormlizards in this family, many of them look much like earthworms, and all except the mole-limbed wormlizards are legless. Interestingly, all wormlizards have only one lung, or one large lung and one tiny lung, and one larger tooth in the middle of the upper jaw. In those that have eyes, they have no eyelids. They also have a forked tongue and a thick, strong skull. They have an unusual hearing system that allows them to pick up even slight vibrations underground. In this system, a little structure attaches the ear to tissue on the side of the face. When they are slithering about, they can feel vibrations through the ground with the bottom of the face. The vibration then runs up the tissue and to the ear, which hears it. This ability, which lets the wormlizards hear even small movements made by other animals, comes in particularly handy when the wormlizards are looking for ants and other insects to eat.