Two Legged Worm Lizards

Ajotles belong to the only genus (Bipes) of the amphisbaenian family Bipedidae. They live in Mexico and are about 18-24 cm (7-9.5 in) long. All of the pinkish, elongated, worm-like, cylindrical body has annulations of scales behind the head. The head is rounded and short with a rounded snout and no ear openings. There is no neck and no ear openings. The snout is rounded and the vestigal eyes are beneath a transluscent scale on either side of the head . No ear openings are present.

These carnivorous, burrowing reptiles differ from other worm lizards as they have have two stubby forelimbs placed just behind the head (1). They use the shovel-like limbs and well-developed claws to scrape away soil while they burrow through the soil, rather like a mole (2), but can place the limbs in recessed areas alongside the body. The expanded ulnar scales on the limbs help to move soil as the animal digs through substrate. The overhanging flesh just behind the point of insertion of the front limb lets the ajotle reduce its circumference while it moves through a tunnel (3). The tail is short and blunt and breaks off along fracture planes if it is grabbed by a predator. Ajotles cannot regenerate a lost tail.

Ajotles live beneath debris, litter, rocks and the roots of small shrubs and grasses.

Predators include snakes and large predaceous arthropods. When an ajotle is picked up, it energetically jumps and writhes like an earthworm, contorting its body to avoid the grip of a predator. It keeps its head hidden and releases a foul smelling musk from the cloaca (3).

There are four species.

Bipes is a genus of amphisbaenians found only in Mexico, the sole living member of the family Bipedidae. They are carnivorous, burrowing reptiles, but unlike other species of amphisbaenians, they possess two stubby forelimbs placed far forward on the body. They also retain an almost complete pectoral girdle. The shovel-like limbs are used to scrape away soil while burrowing, in a manner similar to a mole. Evidence for their occurrence in the United States is reviewed by Somma (1993).