Amphisbaenia (called
amphisbaenians or
worm lizards) is a group of usually legless
squamates, comprising over 180 extant species. Amphisbaenians are characterized by their long bodies, the reduction or loss of the limbs, and rudimentary eyes. As many species have a pink body and scales arranged in rings, they have a superficial resemblance to
earthworms. While the genus
Bipes retains forelimbs, all other genera are limbless. Although superficially similar to the
snakes and
Dibamidae, recent phylogenetic studies suggest that they are most closely related to the
Lacertidae. Amphisbaenians are widely distributed, occurring in North America, Europe, Africa, South America, and the Caribbean. Most species are less than long. Little is known of them outside of their anatomy, and even that is difficult to study due to the mechanics of dissecting such small animals.