worm lizard

Worm lizards Fossil range: Cretaceous[1] - Recent
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Sauropsida
Order:	Squamata
Suborder:	Amphisbaenia Gray, 1844
Families
Amphisbaenidae Bipedidae Rhineuridae Trogonophidae
black: range of Amphisbaenia

The Amphisbaenia are a usually legless suborder of squamates closely related to lizards and snakes. As many species possess a pink body coloration and scales arranged in rings, they have a superficial resemblance to earthworms. They are very poorly understood, due to their burrowing lifestyle and general rarity. Most species are found in Africa and South America, with a few in other parts of the world. Little is known of them outside of their anatomy, and even that is difficult to study due to the mechanics of dissecting something so small. Most species are less than 6 inches (150 mm) long.

Description

Close-up of the head of Rhineura

Despite a superficial resemblance to some primitive snakes, amphisbaenians have many unique features that distinguish them from other reptiles. Internally, their right lung is reduced in size to fit their narrow bodies, whereas in snakes, it is always the left lung. Their skeletal structure and skin are also different from those of other squamates.^[2]

The head is stout, not set off from the neck, and either rounded, sloped, or sloped with a ridge down the middle. Most of the skull is solid bone, and they have a distinctive single median tooth in the upper jaw. They have no outer ears, and the eyes are deeply recessed and covered with skin and scales. The body is elongated, and the tail truncates in a manner that vaguely resembles the head. Their name is derived from Amphisbaena, a mythical serpent with a head at each end. The four species of ajolote are unusual in having a pair of forelimbs, but all limbless species have some remnants of the pelvic and pectoral girdles embedded within the body musculature.

The skin of amphisbaenians is only loosely attached to the body, and they move using an accordion-like motion, in which the skin moves and the body seemingly just drags along behind it. Uniquely, they are also able to perform this motion in reverse just as effectively.

Amphisbaenians are carnivorous, able to tear chunks out of larger prey with their powerful, interlocking teeth. Like lizards, some species are able to shed their tail (autotomy). Most species lay eggs, although at least some are known to be viviparous.^[2]

The white worm lizard (Amphisbaena alba) is often found in association with leaf cutter ants. It is thought this reptile forages in the ant's deep galleries where the insects deposit their waste. The larvae of certain large beetles live in these galleries and it is these the reptile preys on.^[3]

Families

Order: Squamata

• Suborder: AMPHISBAENIA
  • Family: Amphisbaenidae - Gray, 1865 -- Amphisbaenids, tropical worm lizards^[4]
  • Family: Bipedidae - Taylor, 1951 -- Ajolotes^[5]
  • Family: Rhineuridae - Vanzolini, 1951 -- North American worm lizards^[6]
  • Family: Trogonophidae - Gray, 1865 -- Palearctic worm lizards^[7]

References