amphisbaenians

Amphisbaenians, commonly called worm lizards, are a group of squamate reptiles adapted to a fossorial, or burrowing, lifestyle. They are generally elongated and limbless, though the family Bipedidae retains two forelimbs. Their skin is sculptured into ring-like annuli that aid movement through soil, and their heads are often blunt or shovel-shaped for digging. Eyes are small and usually covered by scales, and external ears are absent or greatly reduced.

Taxonomically, amphisbaenians form the infraorder Amphisbaenia within Squamata. Living amphisbaenians are traditionally divided into four families: Amphisbaenidae, Rhineuridae, Blanidae, and Bipedidae. The best-known representatives include numerous Amphisbaena species in Africa and parts of Europe and the Americas, the Florida worm lizard Rhineura, and the two-toed Bipes in Central America and northern Mexico. Classification has varied as new data emerge.

They occupy warm, often arid to moist habitats across Africa, parts of Europe and Asia, and the Americas, including the Caribbean. Amphisbaenians are primarily fossorial, spending much of their lives underground in loose soil, leaf litter, or abandoned burrows. They feed on small invertebrates such as insects, termites, and earthworms and are generally shy and rarely seen by non-specialists.

Reproduction varies by species; most lay eggs, but some give birth to live young. Because they are cryptic and have limited dispersal, many species have restricted or poorly known distributions, and habitat disturbance can threaten local populations. Overall conservation status ranges from data-deficient to threatened in some regions, reflecting the need for targeted field studies.