Reptiles

Worm Lizard

Amphisbaenia · also called worm lizards, amphisbaenians

Least Concern insectivorecarnivore Temperate grassland Temperate forest Desert

A worm lizard looks exactly like what its name says: a fat pink earthworm, ringed along its whole length, with no obvious head or tail. It is actually a reptile, but not a snake and not quite a lizard either — it belongs to its own ancient branch of the squamates, and it has spent so long underground that its eyes are just light patches under the skin and its skull has fused into a solid digging wedge.

Overview

Worm lizards are the Amphisbaenia, about 200 species in the warm parts of the Americas, Africa, the Middle East, and the Mediterranean. They are squamates — the order that holds snakes and lizards — but a separate lineage that lost its limbs and went underground independently, so they are usually treated as a third group. They are carnivores of soil invertebrates, mostly ants, termites, and grubs, found by vibration and smell in the tunnels.

Built for the dark

The skull is a solid battering ram — rounded, spade-shaped, or wedge-shaped depending on how the species digs — and the animal compacts soil by ramming and twisting. The loose ringed skin slides over the body, anchoring against the tunnel wall so the worm lizard hauls itself forward in a concertina motion. It moves backwards as easily as forwards, which, with a blunt tail that resembles a head, gave rise to the ancient myth of the two-headed amphisbaena.

One exception

Nearly all amphisbaenians are entirely limbless, but the three Bipes mole lizards of Baja California keep a pair of short, strong front legs just behind the head to help start a burrow.

Status

Not broadly assessed and mostly hidden, but the group is not considered threatened and widespread species are locally common. Small-range island and soil specialists are poorly known and potentially vulnerable to land clearing and insecticide use that removes their ant and termite prey.

Worm Lizard: common questions

Is a worm lizard a snake or a lizard?

Neither, exactly. Worm lizards, or amphisbaenians, belong to the squamates, the reptile order that contains snakes and lizards, but genetic and anatomical studies place them as their own separate lineage that split off long ago and evolved limblessness and a burrowing life independently of snakes. Some classifications nest them within the lizards, close to the wall lizards, and technically a snake is also a highly modified lizard, so the labels get slippery. The practical answer is that a worm lizard is a distinct kind of squamate, and calling it the third group alongside snakes and lizards captures how different it is from both.

Why is it called amphisbaena, and can it really move both ways?

The name is from the Greek amphis, both ways, and bainein, to go, and it refers to the animal's ability to travel backwards along its tunnel as easily as forwards, helped by a short blunt tail that from a distance looks much like the head. Ancient writers took this literally and described the amphisbaena as a serpent with a head at each end, and the two-headed amphisbaena became a fixture of classical and medieval bestiaries and later of heraldry. The real animal has one head; the tail is simply shaped and used so that the worm lizard is not committed to one direction underground.

How is a worm lizard different from a caecilian?

They look remarkably alike, both being limbless, ringed, blunt-headed, burrowing animals, but they are not related. A worm lizard is a reptile, a squamate with scales, lungs, and internal fertilisation, that lays eggs or bears live young on land. A caecilian is an amphibian, related to frogs and salamanders, with moist glandular skin, a two-part lifecycle in some species, and a pair of retractable chemical-sensing tentacles on the face that worm lizards lack. Their similarity is one of the clearer cases of convergent evolution, two unrelated groups shaped into the same worm-like form by the demands of moving through soil.

Are worm lizards dangerous, and where might I see one?

They are harmless to people. They are not venomous, and although a large one can give a surprisingly firm pinch with its interlocking teeth if picked up, they are small, slow-moving, and defensive rather than aggressive. Most people who encounter a worm lizard do so by turning over a log or a rock, digging in a garden, or finding one on the surface after heavy rain has flooded its tunnels, especially around the Mediterranean and in the southern United States and Latin America. On the surface they are often mistaken for large earthworms or for baby snakes, and the best thing to do is simply place them back on damp soil in the shade.

Sources & further reading

Written by HideShark Editorial Team · reviewed by HideShark Science Desk. Published September 10, 2026. Last updated September 10, 2026.

Quick facts

Scientific name: Amphisbaenia
Diet: Soil invertebrates located by vibration and smell in the tunnels, including ants, termites, beetle larvae, earthworms, spiders, and other small arthropods, seized with strong interlocking teeth and, for larger prey, torn apart by the worm lizard spinning its body
Not a snake, not a lizard: Amphisbaenians are squamates, the same order as snakes and lizards, but they form their own distinct group of about 200 species, having independently lost their limbs and adapted to a life spent almost entirely underground, so they are usually treated as a third branch alongside snakes and lizards
A head like a digging tool: The skull is fused into a solid, blunt battering ram, and different families have different shapes, a rounded head for general burrowing, a vertical spade for keeled diggers, and a horizontal wedge for others, all used to compact soil by ramming and twisting rather than by scooping
It goes both ways: The name amphisbaena comes from a Greek word meaning to go in both directions, because the blunt tail looks like a second head and the animal can move backwards along its tunnel just as smoothly as forwards, which fed the ancient myth of a two-headed serpent
Skin that slides on the body: The tube-shaped body is ringed with square scales in bands called annuli, and the skin is attached loosely so the animal can move within it, anchoring the skin against the tunnel wall and then pulling the body forward through it in a concertina motion, a very different mechanism from a snake's belly-scale crawl
Eyes and ears buried under skin: Living in the dark, worm lizards have tiny eyes reduced to light-sensing patches beneath translucent skin and no external ear opening, and they navigate almost entirely by touch, smell, and detecting vibrations, though they hear low-frequency sound well through the ground
One family kept its front legs: Almost all amphisbaenians are completely limbless, but the three species of Bipes, the mole lizards of Baja California in Mexico, retain a pair of short, strong, mole-like front legs just behind the head, used to help start a burrow, while the rest of the body is legless
Range: Warm regions of the Americas, Africa, the Middle East, and the Mediterranean, with the greatest diversity in South America and sub-Saharan Africa, plus species in the West Indies, Florida, Iberia, North Africa, Anatolia, and the Arabian Peninsula, living underground in loose or friable soil, sand, leaf litter, and the mounds of ants and termites, in habitats from rainforest and savanna to desert and farmland.
Conservation status: Least Concern ≈ Most amphisbaenian species have not been individually assessed and, being hidden, are hard to survey, but the group as a whole is not considered threatened, and the widespread species are locally common in suitable soil across their ranges. A number of species with very small ranges, particularly on islands and in specific soil types, are poorly known and potentially vulnerable to habitat conversion, and some are affected by the loss of the ant and termite colonies they feed on when land is cleared and treated with insecticides in the wild