Worm Lizards Dig Like Earthworms

Navigating the world by ramming your head through soil requires some serious anatomical specialization. For the amphisbaenian, this means a skull that is heavily reinforced and often fused into a solid, shovel-like tool for digging. The name "amphisbaenian" itself comes from Greek, meaning "to go both ways," a direct reference to their ability to move forwards and backwards with equal agility within their narrow, self-made tunnels. Unlike a snake, which primarily uses its body to propel itself, a worm lizard leads with its head, compacting the earth as it pushes forward.

This remarkable burrowing method is part of a larger story of convergent evolution. While they are true reptiles, their legless, cylindrical bodies and ringed skin make them look uncannily like the earthworms they often live alongside. This is no coincidence; both creatures adapted to the intense pressures of a subterranean life, resulting in similar body plans. The worm lizard’s skin, however, is only loosely attached to its skeleton. This allows it to bunch up and stretch out its skin in a "concertina" motion, gripping the sides of its burrow to pull its body forward—a reptilian version of the peristalsis used by an invertebrate earthworm.