Why the garden visitor you mistake for a snake is actually a lizard

Nature · Published 3 October 2026 · Updated 25 October 2026 Swipe more like this →

In short: If you spot a slithering reptile in a British garden, it is likely a slow worm. Despite their serpentine appearance and name, these creatures are legless lizards. They possess unique survival tactics, including the ability to shed their tails and a rather pungent defense mechanism to deter hungry predators.

The slow worm (Anguis fragilis) is a master of disguise, frequently mistaken for a snake due to its elongated, limbless body. However, simple physical traits reveal its true identity. Unlike snakes, slow worms have eyelids and blink, possess a notched tongue, and lack a distinct neck. Their scales are smooth and non-overlapping, an adaptation that likely assists with their preferred lifestyle of burrowing through loose soil and decaying vegetation.

Evolution has driven the loss of limbs in various lizard species worldwide, a trait often associated with burrowing or navigating dense grass. While snakes and slow worms share a common need to shed skin as they grow, the process differs; slow worms shed in patches rather than a single piece. Their defensive repertoire is equally distinct. When threatened, they may freeze or flee, but if cornered, they can release a foul-smelling secretion. If that fails, they employ autotomy, detaching their tail to distract attackers.

This tail-shedding ability is so common that researchers estimate over half of the wild population—roughly 50 to 70 percent—have lost their original tails. While they can regrow a replacement, the new appendage is typically shorter and lacks the capacity to be detached again. Beyond these physical defenses, slow worms are highly sensitive to their environment, using their tongues to detect the scent of predators like snakes. They remain active from March until October, when they retreat underground to hibernate.

Leglessness has emerged independently across many lizard families, including the Anguidae, to which the slow worm belongs. Other examples range from the flap-footed pygopodids of Australia to the nearly blind burrowers of the Dibamidae family. Despite the variety of these legless forms, they remain distinct from snakes, which are characterized by different lung structures and shorter tails relative to their total body length.

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