THE ANIMAL FILES

Common slow worm

Anguis fragilis

A legless lizard can blink.

The common slow worm is a legless lizard, not a snake or an earthworm. Movable eyelids, smooth scales and a tail that can be shed help explain the distinction. It feeds chiefly on small invertebrates in sheltered, often moist places.[1]

Follow the evidence ↓
Common slow worm
Image: Tom.66.cz · Commons · CC BY-SA 4.0
Identity
Legless lizard[1]
Eyes
Movable eyelids[1]
Food
Slugs, snails and earthworms[1]

Looking beyond absent legs

The eyes have movable lids, unlike the fused covering over snake eyes. Small scales cover the body and bony plates lie underneath. A short, broad tongue samples odours, with the mouth slightly opened during the action. These anatomical details make a stronger comparison than the shared long shape alone.[1]

A tail that does not fully return

When seized by a predator, the tail can be shed. Regrowth forms a shorter replacement rather than restoring the original length. Tail loss can help escape, but regeneration should not be described as limitless or as returning an identical new body part. The shortened tail records a past event.[1]

Warmth beneath shelter

Slow worms often use cover that has been warmed by sunlight rather than basking openly. Activity varies with conditions and can increase around dawn, twilight or after rain. Moist vegetation offers invertebrate prey, while young are born in a thin membrane they soon break through.[1]

A COMMON MIX-UP

Does having no legs make it a snake?

No. Its eyelids and other anatomy identify it as a legless lizard.[1]

TRY A LITTLE REASONING

Why is a regenerated short tail not evidence that the animal is simply young?

Reveal the explanation

The replacement after tail loss remains shorter; length can reflect injury history as well as growth.[1]

Sources & editorial notes

Adapted and translated from the cited Wikipedia revisions, with source-linked reasoning. Image credit and licence are listed separately above.

Adapted and translated from Wikipedia contributors; exact revisions are linked below. CC BY-SA 4.0

  1. Wikipedia contributors — Anguis fragilis (adapted and translated; exact revision)
  2. NCBI Taxonomy — Anguis fragilis (identity and game lineage)

Last fact check:

One discovery leads to another

Gila monsterBeaded skin, a searching tongue and a fat-storing tail.Heloderma suspectum ↗Komodo dragonThe forked tongue samples chemicals rather than frightening prey by appearance.Varanus komodoensis ↗Green iguanaLiving in trees does not rule out a swim.Iguana iguana ↗