Slow worms (Anguis fragilis) are living evidence that names and appearances can be deceptive. The first thing anyone will tell you about a slow worm is that it is a lizard, not a snake. They look similar to snakes, because these lizards have evolved in such a way that they no longer need legs – a similar evolutionary process that gave rise to the snakes.
There are some tell-tale signs that these little creatures are lizards. They have eyelids, and blink; snakes, on the other hand, don’t. Slow worms’ tongues are rounded – in contrast to snakes, who have unmistakable forked tongues. Like many other lizards, the slow worm can detach its tail when trying to escape from a predator. And a slow worm’s head is usually the same width as its body – that is, there’s no narrowing behind their heads – whereas snakes have an obvious ‘neck’.