The whole snake family has a rather strange evolutionary history. Snakes’ ancient ancestors (who were also the ancestors of lizards) progressed from above-ground life, to living and moving about underground, burrowing through the earth. This subterranean lifestyle meant they’ve evolved to have relatively poor eyesight. To compensate, snakes picture their surroundings using their tongues, which collect chemicals in the air. On retracting the tongue, this transfers the chemicals to their ‘smell’ organ (called Jacobson’s organ). The adder (Vipera berus) is, of course, also unique in being Britain’s only venomous snake. They use venom to help kill their prey, small mammals and chicks. But adders should not be feared – they will only bite you to defend themselves from a serious threat, like being handled or stepped on.Continue reading “Species Guide: The Adder”
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’.
The grass snake (Natrix natrix) is the UK’s largest snake species, and arguably our most familiar snake – because they have a habit of visiting gardens in search of a meal, or a place to lay their eggs. They’re striking to look at, with attractive colouration and golden eyes. They aren’t to be feared – they’re shy, they don’t bite, and are not venomous. Continue reading “Species Guide: The Grass Snake”