Added 1999. Last updated January 2003.


Snakes are a large group of animals belonging to the reptile class (Class Reptilia). Their closest living relatives are the lizards, plus an obscure group of reptiles, the amphisbaenians or "worm-lizards". Together, lizards, snakes and amphisbaenians form the order Squamata. This in turn is related to the other reptilian groups, living and extinct: the crocodiles, turtles and tuatara (an endangered lizard-like creature from New Zealand) of our present age, plus the dinosaurs and other prehistoric reptiles.

Snakes began to appear about 90 million years ago, but their origins are still in doubt. Most evolutionists believe that they are descendants of lizards that burrowed, lost their limbs in so doing and adapted their vision, and then re-emerged somehow into broad daylight without legs or eyelids. The tiny girdles found at the rear of pythons and boas are often considered to be vestigial remnants of limbs. On the other hand, the long-held belief that the monitor lizards (Varanidae) were a link to the putative lizard ancestors of snakes has recently been questioned.

Snakes can normally be characterised by a dry, watertight and scaly skin, lidless eyes, forked tongue and (when eating) the ability to swallow prey much larger than their own head. All snakes are carnivorous, although their prey varies. There is less diversity amongst snakes than amongst lizards, but even so snakes do vary tremendously in size, colouring and habitat. Many snakes make excellent pets, but it should be noted that the better-known ones such as pythons, boas and cobras either have special needs or legal restrictions on their ownership. As a rule, most people should not keep venomous snakes. This applies especially in the UK, where the population density is such that an escaping venomous snake could cause real damage. In any event the keeping of venomous snakes in most places is tightly regulated by law and a system of licensing.

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