There are well over 3,000 known species of snakes in the world, with the number increasing as new ones are discovered. Geographically speaking, they are found in all the continents except Antarctica, but they are absent from a number of islands, including Greenland, Iceland, Ireland, and New Zealand. Snakes live in a wide variety of habitats, but are restricted in their distribution because, like other reptiles, they are cold-blooded and therefore have less control over their body temperatures than mammals. A snake must regulate its temperature by seeking out warmer or cooler conditions, as required. In regions with cold winters, snakes will go into a kind of hibernation in autumn, seeking out suitable frost-free places to keep warm.
Distribution
The majority of snakes live in tropical climates. Mammals, such as humans, can regulate their body temperatures internally, but snakes are dependent on their environment for maintaining a suitable temperature. When they get too hot, they move into the shade, and when they are too cool, they move into a sunny area. It is easier for them to live in areas where the temperature does not drop below 50°F (10°C), and, although they can survive at temperatures close to freezing point, they are not thought to be able to survive if their body temperatures drop below freezing. They are more efficient in warm weather, and in tropical areas, they can be active throughout the year.
Surviving the Winter
Snakes that live in temperate climates undergo a kind of hibernation known as brumation in the winter. In this state, the reptile remains awake, but inactive. It does not need to eat, and can survive many months without food, but it will emerge from time to time to drink water.
While in brumation, it will mostly remain hidden in a place that is protected from frost. These may be hollow tree trunks or stumps, caves, burrows within soil or sand, or under piles of leaves. Often, decaying organic matter in these places will give out some heat, keeping the temperature above freezing point. Sometimes a snake will share a hiding place with many others: this helps to keep temperatures up. In populated areas, snakes may occasionally venture into human dwellings or other buildings, such as huts, sheds or garages, or into piles of rubbish or garden waste, with a view to spending the winter there.
Habitats and Adaptations
Snakes have adapted to a variety of very different habitats. They can live in forests, prairies, deserts or even bodies of water, but will typically be found where there is an ample supply of food, such as rodents, small reptiles, birds and frogs. Snakes eat their food whole and often while it is still alive. While some types — for example, boa constrictors — will squeeze their prey to death before eating it, most unhinge their jaw and swallow their prey alive. A snake’s teeth are pointed backward, which prevents the live prey from darting out of the snake’s mouth before it swallows.
At first glance, it would seem that all snakes are built the same way, just in different sizes and colors; however, on closer examination, differences in body plan can be found, determined by the environment in which the snakes live. In tropical forest areas, many species live in trees, and these tend to have relatively long, slender bodies, suitable for wrapping around branches. Those that spend most of their time on the ground are more compact, with bodies made for burrowing. Snakes that live near water often have a flattened shape that helps them swim efficiently.
Snakes and People
Snakes often inspire fear in humans, but they will generally do their best to avoid people. The reptiles are very sensitive to vibration, and will respond to footsteps by quickly slithering off to a suitable hiding place. Even in areas where these creatures are common, people may never see one, and might pass very close by one without being aware of it. For people with an interest in snakes, often the best chance of observation is when one is sunning itself on open ground or a rock, to keep up its body temperature.
Venomous snakes do pose a potential hazard, but they will not attack people unless they feel threatened, and cannot escape. Snake bites are extremely unlikely when walking outdoors; the greatest risk is in disturbing a resting snake in its hiding place. In areas where venomous snakes are known to occur, caution should be exercised in reaching into natural crevices or, in populated areas, anything in which a snake might hide, such as pot, a pile of household rubbish or garden waste, or even an old boot.