Vipers are snakes that have a pair of long, sharp, hollow fangs. Some of the deadliest snakes in the world are vipers. Well-known types include rattlesnakes and adders.

Where vipers live

There are about 200 types of vipers. They are found on all the continents except Australia and Antarctica. Highly dangerous vipers include the rattlesnakes in North America, the lanceheads in Central and South America, the adders in Europe, and the Russell's viper in Asia. The most dangerous vipers are probably the saw-scaled vipers, which many believe cause more human deaths than any other snake. These quick-tempered vipers are common in the dry parts of Africa and Asia. Because they live near people's homes and are small and easily hidden, people often step on them and get bitten.

Vipers may live on the ground or in trees, from deserts to rain forests. Despite the dangerous nature of these snakes, some people try to capture them. Conservation groups discourage people from acquiring vipers because the existence of some of them is threatened in the wild.

Physical characteristics

Most vipers have stout bodies that range in length from less than 12 inches (30 centimeters) to more than 10 feet (3 meters). Tree-dwelling vipers tend to be more slender. A viper's coloring and markings help it blend in with the environment. Therefore tree dwellers may be green, forest vipers may be brown with various dark markings, and desert vipers may be tan with light markings.

Most vipers have ridged scales, which may be raised at the edges or upright over the eyes or snout. These scales make it seem like the snake has horns. Some snakes, including saw-scaled vipers, rub their scales together to produce a rasping noise that serves as a warning. Rattlesnakes have specialized tail ends that they shake when threatened.

Vipers have triangular heads. Their fangs can fold back against the roof of their mouth. When vipers strike, their jaws open wide and their fangs swing down into position, ready to stab. Vipers in the Americas and some in Southern Asia also have heat-sensitive pits on the side of their face. The pits aid them in detecting and striking prey, even in the dark. Such snakes are called pit vipers.

Behavior

Most vipers bear live young. Newborns have both venom and fangs. As vipers grow, they lose their old fangs and get new ones every few months.

Vipers may be active by day or by night. They hunt by lying with their bodies coiled, waiting for small mammals or birds to come within striking distance. When an animal approaches, vipers strike with lightning speed, stabbing their prey with their fangs. Powerful muscles squeeze the venom glands in the head and inject venom through the fangs and into the prey. The venom attacks the blood and destroys tissue. Usually the prey runs off and dies nearby. The viper then tracks the prey by scent and swallows it.