It may be the only venomous snake throughout much of its range, including England, but the adder is not an aggressive species and avoids conflict. The majority of members of the viper family are venomous, and the adder - is no exception.
African rock pythons live across Africa south of the Sahara Desert. They are found in both forested and savannah habitats. Large adults can consume juvenile crocodiles, small antelopes and domestic goats. The snake hunts in the dark.
The American alligator faced extinction in the last century because of hunting pressures, but now its survival seems assured. Young American alligators feed on insects, small fish and frogs. As they get bigger, they begin to take larger prey.
American crocodiles live in fresh water, such as rivers and lakes, but will venture out into coastal waters, especially near estuaries and in lagoons, where the water is brackish. They have also been known to attack humans.
Ball Pythons are Africa's smallest pythons. They are generally active at night, when they hunt using eyes that are well adapted to low light levels. They also have special heat-sensing pits around their mouths to detect prey in the dark.
Black caimans are the largest alligators in the Americas. Young black caimans rely heavily on aquatic crustaceans for food, especially crabs and crayfish. Adults eat fish, such as catfish and piranhas, and often take large rodents called capybaras.
This species is one of Africa's most feared snakes, because of its powerful venom and the speed at which it can move over the ground. It is an aggressive animal, armed with venom capable of killing humans in four hours.
The brown snake of eastern North and Central America occupies a range of habitats, from highland woods to salt-water marshes -in fact, anywhere with plenty of loose stones or other debris for it to hide beneath.
Crocodilians are an ancient group of reptiles. They include crocodiles, alligators, caimans and gharials. They all live in or near water. Most crocodilians in North and South America belong to the alligator and caiman group.
The cat snake lives in the Balkans and Greece. It is found as far north as Bulgaria and the northeast corner of Italy. The snake's range continues east through the Caucasus to western Asia. The snake is considered sacred on some Greek islands.