Alligators are closely related to crocodiles. Alligators have wider and more rounded snouts than crocodiles. The two main kinds are the American alligator, which lives in the swamps of southeastern United States, and the rare Chinese alligator, which lives in the Yangtze river valley. Alligators can grow up to 6 metres (20 feet) long.

The anaconda is a type of boa from South America. One of the world’s largest and heaviest snakes, it grows up to 9 metres (30 ft) long. It spends much of its life wallowing in shallow water while it waits for an unwary animal to come within range.

Caimans

Caimans are relatives of the alligators. They have thick scales on their undersides. Living in Central and South America, they are usually smaller than alligators, although the black caiman can grow up to 5 metres (16 feet) long.

Chameleons are slow-moving lizards that live in trees. They have grasping feet and long, prehensile tails to help them grip branches and climb. They can change colour to blend in with their background. Their eyes can move in different directions and see different objects at the same time.

Most chameleons eat insects. When they spot one, quick as a flash they flick out their extremely long, sticky tongue to grab it and pull it into their mouth.

Cobras

Cobras are snakes with a hood of skin behind their heads. They kill their prey with a venomous bite. They have two fangs at the front of their mouths. When they bite, they inject deadly venom into their victim. They eat mainly other snakes, lizards, small mammals and frogs. They spread out their hood and hiss to frighten off attackers. The king cobra, from Southeast Asia, feeds mainly on other snakes. Up to 5.5 metres (18 ft) long, it is the largest venomous snake in the world.

Geckos

Geckos are types of lizard. They have tiny hairs on their toe pads. These enable them to grip on to smooth surfaces and even walk upside down. Geckos are hunted by many animals, including birds of prey, snakes, monkeys and small cats. 

The colours and patterns on their bodies help camouflage them. Like other lizards, they can also break off their own tail if necessary. Most geckos have no eyelids and cannot blink, so they lick their eyes to keep them clean and moist. 

The marine iguana lives in the sea. It is the only sea-living lizard. It feeds on seaweed and algae in the waters of the Galapagos Islands. It can dive more than 15 metres (50 feet) deep in search of their food, using its flattened tail to propel itself through the water.

Komodo dragon

The Komodo dragon is a member of the monitor family. It is the largest lizard in the world. It can grow up to 3 metres (10 feet) long. It lives only on a few islands in Indonesia. Searching for food alone, it mostly feeds on carcasses of animals that are already dead, but will also hunt live prey—wild pigs, deer and goats. It can open its jaws wide enough to swallow some small prey whole.

Pythons

Pythons are large, constricting snakes. They lie in wait, hidden by their camouflage patterning, before striking suddenly at passing prey. They then coil their muscular bodies around their victim until it can no longer breathe. They then swallow their prey whole. It may take several days or even weeks to digest. The Indian python, from southeast Asia, hunts rodents and even small deer at night. The reticulated python, which grows up to 10 metres (33 feet) long, is the longest snake in the world.

Tuatara

The tuatara, from New Zealand, is only distantly related to lizards, despite its close resemblance. It has a crest of skin down its back that it raises when threatened. It basks in the sun during the day and feeds at night, hunting insects, worms and small lizards. It also eats bird's eggs and chicks. The tuatara has a third "eye" on the top of its head. This is only visible in hatchlings, however. After a few months, it is covered over by scales.

All turtles lay eggs on land. Some large sea turtles return to the same beaches every year to lay them. They dig holes in the sand, lay their eggs, then cover them over. Then they return to the water. After hatching, the young must dig their way to the surface. They run across the beach to reach the sea.

Vipers

Vipers are snakes that kill their prey with their venomous bite. Vipers have long fangs that fold back inside their mouths until they strike. Pit vipers, from the Americas, include the rattlesnake family. These snakes have a "rattle" at the end of their tail. It is made of loose rings of hard skin. They shake their rattle to scare attackers away. Rattlesnakes themselves prey on small mammals and birds.