Agamid A lizard with sturdy legs, also known as the dragon lizard. Males are often brightly coloured. Agamids include bearded dragons and frilled lizards.

Alligator A large reptile related to crocodiles. Alligators have wider snouts than other crocodilians. The two main species of alligator are the American alligator, which lives in the swamps of southeast North America, and the rare Chinese alligator, which lives in the Yangtze River valley. Alligators can grow up to 6 metres (20 feet) long.

Blind snake A small, tropical, burrowing snake. Blind snakes have tiny eyes and rounded heads for pushing through soil.

Boa A constrictor from Central and South America that gives birth to live young. Boas include the 4-metre (13-foot) boa constrictor and the anaconda, which grows up to 8.5 metres (28 feet) long.

Caiman A relative of the alligator from Central and South America that has heavily armoured undersides. Caimans are usually smaller than alligators but the black caiman can grow up to 5 metres (16 feet) long.

Carapace The upper part of the shell of a turtle. It is joined to the animal’s ribs and backbone and linked to the plastron by bony bridges at the side of the body. Most turtles have a flat, streamlined carapace, suited to swimming. Tortoises have an arched carapace, covered with horny scales.

Chameleon A lizard with a prehensile tail and grasping feet. Chameleons have long, sticky tongues for catching insects and change colour to match their surroundings.

Cobra A venomous snake with a hood of skin behind its head. Cobras live in Africa and Asia. They have two fangs at the front of their mouths, used to inject a venom that paralyses, then kills their prey. The king cobra is the largest venomous snake, growing up to 5.5 metres (18 feet) long.

Constrictor A snake that kills its prey by coiling around it and suffocating it. Every time the prey exhales, the snake tightens its coils, until the victim cannot breathe. Most constrictors are well-camouflaged.

Colubrid A snake with a single row of large scales on its belly. Most, but not all, species are non-venomous. Around two-thirds of all snakes are colubrids. They include garter snakes, milk snakes and tree snakes.

Coral snake A slender, venomous snake with red, black, yellow or white stripes. These warn other animals it is dangerous.

Crocodile An aquatic, predatory reptile with a long jaw and bony plates of armour on the top of its body. One pair of teeth in the lower jaw is always visible even when a crocodile’s mouth is closed. Crocodiles mostly live in tropical rivers and lakes. The largest species are the Nile crocodile and the saltwater crocodile, both of which grow up to 7 metres (23 feet) long. They can easily bring down large prey such as antelope, which they ambush at the water’s edge, dragging them underwater to drown.

Crocodilians The order of reptiles that includes crocodiles, alligators, gharials and caimans. Crocodilians are aquatic, predatory reptiles with long jaws and tails, short limbs and sharp teeth. Because their eyes and nostrils are on top of their heads, they can hide with their bodies almost completely underwater. Most live in rivers and lakes, feeding on a range of prey, including fish, birds and mammals.

Cryptodira Turtles, also known as “hidden neck” turtles, that can hide their heads inside their shells. They include most freshwater turtles, sea turtles and all tortoises.

Flying lizard A lizard from Southeast Asia, with flaps of skin along its body that act as parachutes, helping it to glide between trees. The flaps are supported by rib extensions, which lie flat when not in use.

Freshwater turtle A turtle that lives in freshwater ponds, lakes or rivers. Freshwater turtles, sometimes called terrapins, include soft-shelled turtles, diamondback terrapins, painted turtles, and the aggressive snapping turtles.

Gecko A small, thick-bodied lizard. Geckos have hairs on their toes, which enable them to grip on to smooth surfaces. They are the only lizards that can call to one another.

Gharial An aquatic reptile also known as the gavial. The gharial has a long, narrow snout, lined with needle-like teeth and lives in rivers of the Indian subcontinent, feeding only on fish. It can reach lengths of up to 7 metres (23 feet) long and is a very agile swimmer.

Gila monster A venomous lizard from the deserts of North America. It is slow-moving and feeds mainly on eggs. It stores fat deposits in its large tail.

Iguana A herbivorous lizard from the tropics. The green iguana is a tree-dwelling lizard with a crest of spines down its back. The marine iguana is the only sea-dwelling species of lizard. Other iguanas include anoles, basilisks and horned lizards.

Legless lizard A limbless lizard such as a slow worm or glass lizard. The eyelids and ear openings of legless lizards distinguish them from snakes.

Mamba A fast, venomous snake from Africa. Mambas can move at up to 20 km/h (12 mph). The most feared species is the black mamba, whose venom can kill a human in 20 minutes. It has a grey body and black mouth. The other species are all green.

Monitor lizard A large, carnivorous lizard. Monitor lizards includes the water monitor, crocodile monitor and the 3-metre (10-foot) venomous Komodo dragon, the largest lizard in the world. It mostly eats carrion but can also ambush and kill large prey.

Plastron The flat, lower part of the shell of a turtle. It is joined to the animal’s breastbone and linked to the upper shell by bony bridges at the side of the body.

Pleurodira Turtles, sometimes called “side-necked turtles”, that cannot retract their heads inside their shells. Instead, when threatened, they fold their necks sideways to hide their heads under a lip of shell.

Python A constrictor with a heat-sensitive organ on its head, used to find prey. The reticulated python, which grows up to 10 metres (33 feet) long, is the longest snake in the world.

Rattlesnake A venomous American viper, with a rattle in its tail. When agitated, it vibrates its tail to make a warning sound. Most species have diamond-patterned markings and all give birth to live young.

Sea snake A snake that lives in the ocean. There are around 60 species of sea snake, all of which are venomous. They have flattened tails to help them swim. Many species are striped.

Sea turtle An ocean-dwelling turtle. There are seven species: the flatback, green, hawksbill, Kemp’s ridley, olive ridley, leatherback and loggerhead turtles. Most feed on jellyfish, fish and crustaceans, except for the herbivorous green turtle. Turtles can hold their breath underwater for over three hours when asleep. The largest sea turtle is the 3-metre-long (10-foot) leatherback turtle.

Shieldtail snake A burrowing snake from Asia with a large scale at the end of its tail. All shieldtail species are non-venomous.

Skink A small lizard with a long body and short limbs. Some species have no limbs at all. Many skinks are good burrowers.

Tortoise A land-dwelling turtle with stumpy, scaly legs and short toes. Tortoises move slowly, relying on their shells to protect them from predators. They are mainly plant-eaters. Giant tortoises can measure over 1 metre (3 feet) long and live for around 200 years.

Tuatara A lizard-shaped reptile from New Zealand. It is not related to lizards, but is the only member of an order of reptiles that lived on Earth even before the dinosaurs. It is green with a crest of skin down its back that can be raised as a threat. The tuatara feeds at night, hunting insects, worms and small lizards. It may live for over 120 years.

Venom A poisonous substance found in the bodies of some animals. Venomous snakes have venom glands in their heads. Venom is injected through their fangs in order to kill prey or defend themselves.

Viper A venomous snake with long, hollow fangs that fold back inside its mouth until it strikes. Pit vipers, such as rattlesnakes, have heat-sensitive organs, used to locate prey. Old world vipers, such as puff adders, do not.

Wall lizard A lizard from Europe, Asia and Africa with a slim body, long tail and large scales on its head and belly. Some species give birth to live young.

Whiptail lizard A narrow lizard with a long tail. Whiptail lizards are the American equivalent of the wall lizards.

Consultant: Chris Jarvis