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REPTILES

This group of scaly-skinned, backboned animals includes snakes, lizards, crocodiles, hard-shelled turtles, and the tuatara, from New Zealand. Most reptiles live on land, but turtles, crocodiles, and some snakes live in water. Nearly all reptiles are equipped with senses similar to humans.

WHAT DO REPTILES EAT?

Most reptiles are active predators. Lizards hunt mainly insects. Snakes target prey such as rodents and birds. Some snakes subdue their victims with VENOM. Crocodiles prey on creatures as large as wildebeest. Turtles and terrapins eat mainly fish and invertebrates. Tortoises, which live on land, feed mostly on plants.

CHAMELEON

Chameleons hunt by stealth, creeping forward until their insect prey is in reach. More than half of the 85 species of chameleon live on the island of Madagascar, including this Nosy Be chameleon.

RED-TAILED RACER

Snakes gather molecules with their tongues, then transfer them to a gland on the roof of the mouth called the Jacobson’s organ. This gland is very sensitive and can detect distant prey. Some vipers can detect the body heat of prey using special pits near their eyes.

HOW DO REPTILES ESCAPE FROM DANGER?

Many reptiles hide, or are camouflaged to blend in with their surroundings. Some are speedy and agile, and can scurry off at lightning speed. Others are brightly colored to warn predators that they are poisonous. Some lizards can break off their tail in order to escape, growing a new one through REGENERATION.

WHAT IS THE DIFFERENCE BETWEEN A TURTLE AND A TORTOISE?

Turtles live in water and tortoises live on land. Turtles from the same scientific family as tortoises are sometimes called terrapins. Terrapins have clawed feet and live in freshwater habitats. Tortoises, turtles, and terrapins have changed little in 200 million years. They all have bony or leathery shells.

GREEN TURTLE

The green turtle is one of just six sea-living turtle species. Its bony shell is covered with a layer of horn. The largest sea turtle, the leatherback, may reach 8 ft (2.5 m) in length.

HOW DO REPTILES REPRODUCE

Most reptiles lay eggs, but in a few snakes and lizards, the eggs develop inside the mother’s body so that she gives birth to live young. Crocodiles and tortoises lay hard-shelled eggs similar to bird’s eggs. Turtules, snakes, and most lizards lay eggs with softer leathery shells. Sea turtles lay their eggs on beaches.

HOW DO CROCODILES HUNT?

The 22 species of crocodiles and their relatives are fearsome predators. Crocodiles ambush large prey. They snatch victims from the water’s edge and drag them under to drown them. Crocodiles cannot chew, but may spin around to break the victim’s body into pieces.

REPTILE CLASSIFICATION

There are around 6,000 species of reptiles, split into four different orders.
Snakes and lizards belong to the same order—Squamata. There are around 3,000 species of lizards and 2,500 species of snakes.
The second-largest order, Chelonia, includes all turtles, tortoises, and terrapins.
Crocodiles and their relatives make up the order Crocodilia.
The tuatara is the last living member of its order. The rest died out 100 million years ago.

VENOM

The majority of snakes kill their prey with venom produced by glands in their heads. The glands pump poison through long, pointed teeth called fangs, which bite deep into their prey.

HOW MANY SNAKES ARE DEADLY TO HUMANS?

Fewer than 10 percent of snakes produce venom strong enough to kill a person. Vipers produce large quantities of venom—people bitten by diamondback rattlesnakes have been known to die in under an hour. The Australian inland taipan is thought to be the world’s most deadly snake. Sea snakes are also highly poisonous, but they rarely bite humans.

HOW DOES SNAKE VENOM WORK?

Snake venom works on victims in two main ways. The venom of snakes such as vipers causes death by damaging the prey’s body tissues and blood. Other snakes produce neurotoxins, which attack the victim’s nervous system, paralyzing the heart, breathing system, and muscles.

FANGS OUT

Vipers lift their fangs forward just before biting, as this model shows. At rest, the fangs are held against the roof of the mouth.

REGENERATION

Some animals are able to regenerate (regrow) tails, limbs, or other body parts lost in accidents or bitten off by predators. Among vertebrates (backboned animals), these species include lizards such as the tree skink (a kind of lizard) and the salamander (an amphibian).

WHY DO SOME LIZARDS SHED THEIR TAILS?

Losing all or part of the tail is a defense mechanism for some species of lizards. If grabbed by a predator, the tail breaks off at a fracture point, which minimizes bleeding, and continues to wriggle, distracting the predator while the lizard escapes. Within nine months, the tail regrows, stiffened by cartilage instead of bone.

BEFORE AND AFTER

The tree skink is just one of many lizards that can regenerate their tails. Before it was lost, the end of this lizard’s tail contained bones. Now those bones have been replaced by gristly cartilage.

WHICH OTHER ANIMALS REGENERATE BODY PARTS?

Starfish, sponges, flatworms, and crabs can also regrow body parts severed in accidents. Sponges have an even more amazing ability. When passed through a fine mesh, these simple multicellular animals are able to reassemble themselves. The cells seek each other out and join back together.

Copyright © 2007 Dorling Kindersley

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