DK Science: Reptiles
Reptiles are ectothermic (cold-blooded) animals. They cannot generate their own body heat and many bask in the sun to get warm. Tough, dry scales cover their skin, preventing the loss of too much water, and protecting the reptile from harm. Reptiles with legs have a sprawling gait because their limbs are jointed to the side, not below as in birds or mammals.
This large lizard lives in trees. Its green, scale-covered skin provides camouflage among the leaves and its long, clawed fingers and toes help the iguana climb well. If attacked, it uses its long tail as a whip. Young iguanas can shed their tails and regrow the missing part.
The leopard tortoise, like all reptiles, emerges fully formed from its egg and has to fend for itself immediately. For some reptiles, the sex of the young depends on the temperature of the eggs as the embryos develop.
A rattlesnake bites its prey and injects poison through long fangs. The fangs fold back against the roof of the mouth when they are not in use, and drop down automatically as the mouth opens. Two heat-sensitive pits between the eyes and nose help the rattlesnake to locate its prey.
The largest of the lizards, the Komodo dragon is found on only a few islands in Indonesia. It uses its excellent sense of smell to find prey. Unlike mammals, reptiles cannot chew food – the Komodo dragon tears off chunks of flesh with its jagged teeth.
Reptiles have a tough skin, with scales made of keratin. They lay soft-shelled eggs, usually on land. There are nearly 8,000 species.
