Getting to Know Reptiles

REPTILES :

Snakes, crocodiles and alligators, lizards, and turtles might not look alike at first glance, but they all share certain features. These animals, plus the tuataras that resemble a cross between a prehistoric dinosaur and a present-day lizard, are reptiles. In all, the world holds 285 species of turtles, 23 crocodiles and alligators, two tuataras, 4,450 lizards, and 2,900 snakes. Scientists suspect that hundreds of other reptile species have yet to be discovered.

Scales :

Almost all reptiles have thick tough skin with scales or scutes. Alligators have large heavy rectangular scales covering their bodies, while snakes often have thinner overlapping scales. Most snakes have larger and wider belly scales, which are known as scutes. Even turtles have noticeable scales on the legs and head. These scales and scutes can help protect the reptile from scraping its skin on the ground or from dangerous attacks by other animals that want to eat it. For land-living reptiles, the scales can also keep the body from drying out too quickly. Besides the scales on their legs, turtles also have a different type of scutes. The tops of the upper and lower shell are divided into large pieces, which are also known as scutes. Reptiles come in many different sizes and colors. Some snakes grow to less than 12 inches (30.5 centimeters) long as adults, while others can reach 25 feet (7.7 meters). Likewise, a whole range of sizes separate the smallest of turtles at just a few inches (centimeters) long from the largest, which have shells that can reach 8 feet (2.4 meters) in length. Many reptiles have dull drab colors that help them blend into their surroundings, but others are very brightly colored and patterned.

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Body temperature :

Reptiles are often called cold-blooded animals, but this description is only correct sometimes. A reptile actually changes its body temperature, becoming hotter when the outside temperature is warm, and colder when the outside temperature is cool. In other words, a reptile is only “cold blooded” on cold days. This changing body temperature is called ectothermy (EKtoe- ther-mee): ecto means outside and thermy refers to the

temperature. Reptiles, then, are ectothermic animals. In “warmblooded” animals, such as human beings, the body has to stay about the same temperature all the time. If a person’s body temperature rises or falls more than just a few degrees, he or she can die. For the ectothermic reptiles, however, their body temperatures can swing 20 to 30° F (7 to 13° C)—and sometimes more—in a single day without causing any harm. Because they are ectothermic, reptiles do not have to use their energy to stay warm. Instead, they can simply let the sun warm them up by sunbathing, or basking, on a forest path or the shore of a river or lake. Ectothermy can also have a downside. Reptiles are slower on cooler days or in the cool morning or evening air, which can make them easy prey for attackers. Most reptiles, however, hide themselves away when their bodies start to chill.

Venom :

Not all reptiles are venomous, but many snakes and a few lizards are. Venom is a type of toxin, or poison. Venomous snakes generally have two fangs in their upper jaw— sometimes in the front of the mouth and sometimes in back. These fangs usually have grooves that send the venom down the tooth and into the prey. Unlike the snakes, the two venomous lizards, the Gila monster and the Mexican beaded lizard, store their venom in the lower jaw and deliver it through grooves in numerous teeth.