What Are the Major Characteristics of Reptiles?

There are over 6,500 species of reptiles.

Reptile species vary dramatically in size and appearance. A reptile can be as small as a tiny gecko that is less than an inch long or as big as a crocodile, which can weigh more than a ton.

Identification

Reptiles are vertebrates (they have a backbone), have scaly skin and lay eggs. They have four legs or are descended from creatures with four legs.

Temperature Regulation

Reptiles are ectotherms, meaning they cannot produce their own body heat. Their body temperature changes with the temperature of their environment. Strictly speaking, though, they are not "cold-blooded," because when they are in a hot environment, they can maintain a high body temperature.

Types

There are four types (orders) of reptiles: testudines contains turtles and tortoises; squamata contains lizards and snakes; crocodylia contains crocodiles and alligators; and rhynchocephalia contains only two species of the lizard-like tuataras, which live off the coast of New Zealand.

References

• San Diego Natural History Museum: Reptiles
• The Encyclopedia of Earth: Reptiles
• San Diego Zoo: Animal Bytes: Reptiles
• San Diego Natural History Museum: A Teacher's Guide to Reptiles