Reptiles are cold-blooded vertebrate (has a backbone) animals. Reptiles are ectothermic, meaning that they rely on the Sun’s energy to heat them up and match the temperature in the air around them. When it is cold outside, reptiles become more inactive in order to maintain a body temperature and are very active when it warms up! Most reptiles have skin that is covered in scales or bony plates. Reptiles breathe using lungs and grow up on land. Examples of reptiles are snakes, lizards, and crocodiles.