The physique temperature of cold-blooded animals is decided by the temperature of their setting. This contrasts with warm-blooded animals—the body temperature of which is maintained inside a small, constant range largely unbiased of exterior circumstances. Because they are cold-blooded, or ectothermic, reptiles should bask in the sun to extend their internal physique temperatures, which in turn allows for a better level of exercise . When they overheat, reptiles shelter in the shade to chill back right down to a safer temperature. Reptiles are amniote animals, which implies that the eggs, laid by females, comprise an elastic sac inside which the embryo develops.