Endotherm
An endotherm is an animal that can control its body temperature by the regulation of its metabolic rate. Endotherms include birds, mammals, and insects. The advantages of endothermy are increased enzyme activity and a constant body temperature, allowing these animals to be active in cold temperatures. On the other hand, the disadvantage is the need to maintain thermoregulation, even during inactivity, otherwise the organism will die.
In winter, there may not be enough food to enable an endotherm to keep its metabolic rate stable all day, so some organisms go into a controlled state of hypothermia called hibernation, or torpor. This deliberately lowers the body temperature to conserve energy. In hot weather, endotherms expend considerable energy to avoid overheating: they may pant, sweat, lick, or seek shelter or water.
See also