Most insects and fishes are partial endotherms. They retain metabolic body heat to warm certain parts of their body. In order to maintain a constant body temperature, terrestrial animals must have a high metabolic rate and the ability to dissipate heat when the ambient temperature is higher than body temperature. The major advantage of endothermy is that the animal's activity is not restricted at low ambient temperatures. Heat loss is reduced by feathers, hair and subcutansous fat.
Heat dissipation is accomplished by increasing the blood flow to the skin by vasodilation.
Heat loss is minimized by vasoconstricting the vessels supplying the skin. Countercurrent heat exchangers in the extremedies can help conserve heat or dissipate heat in birds and other endothermic animals. Heat dissipation by evaporation from the body surface. Panting and sweating. Behaviroal responses include animal migration, seeking sun or shadow, and burrowing in mud.