 Dear students, in this topic we shall discuss endothermia in cold environments. The cold inhabitant endotherms evolved temporary and permanent mechanisms to maintain and retain body heat in cold environment. These mechanisms involve anatomical as well as physiological features. For example, development of pillage and plumage, formation of a blubber and vasoconstriction of blood vessels. Dear students, the mammals and birds are insulated through fur and feathers. Furs and feathers lower the specific heat conductance. They reduce convection and dissipation of heat by wind. The hairs and feathers are fluffed. When they are fluffed, they keep or trap the air inside them. This air is warmed by body heat and forms a thick warm layer of, layer around the body that protects the inner heat from getting lost to the environment and also protects the animal from external cold. Dear students, pillage, farky covering, size or its thickness vary with the insulation and needs of the animal which arise from cold and seasonal variations. Arctic animals have very thick cold and during pillage. Temperate animals exhibit seasonal variations. These animals shed their fur or feathers in summer and grow them thicker and thicker. In winter, they are saved from overheating. Dear students, now we shall discuss the role of blubber. Blubber is a thick layer of insulating subcutaneous fat. It is a fat fat that is found under the skin and it is found in a lot of marine mammals like seals, walruses, sirenians or cetaceans, i.e. whales and dolphins. It is a very good insulator because of its low thermal conductivity. Fatty acids metabolically least active and blood vascularization in them is also very low so they prevent heat loss from the body surface. Dear students, diversion of blood flow away from the skin also controls heat loss from the surface. Fat flow is used physiologically to control the mechanism that is vasoconstriction. The blood vessels or arterioles that are taking blood towards the skin are being contracted or constricted so that the warm blood coming from the body surface does not have a lot of perfuse in the cold skin so that heat loss is not there. Because of this mechanism, body conserves heat of the core.