 Dear students, in this topic we shall discuss evaporative cooling. Evaporation of water causes cooling effect. For many animals it is the most effective means of removing excess body heat. We shall take few examples of animals which use evaporation for cooling purpose. Animals are the animals with naturally moist skin. So water evaporates from their skin and their extra heat is radiated or evaporated. Many reptiles, birds and mammals. Because the faa, they can use their own saliva to keep their surfaces wet or even they urinate on their own selves so that this water may evaporate from their surface and cause cooling. Some vertebrates use the mechanisms of panting and sweating. We shall discuss in detail the mechanisms of sweating and panting. First we discuss sweating which is a mechanism for evaporative cooling. It is present in only those mammals which have sweat glands in their skin. The sweat glands extrude water actively through the pores on to the surface. Sweat glands evaporate from the surface or evaporate from the surface or cause cooling or cause heat loss. Panting is under autonomous control or autonomic control. The students panting involves the use of respiratory system to lose heat by evaporation. Panting occurs in many mammals, birds and few reptiles. In panting a mammal inhales air through the nose but exhalation occurs through the mouth. Panting occurs in nasal cavity through the nose but exhalation occurs in nasal cavity through the mouth. In the process of ventilation, the tongue and other mouth structures are exposed. With this, the breathing rate and depth are increased which is hyperventilation. All these patterns of breathing encourage water evaporation for heat loss. Dear students, the principle of panting is that exhalant air absorbs heat from the lungs. When this heat comes out of nasal cavity then nasal cavity is highly vascularized which retains most of the water and body heat. This is why it is removed from the mouth because mouth is not vascularized and it will not retain water because the water contains heat coming from the respiratory surface so water will not be retained and the water will be lost in the environment which means the vapors which are heat carrying vapors. In this way, in panting the breath is taken through the mouth so that more water is evaporated and the cooling is generated.