Large animals that inhabit the dese

Large animals that inhabit the desert have evolved a number of adaptations for reducing theeffects of extreme heat. One adaptation is to be light in color, and to reflect rather than absorb theSuns rays. Desert mammals also depart from the normal mammalian practice of maintaining aconstant body temperature. Instead of trying to keep down the body temperature deep inside the body,which would involve the expenditure of water and energy, desert mammals allow their temperatures torise to what would normally be fever height, and temperatures as high as 46 degrees Celsius have beenmeasured in Grants gazelles. The overheated body then cools down during the cold desert night, andindeed the temperature may fall unusually low by dawn, as low as 34 degrees Celsius in the camel.This is an advantage since the heat of the first few hours of daylight is absorbed in warming up thebody, and an excessive buildup of heat does not begin until well into the day.Another strategy of large desert animals is to tolerate the loss of body water to a point that wouldbe fatal for non-adapted animals. The camel can lose up to 30 percent of its body weight as waterwithout harm to itself, whereas human beings die after losing only 12 to 13 percent of their bodyweight. An equally important adaptation is the ability to replenish this water loss at one drink. Desertanimals can drink prodigious volumes in a short time, and camels have been known to imbibe over100 liters in a few minutes. A very dehydrated person, on the other hand, cannot drink enough water torehydrate at one session, because the human stomach is not sufficiently big and because a too rapiddilution of the body fluids causes death from water intoxication. The tolerance of water loss is ofobvious advantage in the desert, as animals do not have to remain near a water hole but can obtainfood from grazing sparse and far-flung pastures. Desert-adapted mammals have the further ability to
3. feed normally when extremely dehydrated, it is a common experience in people that appetite is losteven under conditions of moderate thirst.