Large animals that inhabit the dese

Large animals that inhabit the desert have evolved a number of adaptations for reducing the effects of extreme heat. One adaptation is to be light in color, and to reflect rather than absorb the Sun’s rays. Desert mammals also depart from the normal mammalian practice of maintaining a constant 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 to rise to what would normally be fever height, and temperatures as high as 46 degrees Celsius have been measured in Grant’s gazelles. The overheated body then cools down during the cold desert night and indeed 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 the body, 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 would be fatal for non – adapted animals. The camel can lose up to 30 percent of its body weight as water without harm to itself, whereas human beings die after losing only 12 to 13 percent of their body weight. An equally important adaptation is the ability to replenish this water loss at one drink. Desert animals can drink prodigious volumes in a short time, and camels have been known to imbibe over 100 liters in a few minutes. A very dehydrated person, on the other hand, cannot drink enough water to rehydrate at one session, because the human stomach is not sufficiently big because a too rapid dilution of the body fluids causes death from water intoxication. The tolerance of water loss is of obvious advantage in the desert, as animals do not have to remain near a water hole but can obtain food from grazing sparse and far- flung pastures. Desert – adapted mammals have the further ability to feed normally when extremely dehydrated, it is a common experience in people that appetite is lost even under conditions of moderate thirst.

Kết quả (Trung) 3:

居住沙漠的大动物演变了减少的极端热的作用一定数量的适应。一适应是轻的在颜色和反射而不是吸收太阳的光芒。沙漠哺乳动物也离开维护恒定的体温正常哺乳动物的实践。而不是设法控制体温深在身体里面，哪些将介入水开支和能量，沙漠哺乳动物允许他们的温度上升到什么通常是热病高度和的温度，高达46摄氏度在格兰特的瞪羚被测量了。被过度加热的身体然后变冷静在冷的沙漠夜期间，并且温度也许由黎明的确下跌显著地低，一样低象在骆驼的34摄氏度。这是好处，因为最初的少数小时的热白天在使被吸收身体兴奋，并且热过份积累不开始直到天。
大沙漠动物另一个战略是容忍身体水损失对为非适应的动物是致命的点。骆驼能丢失30%的它的体重作为水，不用害处到本身，而人在丢失只12%到13%以后死的他们的体重。同样重要的适应是能力重新补充这水耗在一份饮料。沙漠动物能在短时间内喝巨大的容量，并且骆驼知道在几分钟之内吸取100公升。一个非常被脱水的人，另一方面，不可能喝足够的水重新水化在一个会议，因为人的胃不是十分地大的，因为体液的太迅速稀释导致从水醉的死亡。水耗容忍是明显的好处在沙漠，因为动物不必须在水坑附近保持，但是能得到从吃草稀稀落落和漫长牧场地的食物。沙漠适应的哺乳动物有进一步能力通常哺养，当极端脱水，它是在人的共同的经验胃口甚而在适度干渴的情况下丢失。