There are many ways in which animals in warm environments regulate their body temperatures to escape death through overheating. Birds and mammals are homeotherms that maintain a relatively steady body temperature through the metabolic generation of heat. Animals that are able to metabolically produce heat are also known as endotherms
Large mammals, such as humans and horses, can cool themselves through the release of sweat. The evaporation of sweat dissipates heat from the body and cools the animal. Some mammals also pant in order to release heat through the evaporation of moisture from the upper respiratory tract and to meet oxygen demands.
Small mammals may seek cool microclimates in the shelter of burrows and rock crevasses when temperatures are too high.
· Too cold
Two primary adaptations exist to cope with cold for birds and mammals that remain active at low temperatures. The first is increased metabolic rates to generate body heat. The second strategy involves increasing insulation to reduce heat losses. Insulation can take the form of fat, fur, or plumage.
· Humidity
Water can be lost directly through evaporation from the skin. Evaporative water loss can be particularly high for animals with permeable skin such as worms or amphibians. Water can also be lost through respiration, excrement, and other secretions.
Water is generally replenished by drinking, and many animals are limited to areas where free water exists in lakes, streams, springs, and as dew on leaves. Water can also be obtained through food and, in the case of some insects, it is directly absorbed through the skin.
In order to avoid water losses through excrement, the rats produce very small quantities of very dry feces and urine which contain very highly concentrated amounts of urea relative to the water content.
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