Adaptions in Ectothermic and Endothermic animals to extreme climates
First of all we need to understand what ectothermic and endothermic animals are. Animals differ in their abilities to regulate body temperature (thermoregulation). We sometimes use the terms "cold-blooded" or "warm-blooded." Most reptiles feel cold to the touch, while mammals and birds often feel warm. Somewhat more precise descriptions can be made by using the terms poikilothermic and homoiothermic. The body temperature of poikllotherms is relatively variable, while that of homeotherms is relatively constant. Even more useful terms are Ectothermic or Endothermic, which suggest two different mechanisms of thermoregulation. Ectotherms generally obtain heat from their external surroundings. Their body temperature varies, corresponding at any time with the temperature of their external environment. Endothermic animals, on the other hand, have relatively constant body temperatures. Their body temperature is independent of that of their external environment. Monkeys and walruses, for example, both have body temperatures of about 38"aC, despite living in very different habitats. However if body temperature rises above its optimum level (usually around 40"aC in mammals) then the enzyme rate inside the body will go into
If it gets too hot, it may leave the rock or stand up slightly to allow some air to pass underneath it. In conclusion the animals which exist in the extreme climates of the world have adapted to be able to live well in these habitats and will probably stay living in these habitats for a long time to come. Animals living in cold climates, polar bears and seals for example have a particularly thick layer of sub-cutaneous fat. The humps are stores of flesh and fat that are absorbed as nutrition when food is scarce. If the body temperature is too cold, the thermoregulator stimulates a thyroid secretion, which increases the rate of metabolism. A camel's body temperature can rise by as much as 6"aC to 8"aC to minimize its sweating further aiding in water conservation. What makes the camel survive so well in the desert is its ability to be able to go for many days without water. There is then a general increase in muscle tone, which is then followed by spasmodic contractions (shivering)The response to high temperature is basically the reverse of the above processes; i. If the body temperature decreases dramatically (hypothermia) then this will slow metabolic activity and impairs brain function. They can control their temperature by varying their heartbeat and the rate of the bodies' metabolism. In fact, the body temperatures of lizards may be as much as 40"aC or 50"aC higher than the air temperature. A general increase in the metabolic rate is brought about by the hormones adrenaline and thyroxin which are produced in large amount during cold conditions. If the body temperature continues to drop, the work of internal organs like the liver may be increased and muscle activity in the form of shivering may begin, for muscular activity is the main source of heat available to animals.
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