Adaptations of endotherms to the cold and hot environment.

Adaptations of endotherms to the cold environment.

• The animals develop large volume to surface ratio. i.e. the extremities such as ear tend to be small and the animals tend to be larger.
• Animals in cold environments have thicker subcutaneous fat.
• Animals in cold environments tend to have heavy fur or hairs.
• Animals in cold environment develop high metabolic rates.
• Reduced extremities to reduce the surface area for heat loss.
• Animals in cold environments develop arteries and veins in close proximity, such that as blood flows down the arteries, heat energy passes from it to the much cooler blood which is returning in the opposite direction in the veins.  The counter-current heat exchange system is seen in flippers of dolphins and the legs of ducks, both of which highly happen to be in cold water.  It achieves two things.  First, it means that the arterial blood has already been cooled by the time it reaches the end of the limb so that relatively little heat energy is lost to the surrounding.  Secondly, it warms the venous blood before it gets back to the main part of the body.

Adaptations of endotherms to Hot environment.

1. Have thin subcutaneous fat layer to promote heat loss
2. Are small compared to their counterpart in cold regions to provide big surface area to volume ratio
3. Have large extremities to increase the surface area for heat loss.
4. They have many sweat glands to produce sweat whose evaporation cools the body
5. Have less fur

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