Why do organisms adapt?

The elephant is an inhabitant of a hot climate. This is suggested by:

What are the various possibilities seen in different organisms to achieve homeostasis? Discuss.

In summer,when the outside temperature is higher than our body temperature,we sweat profusely. The resulting evaporative cooling,similar to what happens with a desert cooler in operation,brings down the body temperature. In winter,when the temperature is much lower than $37^{\circ}C$,we start to shiver,a kind of exercise which produces heat and raises the body temperature. These organisms are called:

Adaptations of organisms can be related to which of the following?

The flora and fauna in lakes or ponds are known as: