ADAPTATIONS: It is any attribute of the organism (morphological, physiological, behavioural) that enables the organism to survive and reproduce in its habitat. Many adaptations have evolved over a long evolutionary time and are genetically fixed. 

Physiological adaptation: Even in the absence of water, Kangaroo rat in North American deserts is capable of meeting all its water requirements from its internal fat oxidation in which water is produced as a byproduct. Also it can concentrate its urine. There are various alternatives available to organisms for coping with extremes in their environment like morphological, physiological and behavioural adaptation.