Kangroo Rat

Kangroo rat Dipodornys merriami, a native of South-West America is a classical example of how small mammals survive in desert. It exhibits all the osmoregulatoryadaptations for desert life. It survives in arid conditions without ingesting any free water by the followi.ng adaptations:

1. It avoids much of the daytime heat through nocturnal life-style, keeping cool, during daylight hours by remaining in a burrow. This conserves water loss through evaporative cooling.
2. It conserves respiratory moisture by an efficient nasal countercurrent mechanism.
3. It secretes highly concentrated urine.
4. The rectum absorbs water from the faeces resulting in dry faecal pellets.

Kangroo rat is not known to drink water. It gets only a trace of free water from the dry seeds it eats. Primarily it depends upon the metabolic water for its survival.