When properly rested and watered, a camel can easily survive a journey without water for three days, and in cool weather it can live without water for as long as a month by feeding on succulent vegetation. Contrary to popular belief, however, the camel goes without water only when forced to do so or if its food contains sufficient water for its needs.
It was once believed that the camel stored water in the hump and drew upon its store when it could not obtain water to drink. Although some water is obtained when fat stored in the hump is used as food, water itself is not stored there. Actually the camel’s ability to go for long periods without water is largely due to three unusual means of adaptation that it possesses.
First, if a camel is forced to go without water, it conserves water by excreting less water in its urine.
Second, most other mammals cannot function well if their body temperatures rise much higher than 100° Fahrenheit. Their temperatures are kept from rising too high by perspiration and by the evaporation of water through air exhaled from the lungs. This cooling process causes the loss of relatively large amounts of water from the body. The camel, however, has a wide range of normal body temperatures and does not begin to sweat freely until its body temperature reaches 105° Fahrenheit. As a result, the camel is able to conserve much water on long desert trips.
Third, when most mammals are forced to go without water, their blood gradually becomes thicker as a result of losing water through perspiration. When the blood becomes so thick that no more water is available for perspiration, fatal overheating may result.
In the camel, however, much of the water lost from the blood is replaced by water drawn from other body tissues. As a result, the normal blood volume can be maintained and the cooling process can continue to function much longer. A man would probably die if he lost water amounting to 12 percent of his body weight, but a camel may survive the loss of water amounting to more than 25 percent of its weight.