Camels can live in the desert for two or three weeks, eating dry food and drinking no water. At the end of that time, a thirsty camel will guzzle enough to fill a bathtub. People used to think that the camel's hump was a sort of natural canteen where the water was stored. But scientists have found that the hump contains fat, not water. A camel lives on this fat when it can't find food in the desert.
Then how can a camel go so long without drinking? The answer is that a camel stores water all over its body — in the flesh and blood and skin and muscles. As it uses the water, its body gets drier and drier. If other animals dry out like this, they get sick. But it doesn't bother the camel at all. In fact, a camel never takes little drinks. It always waits until it is so dry it needs about a bathtub full of water.