Why does a camel have a hump?

There are two kinds of camels, single hump and double hump. The camel’s hump is its unique characteristic and differentiates it from all other animals.

I always thought that the camel stored water in its hump until I saw a documentary on the camel on National Geographic. The camel’s hump is actually not a water reservoir but a giant mound of fat. The camel’s fat gets stored in its hump. The fat in this mound keeps the camel nourished for up to two weeks when it has to go without food.

When the camel needs to use the fat in the hump, the mound becomes flabby and shrinks. If it uses too much the hump flops over to one side. The best part, however, is that once the camels eats some food and gets some rest, the hump will return to its original condition.