What does a camel store in its humps?

You have no doubt heard stories about the wonderful endurance of camels plodding through the desert for days without a drink, living on the water stored in their humps. The claims for the camel’s endurance are often exaggerated but it is true that this animal can survive for several days without taking water. However, the camel does not fill its hump with water before it starts such a journey, rather as you might fill a car’s tank with petrol. The humps are composed of fatty tissues which break down to give energy during periods when the camel is without sufficient food. Water is stored by the camel in its tissues and it draws on this supply as it plods along. After a long journey the camel is usually very thin and dried up and it takes an enormous drink as soon as it can, to make up the loss. It drinks over 20 gallons of water in ten minutes.