The camel’s best known feature is the hump on its back.  The camel’s hump is mostly fat that provides nourishment when food is hard to find.  When a camel goes a long time without food, its hump shrinks.  After it has eaten and rested, its hump becomes plump and firm again.

People once believed that a camel stores water in its hump.  Now we know that a camel simply conserves its body moisture, rather storing an extra water supply.  It can travel for days without food or water because of its fatty hump and its efficient water conservation. – Dick Rogers