Camels are the only animals with a hump. The hump allows a camel to survive an extremely long time (up to two weeks) without food if need be. Because camels typically live in the desert, where food can be scarce for long stretches, this is important.
A camel can carry up to 80 pounds of fat on its back (Baby camels don’t get their humps until they start eating solid food). When a camel consumes the emergency food supply, the hump will shrink and fall to one side. Refueling and a good night’s sleep will return the hump to its upright position.