Many children believe the hump of a camel may serve as a canteen, providing needed water for the camel that lives in the desert. In actual fact, these children are not completely wrong, for while the hump is made of fat, its primary purpose may, in fact, be to provide water. While fat does not contain water, the breaking down of fat produces water. The reason the camel has the fat stored in a hump is to reduce the insulation it would cause if it was spread evenly under the skin. The fat in the hump can also act as a source of energy, for the breaking down of fat also releases energy and can substitute for food. A floppy hump means that the fat stores are low, and suggest that it is time for the camel to get to an oasis where it can eat more food and drink more water.
Other animals in the desert also store fat to help provide a source of water in times of needs. Desert rodents, such as the jerboa, store fat in their tails as it provides a source for water and energy, causes minimal insulation, and can aid in balance and movement. The observation that desert mammals often have higher amounts of fat is related to their need for water. Even desert ants tend to have more fat (which is not visible since it is inside their hard exoskeleton).
References
- Johnson, R.J., Stenvinkel, P., Jensen, T., Lanaspa, M.A., Roncal, C., Song, Z., Bankir, L. and Sanchez-Lozada, L.G. (2016) Metabolic and Kidney Diseases in the Setting of Climate Change, Water Shortage, and Survival Factors. J Am Soc Nephrol 27: 2247-2256.