What is in a Camel's Hump?
Contrary to popular belief, a camel's hump contains fat and not water - but by a clever bit of biochemistry, it can turn these fats into water molecules.
What is in a fat?
A fat is a long hydrocarbon chain, wich means it is made up of carbon and hydrogen atoms. This means it contains one of the raw components of water - hydrogen. Oxygen is also widely avaiable as O2 in the atmosphere which camels and humans (and all other mammals) breathe in. If the body was able to break down these fats and turn them into carbon and hydrogen, it may be possible for them to make water.
Can They do it?
Yes they can! The process of respiration, in which Glucose and Oxygen are converted to Carbon Dioxide and Water to produce energy for everything we do is exactly what enables this to occur. It is possible for the body to use substances other than glucose such as fats as a starting point for this process. A fat is a much larger molecule than glucose and so much more oxygen is required to break it up and so there is also a lot more water produced when 1 fat molecule is broken up in comparison to one glucose molecule.
What does this mean?
Creatures that live in places with little water such as deserts or the poles will have high levels of fat to provide them with water as they break it down by respiration. By conserving water loss by other methods including excreting more concreted urine and behaviors that encourage resting in the shade it allows animals such as camels to go for a very long time without a drink.
What about the Cold?
At the poles, all the available water is looked up as ice. Seals which live in the Arctic have a special type of fat called brown fat. This fat serves several purposes. It is very rich in mitochondria and is broken down especially to produce heat which keeps the seal from freezing on the ice. The by-product of this however is water which is produced in very large quantities and provides the seal with water it wouldn’t otherwise have access to, thus keeping it alive.
A Camel by ha-noded on Flickr