Are a Camel’s Humps Full of Water?

Camels are known for being able to go for long periods without drinking a single drop of water. This capacity is often explained by its humps, which supposedly act as water storage tanks. It’s a very desirable ability in desert climates. But is it really all in the humps? Let’s ask the Rumor Detector…

 Laurie Noreau – The Rumor Detector – Agence Science-Presse

A camel’s humps play a vital role for this mammal. But its humps don’t keep it hydrated: the humps contain not water, but fat. This gives it great energy reserves if there’s no food to be had – which can be very useful in a desert climate.

A camel can survive for four to five months without eating. As it uses up its reserves, its humps start to “deflate,” and it has to find food quickly. Note that the one-humped camel, the dromedary, has the same storage capacity as a two-humped Bactrian camel.  

Hydration Champions

Even if the humps don’t keep it hydrated, a camel can go for a week without drinking. Two mechanisms are in play to accomplish this tour de force.

First of all, its red blood cells are oval in shape. This particular configuration permits its blood cells to transport oxygen through thickened blood – a result of dehydration – and circulate in small blood vessels despite the blood’s increased viscosity. But above all, these oval red blood cells can absorb more water. They can inflate to up to 240% of their initial volume without exploding, whereas the blood cells of most species can only inflate to 150% their original size.

All that explains how it is that when a camel finds a water source, it can drink up to 114 litres. That’s the equivalent of a half-filled bathtub!

As well, the camel makes full use of each of its breaths. Its muzzle acts like an air conditioner: its nasal passages remove the humidity from the air it inhales. The air it exhales is therefore drier. The humidity it conserves allows it to stay hydrated just a little while longer as it looks for the next water source.

Camels in Canada’s North  

Surprise: There were camels in the Canadian Arctic 3 ½ million years ago, according to a 2013 discovery made by a team of Canadian researchers. In fact, the camel’s ancestors first appeared in North America 45 million years ago. They migrated to Asia using the Bering Strait land bridge that united North America with Asia. Their famous humps would have helped them even then: the fat reserves on their back would have helped them survive the rude northern winters.    

We can always ask why there’s an accumulation of fat on the back rather than on the abdomen, as there is with a majority of mammals, including humans. One hypothesis is that these back humps fulfil a protective role by exposing the animal less directly to the desert’s hot rays of sunlight. The humps thereby serve to regulate the camel’s body temperature.

French version on the Reflet de Société website

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