Camels store fat in humps—not water tanks on their backs
Camels (genus Camelus) are even-toed ungulates famous for fatty humps, long domesticated across deserts. Adults may live forty to fifty years; a dromedary stands about 1.85 m at the shoulder and 2.15 m at the hump, with Bactrians a foot taller, and bursts near 65 km/h. Informal “camel” talk sometimes sweeps in llamas and other camelids.
Three camel species survive. The one-humped dromedary accounts for 94 percent of all camels and the domestic two-humped Bactrian for 6 percent, while the wild Bactrian is a separate, endangered species of about 1,000 animals, not the ancestor of the domestic form. Loosely, camel can also cover the llama, alpaca, guanaco and vicuña. The whole family arose in North America during the Eocene, and the forerunner Paracamelus crossed the Bering land bridge into Asia around six million years ago.
The hump holds fat, a store of calories, not water. Burning that fat does release water, but the breathing needed to supply oxygen loses more through the lungs, so in dry air the balance is negative. A dromedary can go ten days between drinks in great heat, then take in about 140 litres at once, carried in the bloodstream. It can survive losing a quarter of its body weight in water, when most mammals fail at about 12 to 14 percent.
Other tricks help. Oval red blood cells keep flowing when the blood thickens and resist bursting when the animal drinks heavily. Body temperature drifts from 34 °C at dawn to 40 °C by sunset instead of being held steady with sweat, and a mesh of closely packed vessels cools blood bound for the brain. A camel loses about 1.3 litres of fluid a day, against 20 to 40 for other livestock.
Bactrians weigh up to 1,000 kg, dromedaries up to 600. Camels can sprint at 65 km/h and hold 40 km/h, and they are the only hoofed animals that mate sitting down.
Source: Camel
