Camel

A camel is an even-toed ungulate within the genus Camelus, bearing distinctive fatty deposits known as humps on its back.

There are two species of camels : the dromedary or Arabian camel has a single hump, and the bactrian has two humps.

Dromedaries are native to the dry desert areas of West Asia, and Bactrian camels are native to Central and East Asia. Both species are domesticated, they provide milk and meat, and are working animals.

The average life expectancy of a camel is 40 to 50 years. A fully grown adult camel stands 1.85 m (6ft 1 in) at the shoulder and 2.15 m (7 ft 1 in) at the hump. The hump rises about 30 in (76.20 cm) out of its body. Camels can run at up to 65 km/h (40 mph) in short bursts and sustain speeds of up to 40 km/h (25 mph).

Distribution and Numbers

The 14 million dromedaries alive today are domesticated animals (mostly living in the Horn of Africa, the Sahel, Maghreb, Middle East and South Asia). The Horn reign alone has the largest concentration of camels in the world, where the dromedaries constitute an important part of local nomadic life. They provide peripatetic Somali and Ethiopian people with milk, food and transportation.

The Bactrian camel is now reduced to an estimated 1.4 million animals, mostly domesticated. It is thought that there are about 1,000 wild Bactrian camels in the Gobi Desert in China and Mongolia.

There is a substantial feral population of dromedary camels estimated at up to 1,000,000 in central parts of Australia, descended from individuals introduced as a method of transport in the 19th century and early 20th century. This population is growing at approximately 8% per year. The government of South Australia has recently decided to cull the animals using aerial marksmen, in part because the camels use too much of the limited resources needed by sheep farmers.

A small population of introduced camels, dromedaries and Bactrians survived in the Southwest United States until the second half of the 20th Century. These animals, imported from Turkey, were part of the U.S. Camel Corps experiment and used as draft animals in mines and escaped or were released after the project was terminated. Twenty-three Bactrian camels were brought to Canada during the Cariboo Gold Rush.

Eco-behavioral Adaptations

Camels do not store water in their humps as is commonly believed. The humps are actually a reservoir of fatty tissue. Concentrating body fat in their humps minimizes heat-trapping insulation throughout the rest of their body, which may be an adaptation to living in hot climates. When this tissue is metabolized, it acts as a source of energy, and yields more than 1 g of water for each 1 g of fat converted through reaction with oxygen from air. This process of fat metabolization generates a net loss of water through respiration for the oxygen required to convert the fat.

Their ability to withstand long periods without water is due to a series of physiological adaptations. Their red blood cells have an oval shape, unlike those of other mammals, which are circular. This facilitates their flow in a dehydrated state. These cells are also more stable in order to withstand high osmotic variation without rupturing when drinking large amounts of water (100 litres (22 imp gal; 26 US gal) to 150 litres (33 imp gal; 40 US gal) in one drink. Oval red corpuscles are not found in any other mammal, but are present in reptiles, birds and fish.

Commercial camel market headcount in 2003

Camels are able to withstand changes in body temperature and water consumption that would kill most other animals. Their temperature ranges from 34 °C (93 °F) at night and up to 41 °C        (106 °F) during the day, and only above this threshold will they begin to sweat. The upper body temperature range is often not reached during the day in milder climatic conditions, and therefore, the camel may not sweat at all during the day. Evaporation of their sweat takes place at the skin level, not at the surface of their coat, thereby being very efficient at cooling the body compared to the amount of water lost through perspiration.

A feature of their nostrils is that a large amount of water vapor in their exhalations is trapped and returned to their body fluids, thereby reducing the amount of water lost through respiration. They can withstand at least 20-25% weight loss due to sweating (most mammals can only withstand about 15% dehydration before cardiac failure results from circulatory disturbance). A camel's blood remains hydrated, even though the body fluids are lost, until this 25% limit is reached.

Camels in the Guelta d'Archei, in north-eastern Chad

Camels eating green herbage can ingest sufficient moisture in milder conditions to maintain their bodies hydrated state without the need for drinking. A camel's thick coat reflects sunlight, and also insulates it from the intense heat radiated from desert sand. A shorn camel has to sweat 50% more to avoid overheating. Their long legs help by keeping them further from the hot ground. Camels have been known to swim.

Their mouth is very sturdy, able to chew thorny desert plants. Long eyelashes and ear hairs, together with sealable nostrils, form a barrier against sand. Their gait and their widened feet help them move without sinking into the sand. The kidneys and intestines of a camel are very efficient at retaining water. Urine comes out as a thick syrup, and their feces are so dry that they can fuel fires.

Domesticated camels at the Pyramids of Giza, Egypt.

All camelids have an unusual immune system. In all mammals, the Y-shaped antibody molecules consist of two heavy (or long) chains along the length of the Y, and two light (or short) chains at each tip of the Y. Camels also have antibody molecules that have only two heavy chains, which makes them smaller and more durable. These heavy chain-only antibodies, which were discovered in 1993, probably developed 50 million years ago, after camelids split from ruminants and pigs, according to biochemist Serge Muyldermans.