Tuesday, January 31, 2017
From Wikipedia, the free encyclopedia
A camel is an even-toed ungulate within the genus Camelus, bearing distinctive fatty deposits known as "humps" on its back. The three surviving species of camel are the dromedary, or one-humped camel (C. dromedarius), which inhabits the Middle East and the Horn of Africa; the Bactrian, or two-humped camel (C. bactrianus), which inhabits Central Asia; and the critically endangered wild Bactrian camel (C. ferus) that has limited populations in remote areas of northwest China and Mongolia. Bactrian camels take their name from the historical Bactria region of Central Asia... Both the dromedary and the Bactrian camels have been domesticated; they provide milk, meat, hair for textiles or goods such as felted pouches, and are working animals with tasks ranging from human transport to bearing loads.
The term camel is derived via Latin and Greek (camelus and κάμηλος kamēlos respectively) from Hebrew or Phoenician gāmāl.
Most of the world's camels are dromedaries (94%) while Bactrian camels and wild Bactrian camels make up only 6% of the total camel population ... "Camel" may also be used more broadly to describe any of the seven camel-like mammals in the family Camelidae: the three true camels and the four New World camelids (the llama, alpaca, guanaco, and vicuña).
The average life expectancy of a camel is 40 to 50 years. A full-grown adult camel stands 1.85 m (6 ft 1 in) at the shoulder and 2.15 m (7 ft 1 in) at the hump. 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). Bactrian camels weigh 300 to 1,000 kg (660 to 2,200 lb) and dromedaries 300 to 600 kg (660 to 1,320 lb). For instance, the average speed for the one humped camel is about 40 km/hour while the two humped camel has around 27.2 km/hour.
The male dromedary camel has in its throat an organ called a dulla, a large, inflatable sac he extrudes from his mouth when in rut to assert dominance and attract females. It resembles a long, swollen, pink tongue hanging out of the side of its mouth. Camels mate by having both male and female sitting on the ground, with the male mounting from behind. The male usually ejaculates three or four times within a single mating session. Camelids are the only ungulates to mate in a sitting position.
Camels do not directly store water in their humps as was once commonly believed. The humps are actually reservoirs of fatty tissue: concentrating body fat in their humps minimizes the insulating effect fat would have if distributed over the rest of their bodies, helping camels survive in hot climates. In hot and dry environments, within 8 to 10 days only the dromedary camels might consume water which during this period the third of their body's weight may be reduced due to the dehydration (Breulmann, et al., 2007). When this tissue is metabolized, it yields more than one gram of water for every gram of fat processed. This fat metabolization, while releasing energy, causes water to evaporate from the lungs during respiration (as oxygen is required for the metabolic process): overall, there is a net decrease in water.
Camels have a series of physiological adaptations that allow them to withstand long periods of time without any external source of water. Unlike other mammals, their red blood cells are oval rather than circular in shape. This facilitates the flow of red blood cells during dehydration and makes them better at withstanding high osmotic variation without rupturing when drinking large amounts of water: a 600 kg (1,300 lb) camel can drink 200 L (53 US gal) of water in three minutes.
Camels are able to withstand changes in body temperature and water consumption that would kill most other animals.
Like the horse, before their extinction in their native land, camels spread across the Bering land bridge, moving the opposite direction from the Asian immigration to America, to survive in the Old World and eventually be domesticated and spread globally by humans. Most camels surviving today are domesticated. Along with many other megafauna in North America, the original wild camels were wiped out during the spread of Native Americans from Asia into North America, 12,000 to 10,000 years ago. Although feral populations exist in Australia, India and Kazakhstan, the only wild camels left are the wild Bactrian camels of the Gobi Desert.