Camel
Dromedary, Camelus dromedarius
Bactrian Camel, Camelus bactrianus
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Artiodactyla
Family:	Camelidae
Tribe:	Camelini
Genus:	Camelus Linnaeus, 1758
range of dromedary and bactrians Camelus bactrianus Camelus dromedarius †Camelus gigas (fossil) †Camelus hesternus (fossil)[verification needed] †Camelus sivalensis (fossil) †Syrian Camel

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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 camel: Dromedary, or one-humped camels, which are native to Arabia and other parts of the Middle East, and Bactrian, or two-humped camels, which live in Central Asia. Both species have been domesticated; they provide milk and meat, and are working animals.

Etymology[link]

The term camel is derived via Latin and Greek from Hebrew or Phoenician gāmāl, possibly from a verb root meaning 'to bear/carry' (related to Arabic jamala).^[1]

Camel is also used more broadly to describe any of the six camel-like creatures in the family camelidae: the two true camels, and the four South American camelids: the llama, alpaca, guanaco, and vicuña.

Biology[link]

The average life expectancy of a camel is 40 to 50 years. A fully grown adult camel stands 1.85 m (6 ft 1 in) at the shoulder and 2.15 m (7 ft 1 in)^{[clarification needed]} at the hump. The hump rises about 75 cm (30 in) 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).

Male dromedary camels have an unusual organ called a dulla in their neck, a large, inflatable sac that he extrudes from his mouth when in rut, to assert dominance and attract females. It appears like a long, swollen, pink tongue hanging out of the side of its mouth.^[2]

Eco-behavioural adaptations[link]

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.^[3] 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.^[4]

A camel's thick coat is one of their many adaptations that aid them in desert-like conditions.

The Horn of Africa has the world's largest population of camels.^[5]

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^[6] 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).^[7] Oval red corpuscles are not found in any other mammal, but are present in reptiles, birds, and fish.^[8]

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.^{[citation needed][9]}

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).^{[citation needed]} A camel's blood remains hydrated, even though the body fluids are lost, until this 25% limit is reached.^{[citation needed]}

Camels are used as draft animals in Pakistan

Camels eating green herbage can ingest sufficient moisture in milder conditions to maintain their bodies' hydrated state without the need for drinking.^[10]

A camel's thick coat 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.^[11]

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.^{[citation needed]}

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.^[12]

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.^[13]

Genetics[link]

Domesticated camels at the Pyramids of Giza, Egypt.

The karyotypes of different camelid species have been studied earlier by many groups,^{[14][15][16][17][18][19]} but no agreement on chromosome nomenclature of camelids has been reached. The most recent study used flow-sorted camel chromosomes building undoubtedly the camel's karyotype (2n=74) that consists of one metacentric, three submetacentric and 32 acrocentric autosomes. The Y is a small metacentric chromosome, while the X is a large metacentric chromosome.^[20]

According to molecular data, the New World and Old World camelids diverged 11 Ma.^[21] In spite of this, these species turned out to be conserved sufficiently to hybridize and produce live offspring(cama).^[22] The dromedary-guanaco inter-specific hybrid provided the ideal platform to compare the karyotypes of Old World and New World camels.^{[citation needed]}

The cama is a camel/llama hybrid bred by scientists who wanted to see how closely related the parent species were. The dromedary is six times the weight of a llama, hence artificial insemination was required to impregnate the llama female (llama male to dromedary female attempts have proven unsuccessful). Though born even smaller than a llama cria, the cama had the short ears and long tail of a camel, no hump and llama-like cloven hooves rather than the dromedary-like pads. At four years old, the cama became sexually mature and attracted to llama and guanaco females. A second cama (female) has since been produced using artificial insemination. Because camels and llamas both have 74 chromosomes, scientists hope that the cama will be fertile. If so, there is potential for increasing size, meat/wool yield and pack/draft ability in South American camels. The cama apparently inherited the poor temperament of both parents as well as demonstrating the relatedness of the New World and Old World camelids.^{[citation needed]}

Dromedary-Bactrian hybrids are called bukhts, are larger than either parent, have a single hump and are good draft camels. The females can be mated back to a Bactrian to produce ¾-bred riding camels. These hybrids are found in Kazakhstan.^[23]

Evolution[link]

Antelope-like ancient camel, stenomylus

Fossil evidence indicates that the ancestors of modern camels evolved in North America during the Palaeogene period (see also Camelops), and later spread to most parts of Asia.

The earliest known camel is called protylopus, living in North America 40 to 50 million years ago (during the Eocene). It was a forest-dwelling creature about the size of a rabbit, but shaped somewhat like a jungle antelope in modern Africa. By 35 million years ago, the poebrotherium had moved to the American savanna, and was the size of a small deer and had many more traits similar to camels and llamas.

After another ten million years, the environment in North America began to change significantly, giving rise to a number of specialized camel ancestors, like the long-necked alticamelus and the fast-running, light stenomylus.

By three million years ago the direct ancestor of all modern camels evolved, procamelus. Within one million years its descendants had moved into South America (where they would eventually become the vicuna, alpaca, and llama) and Asia (where they would become the bactrian and dromedary camels). Not widely-enough separated by genetic drift, these Asian and South American camels can still be artificially crossbred, see cama below.

The last camel native to North America was camelops hesternus, vanishing along with horses, cave bears, mammoths and mastodons, cave lions and sabertooth cats, and most other large animals in North America, coinciding with the immigration of humans from Asia.^[24]

Domestication[link]

A camel with its rider playing kettledrums in the Mughal Empire.

Most camels surviving today are either domesticated, or feral, having only returned to the wild. Along with all other megafauna but bison 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.

Like the horse, before their extinction in their native land, they spread across the 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.

Dromedaries may have first been domesticated by humans in southwestern Arabia, between 6,000 and 3,400 years ago, the bactrian in central Asia 2500 years ago.

The people of ancient Somalia first had domesticated camels well before 2000 BC.^[25][26]

Military uses[link]

British Imperial Camel Corps Brigade in Egypt

By at least 1200 BC, the first camel saddles had appeared, and Bactrian camels could be ridden. The first Arabian saddle was put way to the back of the camel, and control of the Bactrian camel was exercised by means of a stick. However, it wasn't until between 500–100 BC that Bactrian camels finally attained a military use. These new saddles were put over the humps of the animal, and they were also inflexible and bent, dividing the weight sufficiently over the animal. In the seventh century BC, the military Arabian saddle appeared, which improved the saddle design again slightly.^[27]

Camel cavalry have been used in wars throughout Africa, the Middle East and into modern-day Border Security Force of India. Armies have also used camels as freight animals instead of horses and mules.

In the East Roman Empire the Romans used auxiliary forces known as Dromedarii, whom they recruited in desert provinces. The camels were mostly used in combat because of their ability to scare off horses at close ranges, a quality famously employed by the Achaemenid Persians when fighting Lydia, although the Persians usually used camels in baggage trains for arrows and equipment.^{[citation needed]}

19th and 20th centuries[link]

• The United States Army established the U.S. Camel Corps, which was stationed in California in the 19th century. One may still see brick stables at the Benicia Arsenal in Benicia, California, where they nowadays serve as artists' and artisans' studio spaces. During the American Civil War, camels were used at an experimental stage, but were not used any further, as they were unpopular with the men. Some escaped and their descendants roamed the arid parts of the American West until as late as the early 20th century.
• France created a méhariste camel corps as part of the Armée d'Afrique in the Sahara from 1902, replacing regular units of Algerian spahis and tirailleurs earlier used to patrol the desert boundaries. The camel-mounted units remained in service until the end of French rule in 1962. The French transferred the French personnel to other units and disbanded the locally recruited méharistes.
• In 1916, during World War I, the British created the Imperial Camel Corps, which was a brigade-sized military formation that fought in the Sinai and Palestine Campaign. It comprised infantry mounted on camels for movement across desert. In May 1918 the Corps was reduced in strength to a single battalion and was formally disbanded in May 1919. Also during World War I, the British Army created the Egyptian Camel Transport Corps, which consisted of a group of Egyptian camel drivers and their camels. The Corps supported British war operations in the Sinai desert, Palestine and Syria by transporting supplies to the troops.
• The Somaliland Camel Corps was a unit of the British Army based in British Somaliland from the early 20th century until the 1960s.
• The Bikaner Camel Corps was a military unit from India that fought for the Allies in World War I and World War II.
• The Tropas Nómadas (Nomad Troops) were an auxiliary regiment of Sahrawi tribesmen serving in the colonial army in Spanish Sahara (today Western Sahara). Operational from the 1930s until the end of the Spanish presence in the territory in 1975, the Tropas Nómadas were equipped with small arms and led by Spanish officers. The unit guarded outposts and sometimes conducted patrols on camelback.

Food uses[link]

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