Bactrian camel

The Bactrian camel shares the genus Camelus with the dromedary (C. dromedarius) and the wild Bactrian camel (C. ferus). The Bactrian camel belongs to the family Camelidae.[1][5] The ancient Greek philosopher Aristotle was the first European to describe the camels: In his 4th century BCE History of Animals he identified the one-humped Arabian camel and the two-humped Bactrian camel.[6][7] The Bactrian camel was given its current binomial name Camelus bactrianus by Swedish zoologist Carl Linnaeus in his 1758 publication Systema Naturae.[8]

In 2007, Peng Cui (of the Chinese Academy of Sciences) and colleagues carried out a phylogenetic study of the evolutionary relationships between the two tribes of Camelidae: Camelini – consisting of the three Camelus species (the study considered the wild Bactrian camel as a subspecies of the Bactrian camel) – and Lamini – consisting of the alpaca (Vicugna pacos), the guanaco (Lama guanicoe), the llama (L. glama) and the vicuña (V. vicugna). The study revealed that the two tribes had diverged 25 million years ago (early Miocene), notably earlier than what had been previously estimated from North American fossils. Speciation began first in Lamini as the alpaca came into existence 10 million years ago. Nearly 2 million years later, the Bactrian camel and the dromedary emerged as two independent species.[4] However, the fossil record suggests a far more recent divergence between the Bactrian camel and the dromedary because despite a moderately rich fossil record of camelids, no fossil that fits within this divergence is older than middle Pleistocene (about 0.8 Ma).[9]

The Bactrian camel and the dromedary often interbreed to produce fertile offspring. Where the ranges of the two species overlap, such as in northern Punjab, Iran and Afghanistan, the phenotypic differences between them tend to decrease as a result of extensive crossbreeding between them. The fertility of their hybrid has given rise to speculation that the Bactrian camel and the dromedary should be merged into a single species with two varieties.[10] However, a 1994 analysis of the mitochondrial cytochrome b gene revealed that the species display 10.3% divergence in their sequences.[11]

Skeleton

The Bactrian camel is the largest mammal in its native range and is the largest living camel while being shorter at the shoulder than the dromedary. Shoulder height is from 160 to 180 cm (5.2 to 5.9 ft) with the overall height ranging from 230 to 250 cm (7.5 to 8.2 ft),[17][18][19] head-and-body length is 225–350 cm (7.38–11.48 ft), and the tail length is 35–55 cm (14–22 in). At the top of the humps, the average height is 213 cm (6.99 ft).

Detail of feet

Body mass can range from 300 to 1,000 kg (660 to 2,200 lb), with males weighing around 600 kg, and females around 480 kg.[20][2][21] Its long, wooly coat varies in colour from dark brown to sandy beige. A mane and beard of long hair occurs on the neck and throat, with hairs measuring up to 25 cm (9.8 in) long.

The shaggy winter coat is shed extremely rapidly, with huge sections peeling off at once, appearing as if sloppily shorn. The two humps on the back are composed of fat (not water as is sometimes thought). The face is typical of a camelid, being long and somewhat triangular, with a split upper lip. The long eyelashes, along with the sealable nostrils, help to keep out dust in the frequent sandstorms which occur in their natural range. The two broad toes on each foot have undivided soles and are able to spread widely as an adaptation to walking on sand. The feet are very tough, as befits an animal of extreme environments.

These camels are migratory, and their habitat ranges from rocky mountain massifs to flat arid desert, stony plains, and sand dunes. Conditions are extremely harsh – vegetation is sparse, water sources are limited and temperatures are extreme. The coat of the Bactrian camel can withstand cold as low as −30 °C (−22 °F) in winter to 50 °C (122 °F) in summer.[22] The camels' distribution is linked to the availability of water, with large groups congregating near rivers after rain or at the foot of the mountains, where water can be obtained from springs in the summer months, and in the form of snow during the winter.

Petroglyphs of Bactrian camel

Bactrian camels are exceptionally adept at withstanding wide variations in temperature, ranging from freezing cold to blistering heat. They have a remarkable ability to go without water for months at a time, but when water is available they may drink up to 57 liters at once. When well fed, the humps are plump and erect, but as resources decline, the humps shrink and lean to the side. When moving faster than a walking speed, they pace, by stepping forwards with both legs on the same side (as opposed to trotting, using alternate diagonals as done by most other quadrupeds). Speeds of up to 65 kilometres per hour (40 mph) have been recorded, but they rarely move this fast. Bactrian camels are also said to be good swimmers. The sense of sight is well developed and the sense of smell is extremely good. The lifespan of Bactrian camels is estimated at up to 50 years, more often 20 to 40 in captivity.

Diet

Skull

Bactrian camels are diurnal, sleeping in the open at night and foraging for food during the day. They are primarily herbivorous. With tough mouths that can withstand sharp objects such as thorns, they are able to eat plants that are dry, prickly, salty or bitter, and can ingest virtually any kind of vegetation. When other nutrient sources are not available, these camels may feed on carcasses, gnawing on bones, skin, or various different kinds of flesh. In more extreme conditions, they may eat any material they find, which has included rope, sandals, and even tents. Their ability to feed on a wide range of foods allows them to live in areas with sparse vegetation. The first time food is swallowed, it is not fully chewed. The partly masticated food (called cud) goes into the stomach and later is brought back up for further chewing.

Bactrian camels belong to a fairly small group of animals that regularly eat snow to provide their water needs. Animals living above the snowline may have to do this, as snow and ice can be the only forms of water during winter, and by doing so, their range is greatly enlarged. The latent heat of snow and ice is big compared with the heat capacity of water, forcing animals to eat only small amounts at a time.[23]

Reproduction

A mother with a calf

Bactrian camels are induced ovulators – they ovulate after insemination (insertion of semen into the vagina); the seminal plasma, not the spermatozoa, induces ovulation. Ovulation occurs in 87% of females after insemination: 66% ovulate within 36 hours and the rest by 48 hours (the same as natural mating). The least amount of semen required to elicit ovulation is about 1.0 ml.[24]

Males during mating time are often quite violent and may bite, spit, or attempt to sit on other male camels. The age of sexual maturity varies, but is usually reached at 3–5 years. Gestation lasts around 13 months. One or occasionally two calves are produced, and the female can give birth to a new calf every other year. Young Bactrian camels are precocial, being able to stand and run shortly after birth, and are fairly large at an average birth weight of 36 kg (79 lb). They are nursed for about 1.5 years. The young calf stays with its mother for three to five years, until it reaches sexual maturity, and often helps raise subsequent generations for those years. Wild camels sometimes breed with domesticated or feral camels.

The Bactrian Camels Genome Sequencing and Analysis Consortium provides a C. bactrianus ferus genome using next generation sequencing.[25][26]

Two Bactrian camels at the Cotswold Wildlife Park in England

The Bactrian camel was domesticated circa ~4,500 BCE.[27] The dromedary is believed to have been domesticated between 4000 BCE and 2000 BCE in Arabia. As pack animals, these ungulates are virtually unsurpassed, able to carry 170–250 kg (370–550 lb) at a rate of 47 kilometres (29 mi) per day, or 4 kilometres per hour (2.5 mph) over a period of four days.[28] The species was a mainstay of transportation on the Silk Road.[29] Furthermore, Bactrian camels are frequently ridden, especially in desertified areas. In ancient Sindh, for example, Bactrian camels of two humps were initially used by the rich for riding. The camel was later brought to other areas such as Balochistan and Iran for the same purpose.[28]

Camel figures from the tomb of Tang general Liu Tingxun

Bactrian camels have been the focus of artwork throughout history. For example, western foreigners from the Tarim Basin and elsewhere were depicted in numerous ceramic figurines of the Chinese Tang dynasty (618–907).

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  Riding a Bactrian camel in Nubra Valley, India
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  Bactrian camels in Mongolia
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  A Bactrian camel at a farm in Central Mongolia
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  Bactrian camels in the Chuya Steppe, Altai Mountains, Russia
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  Bactrian Camels in the Kyzyl Kum Desert
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  Bactrian Camel on a farm in Vermont, US

• Bactria
• Camel
• List of animals with humps

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Camelus bactrianus (category)

Wikispecies has information related to Camelus bactrianus.

• "Camelus bactrianus". Animal Diversity project. University of Michigan.
• Handwerk, Brian (3 December 2002) [November 2002]. "Wild Bactrian camels critically endangered, group says". National Geographic.
• "Wild camel protection foundation".
• Sneddon, Aaron. Bactrian Camels at the Highland Wildlife Park, Scotland. flickr.com (images).
• "'New' camel lives on salty water". BBC. 6 February 2001. – BBC announces discovery of camels in the Gashun Gobi region