The dromedary (Camelus dromedarius) (/ˈdrɒmədɛri/ or /-ədri/), also called the Arabian camel, is a large even-toed ungulate, of the genus Camelus, with one hump on its back.
It is the tallest of the three species of camel; adult males stand 1.8–2 m (5.9–6.6 ft) at the shoulder, while females are 1.7–1.9 m (5.6–6.2 ft) tall. Males typically weigh between 400 and 600 kg (880 and 1,320 lb), and females weigh between 300 and 540 kg (660 and 1,190 lb).
The species' distinctive features include its long, curved neck, narrow chest, a single hump (compared with two on the Bactrian camel and wild Bactrian camel), and long hairs on the throat, shoulders and hump. The coat is generally a shade of brown. The hump, 20 cm (7.9 in) tall or more, is made of fat bound together by fibrous tissue.
Dromedaries are mainly active during daylight hours. They form herds of about 20 individuals, which are led by a dominant male. This camel feeds on foliage and desert vegetation; several adaptations, such as the ability to tolerate losing more than 30% of its total water content, allow it to thrive in its desert habitat. Mating occurs annually and peaks in the rainy season; females bear a single calf after a gestation of 15 months.
The dromedary has not occurred naturally in the wild for nearly 2,000 years. It was probably first domesticated in the Arabian Peninsula about 4,000 years ago, or in Somalia where there are paintings in Laas Geel that figure it from more than 5,000 to 9,000 years ago. In the wild, the dromedary inhabited arid regions, including the Sahara Desert. The domesticated dromedary is generally found in the semi-arid to arid regions of the Old World, mainly in Africa and the Arabian Peninsula, and a significant feral population occurs in Australia. Products of the dromedary, including its meat and milk, support several north Arabian tribes; it is also commonly used for riding and as a beast of burden.
Description & appearance
The dromedary is the tallest of the three camel species. Adult males range in height between 1.8 and 2 m (5.9 and 6.6 ft) at the shoulder; females range between 1.7 and 1.9 m (5.6 and 6.2 ft). Males typically weigh between 400 and 600 kg (880 and 1,320 lb); females range between 300 and 540 kg (660 and 1,190 lb). The distinctive features are its long, curved neck, narrow chest and single hump (the Bactrian camel has two), thick, double-layered eyelashes and bushy eyebrows.They have sharp vision and a good sense of smell. The male has a soft palate (dulaa in Arabic) nearly 18 cm (7.1 in) long, which it inflates to produce a deep pink sac. The palate, which is often mistaken for the tongue, dangles from one side of the mouth and is used to attract females during the mating season. The coat is generally brown but can range from black to nearly white. Leese reported piebald dromedaries in Kordofan and Darfur in Sudan. Piebald coloration in some camels is thought to be caused by the KITW1 allele of the KIT gene, though there is likely at least one other mutation that also causes white spotting. The hair is long and concentrated on the throat, shoulders and the hump. The large eyes are protected by prominent supraorbital ridges; the ears are small and rounded. The hump is at least 20 cm (7.9 in) high. The dromedary has long, powerful legs with two toes on each foot. The feet resemble flat, leathery pads. Like the giraffe, dromedaries moves both legs on one side of the body at the same time.
Compared with the Bactrian camel, the dromedary has a lighter build, longer limbs, shorter hairs, a harder palate and an insignificant or absent ethmoidal fissure. Unlike the camelids of the genus Lama, the dromedary has a hump, and in comparison has a longer tail, smaller ears, squarer feet, and a greater height at the shoulder. The dromedary has four teats instead of the two in the Lama species.
Diet
The dromedary's diet consists mostly of foliage, dry grasses and desert vegetation – mostly thorny plants. A study said the typical diet of the dromedary is dwarf shrubs (47.5%), trees (29.9%), grasses (11.2%), other herbs (0.2%) and vines (11%). The dromedary is primarily a browser; forbs and shrubs comprise 70% of its diet in summer and 90% of its diet in winter. The dromedary may also graze on tall, young, succulent grasses.
In the Sahara, 332 plant species have been recorded as food plants of the dromedary. These include Aristida pungens, Acacia tortilis, Panicum turgidum, Launaea arborescens and Balanites aegyptiaca. The dromedary eats Acacia, Atriplex and Salsola when they are available. Feral dromedaries in Australia prefer Trichodesma zeylanicum and Euphorbia tannensis. In India, dromedaries are fed with forage plants such as Vigna aconitifolia, V. mungo, Cyamopsis tetragonolaba, Melilotus parviflora, Eruca sativa, Trifolium species and Brassica campestris. Dromedaries keep their mouths open while chewing thorny food. They use their lips to grasp the food and chew each bite 40 to 50 times. Its long eyelashes, eyebrows, lockable nostrils, caudal opening of the prepuce and a relatively small vulva help the camel avoid injuries, especially while feeding. They graze for 8–12 hours per day and ruminate for an equal amount of time. Reproduction
Camels have a slow growth rate and reach sexual maturity slower than sheep or goat. The age of sexual maturity varies geographically and depends on the individual, as does the reproductive period. Both sexes might mature by three to five years of age, though successful breeding could take longer. Mating occurs once a year, and peaks in the rainy season. The mating season lasts three to five months, but may last a year for older animals.
During the reproductive season, males splash their urine on their tails and nether regions. To attract females they extrude their soft palate – a trait unique to the dromedary. As the male gurgles, copious quantities of saliva turns to foam and covers the mouth. Males threaten each other for dominance over the female by trying to stand taller than the other, making low noises and a series of head movements including lowering, lifting and bending their necks backward. Males try to defeat other males by biting the opponent's legs and taking the head between his jaws. Copulation begins with foreplay; the male smells the female's genitalia and often bites her there or around her hump. The male forces the female to sit, then grasps her with his forelegs. Camelmen often aid the male insert his penis into the female's vulva. The male dromedary's ability to penetrate the female on his own is disputed, though feral populations in Australia reproduce naturally.Copulation takes from 7 to 35 minutes, averaging 11 to 15 minutes. Normally, three to four ejaculations occur. The semen of a Bikaneri dromedary is white and viscous, with a pH of around 7.8.
A single calf is born after a gestation period of 15 months. Calves move freely by the end of their first day. Nursing and maternal care continue for one to two years. In a study to find whether young could exist on milk substitutes, two male, month-old camels were separated from their mothers and were fed on milk substitutes prepared commercially for lambs, and they grew to normal weights for male calves after 30 days. Lactational yield can vary with species, breed, individual, region, diet, management conditions and lactating stage. The largest quantity of milk is produced during the early period of lactation. The lactation period can vary between nine and eighteen months.
Dromedaries are induced ovulators. Oestrus may be cued by the nutritional status of the camel and the length of day. If mating does not occur, the follicle, which grows during oestrus, usually regresses within a few days. In one study, 35 complete oestrous cycles were observed in five nonpregnant females over 15 months. The cycles were about 28 days long; follicles matured in six days, maintained their size for 13 days, and returned to their original size in eight days.[84] In another study, ovulation could be best induced when the follicle reaches a size of 0.9–1.9 cm (0.35–0.75 in). In another study, pregnancy in females could be recognized as early as 40 to 45 days of gestation by the swelling of the left uterine horn, where 99.5% of pregnancies were located.