Dromedary

The common name "dromedary" comes from the Old French ' or the Late Latin . These originated from the Greek word , (GEN (γενική) ', ), meaning "running" or "runner", used in Greek in the combination (), literally "running camel", to refer to the dromedary. The first recorded use in English of the name "dromedary" occurred in the 14th century. The dromedary possibly originated in Arabia or Somalia, so is sometimes referred to as the Arabian or East African camel. ultimately from a Semitic source akin to Hebrew (') and Arabic ('). ==Taxonomy and classification==

}}}}}}}} The dromedary shares the genus Camelus with the Bactrian camel (C. bactrianus) and the wild Bactrian camel (C. ferus). The dromedary belongs to the family Camelidae. Ancient Greek philosopher Aristotle (fourth century BC) was the first to describe the species of Camelus. He named two species in his History of Animals; the one-humped Arabian camel and the two-humped Bactrian camel. The dromedary was given its current binomial name Camelus dromedarius by Swedish zoologist Carl Linnaeus in his 1758 publication Systema Naturae. In 1927, British veterinarian Arnold Leese classified dromedaries by their basic habitats; the hill camels are small, muscular animals and efficient beasts of burden; the larger plains camels could be further divided into the desert type that can bear light burdens and are apt for riding, and the riverine type – slow animals that can bear heavy burdens; and those intermediate between these two types. 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, which consists of the alpaca (Vicugna pacos), the guanaco (Lama guanicoe), the llama (L. glama), and the vicuña (V. vicugna). The study showed the two tribes had diverged 25 million years ago (early Miocene), earlier than previously estimated from North American fossils. The dromedary and the Bactrian camels often interbreed to produce fertile offspring. Where the ranges of the species overlap, such as in northern Punjab, Persia, and Afghanistan, the phenotypic differences between them tend to decrease as a result of extensive crossbreeding. The fertility of their hybrid has given rise to speculation that the dromedary and the Bactrian camel should be merged into a single species with two varieties. ==Genetics and hybrids==

The dromedary has 74 diploid chromosomes, the same as other camelids. The autosomes consist of five pairs of small to medium-sized metacentrics and submetacentrics. The X chromosome is the largest in the metacentric and submetacentric group. Camel hybridization began in the first millennium BC. For about a thousand years, Bactrian camels and dromedaries have been successfully bred in regions where they are sympatric to form hybrids with either a long, slightly lopsided hump or two humps – one small and one large. These hybrids are larger and stronger than their parents – they can bear greater loads. ==Evolution==

The extinct Protylopus, which occurred in North America during the upper Eocene, is the oldest and the smallest-known camel. During the transition from Pliocene to Pleistocene, several mammals faced extinction. This period marked the successful radiation of the Camelus species, which migrated over the Bering Strait and dispersed widely into Asia, eastern Europe, and Africa. By the Pleistocene, ancestors of the dromedary occurred in the Middle East and northern Africa. The modern dromedary probably evolved in the hotter, arid regions of western Asia from the Bactrian camel, which in turn was closely related to the earliest Old World camels. A jawbone of a dromedary that dated from 8,200 BC was found in Saudi Arabia on the southern coast of the Red Sea. In 1975, Richard Bulliet of Columbia University wrote that the dromedary exists in large numbers in areas from which the Bactrian camel has disappeared; the converse is also true to a great extent. He said this substitution could have taken place because of the heavy dependence on the milk, meat, and wool of the dromedary by Syrian and Arabian nomads, while the Asian people domesticated the Bactrian camel, but did not have to depend upon its products. ==Characteristics==

The dromedary is the tallest of the three camel species. Adult males range in height between at the shoulder; females range between . Males typically weigh between ; They have sharp vision and a good sense of smell. The hair is long and concentrated on the throat, shoulders, and hump. The large eyes are protected by prominent supraorbital ridges; the ears are small and rounded. The hump is at least high. 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. Typically, there are eight sternal and four non-sternal pairs of ribs. The fibula is reduced to a malleolar bone. The dromedary is a digitigrade animal; it walks on its toes, which are known as digits. It lacks the second and fifth digits. The front feet are wide and long; they are larger than the hind feet, which measure wide and long. In the juvenile, the lower first molars develop by 12 to 15 months and the permanent lower incisors appear at 4.5 to 6.5 years of age. All teeth are in use by 8 years. The lenses of the eyes contain crystallin, which constitutes 8 to 13% of the protein present there. The skin is black; the epidermis is thick and the dermis is thick. The hump is composed of fat bound together by fibrous tissue. Each cover hair is associated with an arrector pilli muscle, a hair follicle, a ring of sebaceous glands and a sweat gland. Females have cone-shaped, four-chambered mammary glands that are long with a base diameter of . These glands can produce milk with up to 90% water content even if the mother is at risk of dehydration. The dromedary is the only mammal with oval red blood corpuscles, which facilitates blood flow during dehydration. The lungs lack lobes. Each kidney has a capacity of , and can produce urine with high chloride concentrations. Like the horse, the dromedary has no gall bladder. The grayish violet, crescent-like spleen weighs less than . The triangular, four-chambered liver weighs ; its dimensions are . They are enclosed in a conical bursa and have the dimensions during anestrus. The oviducts are long. The uterus is bicornuate. The vagina is long and has well-developed Bartholin's glands. The penis is covered by a triangular penile sheath that opens backwards; it is about long. The scrotum is located high in the perineum with the testicles in separate sacs. Testicles are long, deep and wide. Health and diseases The dromedary generally suffers from fewer diseases than other domestic livestock such as goats and cattle. Temperature fluctuations occur throughout the day in a healthy dromedary – the temperature falls to its minimum at dawn, rises until sunset and falls during the night. Nervous camels may vomit if they are carelessly handled; this does not always indicate a disorder. Rutting males may develop nausea. Brucellosis is another prominent malady. In an observational study, the seroprevalence of this disease was generally low (2 to 5%) in nomadic or moderately free dromedaries, but it was higher (8 to 15%) in denser populations. Brucellosis is caused by different biotypes of Brucella abortus and B. melitensis. Other internal parasites include Fasciola gigantica (trematode), two types of cestode (tapeworm) and various nematodes (roundworms). Among external parasites, Sarcoptes species cause sarcoptic mange. In another study, dromedaries were found to have natural antibodies against the rinderpest and ovine rinderpest viruses. In 2013, a seroepidemiological study (a study investigating the patterns, causes and effects of a disease on a specific population on the basis of serologic tests) in Egypt was the first to show the dromedary might be a host for the Middle East respiratory syndrome coronavirus (MERS-CoV). A 2013–14 study of dromedaries in Saudi Arabia concluded the unusual genetic stability of MERS-CoV coupled with its high seroprevalence in the dromedary makes this camel a highly probable host for the virus. The full genome sequence of MERS-CoV from dromedaries in this study showed a 99.9% match to the genomes of human clade B MERS-CoV. Another study in Saudi Arabia showed the presence of MERS-CoV in 90% of the evaluated dromedaries and suggested that camels could be the animal source of MERS-CoV. Fleas and ticks are common causes of physical irritation. Hyalomma dromedarii is especially adapted to arid conditions, changing its moulting process to complete more or all of its life cycle on a single host if stressed, and having an unusually wide host range. The larvae are not well understood but their larval questing phase is assumed to occur during the winter, which is also when rain arrives. The nymphs infest the host mostly in January, then the adults May to September. In a study in Egypt, H. dromedarii was dominant in dromedaries, comprising 95.6% of the adult ticks isolated from the camels. Larvae of the camel nasal fly Cephalopsis titillator can cause possibly fatal brain compression and nervous disorders. Illnesses that can affect dromedary productivity are pyogenic diseases and wound infections caused by Corynebacterium and Streptococcus, pulmonary disorders caused by Pasteurella such as hemorrhagic septicemia and Rickettsia species, camelpox, anthrax, and cutaneous necrosis caused by Streptothrix and deficiency of salt in the diet. ==Ecology==

diorama by Jules and Édouard Verreaux Herds may congregate to form associations of hundreds of camels during migrations at the time of natural disasters. The males of the herd prevent female members from interacting with bachelor males by standing or walking between them and sometimes driving the bachelor males away. In Australia, short-term home ranges of feral dromedaries cover ; annual home ranges can spread over several thousand square kilometres. Camels scratch parts of their bodies with their legs or with their lower incisors. They may also rub against tree bark and roll in the sand. and tigers. 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. 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. ==Biology==

Adaptations The dromedary is specially adapted to its desert habitat; these adaptations are aimed at conserving water and regulating body temperature. The bushy eyebrows and the double row of eyelashes prevent sand and dust from entering the eyes during strong windstorms, and shield them from the sun's glare. The dromedary is able to close its nostrils voluntarily; this assists in water conservation. at a rate of per minute. The hump stores up to of fat, which the camel can break down into energy to meet its needs when resources are scarce; the hump also helps dissipate body heat. When this tissue is metabolized, through fat metabolization, it releases energy while causing water to evaporate from the lungs during respiration (as oxygen is required for the metabolic process): overall, there is a net decrease in water. If the hump is small, the animal can show signs of starvation. In a 2005 study, the mean volume of adipose tissues (in the external part of the hump that have cells to store lipids) is related to the dromedary's unique mechanism of food and water storage. In case of starvation, they can even eat fish and bones, and drink brackish and salty water. they are not suitable for walking on slippery and muddy surfaces. 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. Camels are described as atypical seasonal breeders; they exhibit spermatogenesis throughout the whole year with a reduction in spermatogenesis during the nonbreeding season compared to that in the breeding season (Zayed et al., 1995). The breeding season in Egypt is during spring; the spring months. 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. 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. 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. 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. In another study, ovulation could be best induced when the follicle reaches a size of . 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. ==Range==

Its range included hot, arid regions of northern Africa, Ethiopia, the Near East, and western and central Asia. The dromedary typically thrives in areas with a long dry season and a short wet season. They are sensitive to cold and humidity, In the ninth or tenth century BC, the dromedary became popular in the Near East. The Persian invasion of Egypt under Cambyses in 525 BC introduced domesticated camels to the area. The Persian camels were not well-suited to trading or travel over the Sahara; journeys across the desert were made on chariots pulled by horses. The dromedary was introduced into Egypt from south-western Asia (Arabia and Persia). The popularity of dromedaries increased after the Islamic conquest of North Africa. While the invasion was accomplished largely on horseback, new links to the Middle East allowed camels to be imported en masse. These camels were well-suited to long desert journeys and could carry a great deal of cargo, allowing substantial trans-Saharan trade for the first time. In Libya, dromedaries were used for transport and their milk and meat constituted the local diet. mountain range in Iran Dromedaries were also shipped from south-western Asia to Spain, Italy, Turkey, France, Canary Islands, the Americas and Australia. Camels were exported to the Canary Islands in 1405 during the European colonisation of the area, and are still extant there, especially in Lanzarote and to the south of Fuerteventura. Current distribution of captive animals In the early 21st century, the domesticated dromedary is found in the semi-arid to arid regions of the Old World. According to the Yearbook of the Food and Agriculture Organization (FAO) for 1984, eastern Africa had about 10 million dromedaries, the largest population of Africa. Western Africa followed with 2.14 million, while northern Africa had nearly 0.76 million. Populations in Africa increased by 16% from 1994 to 2005. Asia In Asia, nearly 70% of the population occurs in India and Pakistan. The combined population of the dromedary and the Bactrian camel decreased by around 21% between 1994 and 2004. The dromedary is sympatric with the Bactrian camel in Afghanistan, Pakistan, and central and southwestern Asia. India has a dromedary population of less than one million, with most (0.67 million) in the state of Rajasthan. Feral population , near Silverton, New South Wales, Australia. Feral dromedaries are only found in Australia. Feral dromedary populations occur in Australia, where they were introduced in 1840. The total dromedary population in Australia was 500,000 in 2005. Nearly 99% of the populations are feral, and they have an annual growth rate of 10%. ==Relationship with humans==

The strength and docility of the dromedary make it popular as a domesticated animal. Camel urine and camel milk are used for medicinal purposes. Riding camels Market, Yemen Although the role of the camel is diminishing with the advent of technology and modern means of transport, it is still an efficient mode of communication in remote and less-developed areas. The dromedary has been used in warfare since the 6th century BC. It is particularly prized for its capability to outrun horses in the deserts. Record of its use during the time of Alexander the Great indicate that dromedaries could cover up to 50 miles per day for a week and go for up to a month without water. An account by Aurelian also cited that, in his escape to Euphrates, Zenobia used a dromedary to outrun her pursuers after she was defeated at Palmyra. The dromedary also remains popular for racing, particularly in the Arab world. The camels of the Bejas of Sudan and the Hedareb, Bilen, and the Tigre people of Eritrea The ideal age to start training dromedaries for riding is three years, At first the camel's head is controlled, and it is later trained to respond to sitting and standing commands, and to allow mounting. The dromedary can be trained to carry baggage from the age of five years, but must not be given heavy loads before the age of six. The hawia is a typical baggage saddle from Sudan. Camel milk has higher thermal stability compared with cow milk, but it does not compare favourably with sheep milk. Milk yield varies geographically and depends upon the animals' diet and living conditions. The Pakistani dromedary, which is considered a better milker and bigger, can yield when well-fed. Dromedaries in Somalia may be milked between two and four times a day, The acidity of dromedary milk stored at increases at a slower rate than that of cow milk. In 2001, the ability of dromedary milk to form curd was studied; coagulation did not show curd formation, and had a pH of 4.4. It was much different from curd produced from cow milk, and had a fragile, heterogeneous composition probably composed of casein flakes. Nevertheless, cheese and other dairy products can be made from camel milk. A study found bovine calf rennet could be used to coagulate dromedary milk. A special factory has been set up in Nouakchott to pasteurise and make cheese from camel milk. Mystical beliefs surround the use of camel milk in some places; for example, it may be used as an aphrodisiac in Ethiopia. Meat The meat of a five-year-old dromedary has a typical composition of 76% water, 22% protein, 1% fat, and 1% ash. In a study of the fatty acid composition of raw meat taken from the hind legs of seven one-to-three years old males, 51.5% of the fatty acids were saturated, 29.9% mono-unsaturated, and 18.6% polyunsaturated. The major fatty acids in the meat were palmitic acid (26.0%), oleic acid (18.9%) and linoleic acid (12.1%). In the hump, palmitic acid was dominant (34.4%), followed by oleic acid (28.2%), myristic acid (10.3%) and stearic acid (10%). Dromedary slaughter is more difficult than the slaughter of other domestic livestock because of its size and the significant manual work involved. More males than females are slaughtered. Though less affected by mishandling than other livestock, the pre-slaughter handling of the dromedary plays a crucial role in determining the quality of meat obtained; mishandling can often disfigure the hump. The animal is stunned, seated in a crouching position with the head in a caudal position and slaughtered. Dromedaries can be slaughtered between four and ten years of age. As the animal ages, the meat grows tougher and deteriorates in taste and quality. Camel hair, wool and hides Camels in hot climates generally do not develop long coats. Camel hair is light, and has low thermal conductivity and durability, and is thus suitable for manufacturing warm clothes, blankets, tents, and rugs. Hair of highest quality is typically obtained from juvenile or feral camels. In India, camels are clipped usually in spring and around hair is produced per clipping. In colder regions one clipping can yield as much as . A dromedary can produce wool per year, whereas a Bactrian camel has an annual yield of nearly . Dromedaries under the age of two years have a fine undercoat that tends to fall off and should be cropped by hand. Little information about camel hides has been collected but they are usually of inferior quality and are less preferred for manufacturing leather. ==See also==