Camel

The camel is a cud-chewing mammal of the family Camelidae, order Artiodactyla. It is distinguished from other camelids-the Alpaca, Guanaco, Llama, and Vicuna-by the one or two fal-filled humps on its back. The family arose in North America and, about 10 million years ago, began spreading to other continents. It became extinct in North America itself about 2 million year ago.

Two species of camel now exist; the one-humped dromedary, Camelus dromedarius, and the two-humped Bactrian, C. bactrianus. The dromedary was domesticated more than 5,000 years ago in the Middle East, serving as a means of transport and as a source of milk, meat, wool, hides, and dried manure for fuel. The more docile Bactrian of Central Asia was domesticated about 2,500 years ago.

Adult male dromedaries stand about 2 m (7 ft) at the shoulder and weigh up to 680 kg (1,500 lb). Bactrians are shorter because of shorter legs. The gray to brown coat is short and fine in drodaries, longer in Bactrians. Both species are well adapted to desert life and temperature extremes. Their two-toed feet have spreading, padded toes for walking on sand. When camels move quickly, both legs on the same side of the body advance together, producing a rolling gait.

Camels can obtain enough water from desert vegetation to survive for many months without another water supply. The animals can tolerate water losses equal to 25 percent of their body weight, and they excrete concentrated urine. Other internal modifications enable them to maintain a steady water level in the blood and to drink animals. By having fat localized in a hump, the body is able to lose heat more rapidly. When these fat reserves are called upon, the hump shrinks and tends to sag.

The dromediary, or one-humped camel can be trained to carry heavy loads on long journeys. Adapted to life in the desert, the camel has horny pads on the knees, thigh joints, and chest openings and nostrils for protection from sand and wind.

The Bactrian, or two-humped, camel has shorter legs than the dromedary and is nor able to move as swiftly at its fastest pace. A few wild bands still roam the Gobi.