The oldest known camel is Protylopus, appeared 40-50 million years ago (Eocene) in North America. It had the size of a rabbit and lived in forests. Later, camels spread to the savannah and increased their size. In Oligocene, 35 million years ago, Poebrotherium had the size of a roe deer, but already resembled a camel. ……………………………………………………………………………………

There are 17 million camels worldwide. 90 % are dromedaries or Arabian camels (with one hump) and 75 % of the dromedaries are found in North/East Africa. 50 % of the world’s dromaderies are found in Sudan and Somalia, in semi-desert areas. 15-20,000 bewildered dromaderies roam western and central Australia.
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Camels are gregarious and well adapted to their environment, the desert. They can carry heavy cargoes, stand sand storms and large temperature differences. Camels are called the “desert ships”, and they can swim when they encounter water. The north Egyptian Lake Borollos has a depth varying between 20 cm and 2 m (0.6 to 6 ft). It cannot be crossed by boat or vehicles, and only camels can be used in this case.
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A camel can resist 17 days without drinking under a scorching heat. It was wrongly believed its resistance resided in the water kept in the hump or in a stomach pouch. If it doesn’t drinking anything for 17 days, a camel can lose a third of its weight, without being affected. But when it catches the opportunity, in can drink 104 litres of water at once (the Bactrian Camel, which is larger, can drink up to 120 litres), in 7-8 minutes! But three days later, there is no sign of water in its stomach or hump.
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To resist the lack of water, the camels have several means of adjusting to the situation. Their body temperature varies depending on the environment: in the cooler morning is of 34o C, whereas during the hot afternoon it goes up to 40-41o C. The kidneys’ function is regulated depending on the water availability: they produce 7 litres of urine when water is abundant, and 500 g when it does not drink for days. When thirsty, transpiration is reduced towards zero.
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A camel’s thick coat maintains an insulating layer, and it also reflects sunlight. A shorn camel has to sweat 50% more to avoid overheating. It also insulates them from the intense heat that radiates from hot desert sand. Their long legs help by keeping them further from the hot ground.
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This ability to fluctuate body temperature and the efficiency of their sweating allows them to preserve about five litres of water a day.
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The rest of the camel’s body is adapted to the conditions in the desert: the hoof is perfect for the soft, instable sand, and the digits are wrapped in an elastic tissue that isolates the foot from the hot ground (while impeding deepening in the sand); the thick eyebrows and eyelashes protect the eyes against sand and sun; the nostrils are moved by muscles that can close them hermetically at will and the ears are filled of hairs that impede the sand to get in. This helps them retain expiration water and protects the animal during the sand storms. Horny layers on the chest, elbows and knees protect the camels against the scorching heat and insect.
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Another issue: camels never run, they just speed up, in their typical gait of moving simultaneously the feet of the same part of the body. Running would raise transpiration. They can make daily 160 km (100 miles) with a speed of 16 km (10 mi)/hour. In caravans, they make 30-40 km (18-25 ml) per day, with an average age of 3.5 km (2.2 mi) per hour. The maximum speed achieved by a camel is 25 km (16 mi) per hour, but they get tired quickly.
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The camels’ humps are reservoirs of fatty tissue. A full hump has 10-15 kg (22-33 pounds). When this fat is metabolised, it is not only a source of energy, but yields through reaction with oxygen from the air 1,111 g of water per 1,000 g of fat converted.
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After drinking, water is spread uniformly in the body and it is lost gradually, about 100 liters in 17 days. The average water content of the camel’s body is low: while the cow’s tissues contain 80 % water, the donkey’s (another desert animal) 65 %, and the camel’s just 50 %. A camel crossing a desert loses in 24 hours only 2 % of its bodyweight, while the donkey at least 8 %. Curiously, wild Bactrian Camels from the Gobi desert (China-Mongolia) can drink saltwater.
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Camels can withstand at least 20-25% weight loss due to sweating (most mammals can only withstand about 3-4% dehydration before cardiac failure due to the thickened blood).
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But how can camels drink over 100 litres of water at once without serious consequences? This is the same as a human drinking 20 litres of water in 10 minutes. This would induce water intoxication in us. The red blood cells of the camels (and lamas, too) have an ovoid shape and the property of swelling round, till achieving a double volume and after that gradually release the stored liquid. The red blood cells are extremely small and numerous (132.5 million per cubic millimetre).
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In their native lands, camels feel by far the presence of a fountain or river. They never forget the place where they have found water.
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Camels walk 3 km (1.8 mi) per day looking for food, on average 3 hours, and disperse when food is scarce. They require 10-20 kg (22-44 pounds) of fresh food daily (or 5-10 kg (12-24 pounds) of dry food), depending on the animal’s size. If working, the food requirement is of 30-50 kg (70-110 pounds) per day. They spend 8-12 hours per day eating.
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