The two species do interbreed, and interbreeding may have contributed to the development of cold-adapted dromedaries noted earlier. A single hump has a smaller surface area from which to absorb heat and lose water than a double one. Whether one or two, humps have the same function. The fat-filled hump may also slow the conduction of heat from the sun to the delicate internal organs. It s not surprising that so many people believed humps stored water.
Camels can go without drinking water longer than any other domestic animal.
During the cool winter season in the Sahara, for instance, camels get all the water they need from the plants they eat and thus may go six or seven months without drinking. During the summer, camels need drinking water but even at the hottest daytime temperatures in the Sahara, which may exceed 118oF, camels drink only every five days. During each watering bout, however, camels quickly drink huge amounts of water up to 50 gallons in a few hours when they ve gone five to seven days without. Camels can go so long without water because they lose it very slowly and can withstand high rates of dehydration that may result in the loss of more than 30 percent of their body weight. Camels save water by producing dry feces and only small amounts of urine.