Ships of the desert
Camels were domesticated more than 3,000 years ago, and to this day, humans depend on them for transport across arid environments. They can easily carry an extra 200 pounds (90 kilograms) while walking 20 miles (32 kilometers) a day in the harsh desert. Camels can travel as fast as horses but can also endure legendary periods of time without food or water. Humans have used camels for their wool, milk, meat, leather, and even dung, which can be used for fuel.
The dromedary camel, also known as the Arabian camel, exists today only as a domesticated animal. About 90 percent of the world’s camels are dromedaries. There are two types of Bactrian camels: one wild and one domesticated. Wild Bactrian camels are much different from domesticated Bactrians: they are trimmer, with smaller humps and less hair.
The dromedary camel has one hump and the Bactrian camel has two. What’s the easiest way to remember? Think of the capital letter D lying on its side: “D” stands for dromedary. Now think of the capital letter B on its side: “B” for Bactrian! But what’s in those humps? They store fat, not water. The fat becomes an energy source.
The length of time a camel can survive on this stored energy depends on climate and the animal’s activity levels. The size of the hump can change, depending on the amount of food the camel eats. When food is scarce, the camel’s body uses the fat stored in the hump, causing the hump to lean over and droop. A camel can go a week or more without water, and it can last for several months without food. It can survive a 40 percent body weight loss and then drink up to 32 gallons (145 liters) of water at one drinking session!