Camels are iconic desert animals. Their natural adaptations make them perfectly suited to some of the world’s most extreme environments, and their long history as working animals makes them easily recognizable to people around the world. Economies have been built on the humpedbacks of camels traveling the deserts of the world, carrying goods and travelers along with them.
Camels have developed some adaptations to cope with the harsh extremes in the desert. Their eyes have three eyelids, including a transparent one, to keep dust and sand out. They also have two sets of extra-long eyelashesfor the same reason. In a sandstorm, camels can even close their nostrils.
Another surprising fact is that camels’ mouths are lined with papillae, which help prevent mouth injuries while they are gnawing on cactus. And while doing so, the liningalso helps the spinesslide down their throat vertically to the stomach.
Being in such dry, desolateenvironments, camels also have a special relationship with food and water. They can go long periods without eating or drinking thanks to their unique humps. A camel’s hump is almost entirely fat storage, though these fat deposits also contain quite a lot of water. And why is all the fat stored in the hump? Mostly, it’s because having fat throughout the body would increase chances of overheating. So instead, it’s all in just one place.
And though a camel can go long stretches without food or water, they will make up for lost time when they find a source of either calories or moisture. In fact, a full-grown camel can drink 113 litersof water in just 13 minutes, and they recover from dehydration faster than any other mammal.
1. How have camels affected economies in the past?
(A) Their humps have special medical properties.
(B) They worked on farms in hostile environments.
(C) They were transportation for people and merchandise.
(D) They were raised to pick cactus and other thornyfruits.
2. Which of the following is an adaptation camels have developed to deal with sand and dust?
(A) Fat-filled humps.
(B) Nostrils that can close.
(C) Enormous water storage capacity.
(D) Ability to go without eating for a long time.
3. What does “while doing so” refer to in the third paragraph?
(A) When the papillae work.
(B) When camels chew cactus.
(C) When the cactus spines are swallowed.
(D) When camels digest thorns in their stomach.
4. If the following sentences were to be included in the passage, in which paragraph should they be placed?
Also in regard to humps, camels have either one hump or two. Single-humped camels are called Dromedary, while two-humped camels are called Bactrian camels.
