A camel's hump is not full of water - it is full of fat. That stored fat gives the camel energy on long journeys when there is no food to eat. When the fat is used up, the hump goes floppy and small. Once the camel eats and rests again, the hump slowly fills back up. A healthy camel with a full hump can go a week or more without drinking.
Camels have brilliant adaptations for sandy deserts. Their broad, padded feet spread out on soft sand like natural snowshoes so they do not sink. Their nostrils can close almost completely to keep out blowing sand. Their long eyelashes work like a brush to flick sand away from their eyes. Even their lips are tough enough to eat thorny desert plants.
In Sahrawi culture, camels are much more than transport. They provide milk (which is delicious and nutritious), wool from their thick coats, and are the stars of camel racing festivals. Sahrawi families are proud of their camels and give them individual names, just as people in other places name their horses or dogs.