The hump is not full of water - it is full of fat. When food is scarce, the camel slowly uses up the fat and the hump goes a bit floppy. Once the camel eats well again, the hump fattens back up. So a healthy camel has a tall, upright hump.
Camels can drink up to 100 litres of water in 10 minutes - more than five big buckets. Then they can go for over a week in the desert heat without another drink. Their bodies are amazing at saving every drop of water, even from their breath.
Their feet are built for sand. Each foot has two big toes joined by a wide leathery pad that spreads out as the camel steps - like built-in snowshoes. That stops them sinking into soft sand. They walk with both legs on one side at the same time, which makes them rock gently like a boat - one reason their riders call them ships.
Camels are still vital to many Saharan families. The Tuareg people, who live across the southern Algerian desert, have been camel herders for over 1,000 years. Their long camel caravans used to carry salt, dates and silk across the Sahara on journeys that lasted weeks.