A desert is an area that receives fewer than 10 inches of rain annually. The Sahara Desert in northern Africa is the hottest desert in the world and can reach temperatures of 122 degrees Fahrenheit. Not all deserts are hot and dry, however; some are cold, such as the desert in Antarctica. Some deserts are mountainous.
The Sahara is the world's largest desert and changes constantly, growing and shrinking in size. It is home to about 4 million people, who live in areas of Algeria, Libya and Egypt. The Sahara Desert also boasts a massive array of animals, including gazelle, hyena, mongoose, jackal, baboon and more than 300 species of birds. Its several oases are very welcome, particularly by the humans living in the desert.
The Namib Desert has the world's highest desert sand dunes. It is believed to be the oldest desert, sustaining the same hot and dry conditions for about 80 million years. Wildlife manages to survive there, and the Namib is home to the Welwitschia plant, which may live more than 1,000 years. Few large animals live in the Namib Desert, but among those that do are Hartmann's zebra and gemsbok.
The Kalahari Desert is part of a massive sand basin that covers much of central southern Africa. Desert winds shape its sand, but plants stabilize its sand dunes. As well as desert grasses, plant life in the Kalahari includes acacia trees, which can survive for 10 months of one year without water. The desert's animal species are varied and include meerkats, lions and kinds of antelopes.
Because the African deserts are hot and dry, animals and plants living in them must stay as cool as possible and survive with very little water. Camels, for example, store water in their humps and can survive days without eating or drinking. Avoiding sunshine is vital. So some animals live underground, and some other animals move about only at night. Because fresh water is very hard to come by, some plants grow very long roots, whereas others, such as cacti, store water in their fleshy portions.
