Why do deserts have special plants and animals?

Deserts cover about one-fifth of Earth’s surface and occur where rainfall is less than 10 inches (25 centimeters) per year. Most deserts—such as the Sahara of North Africa and the deserts of the southwestern U.S., Mexico, and Australia—occur at low latitudes. Another kind of desert, cold deserts, formed in the basin area of Utah and Nevada and in parts of western Asia. Most deserts grow a large amount of specialized vegetation. Soils are rich in nutrients because they need only water to become very productive and have little or no organic matter. Deserts often have the most “weird weather,” such as occasional fires, cold weather, and sudden, intense rains that cause flooding. There are relatively few large mammals in deserts because most are not able to store sufficient water and withstand the heat, which often reaches 113 degrees Fahrenheit (45 degrees Celsius) in the summer months. Deserts provide little shelter from the Sun for large animals. Mammals are usually small, like the kangaroo rats of North American deserts. Other life that can be seen in the desert includes insects and spiders, such as stinkbugs, ticks, and tarantulas; reptiles such as snakes and lizards; and birds, such as hawks, owls, roadrunners, and woodpeckers, who make their homes in cactuses.