Staying Cool: Hot Desert Animals
The kinds of animals in hot deserts vary greatly, depending on the physical features and plants of the area. Generally there are few or no large mammals living in deserts because they are not able to store water in their bodies and the desert provides little shelter from the hot sun. Most desert animals are nocturnal animals, which means they are active at night. Most stay deep underground in burrows where the sand is much cooler. Burrowing desert animals include the kangaroo rat, the badger, and the gopher. At night, after the sun goes down and the sand cools off, the animals come out to hunt for food. There are a few animals that are active during the day, such as beetles, hawks, and some lizards. But even these animals usually spend most of the day in whatever shade they can find.
The desert tortoise is found in the hot Mojave and Sonoran Deserts. This animal's front legs are muscular and flattened with long claws for digging. Its shell is from 9 to 15 inches (22.5 to 37.5 cm) long and about 4 to 6 inches (10 to 15 cm) high. It weighs about 8 to 15 pounds (3.6 to 6.8 kg). The desert tortoise spends about 95 percent of its life in underground burrows. Some burrows are as deep as 3 feet (0.9 m).
Because there is a lack of other water sources in a desert, some animals get all the water they need from the food they eat. For example, pack rats in hot deserts get water from the juicy plants they eat, such as the cactus. Snakes that eat pack rats, get water from the rat.
The kangaroo rat is another hot desert animal that gets water from the food it eats. This animal can live entirely on dry seeds without ever drinking water. These rats rehydrate (restore moisture) the dry seeds by storing the seeds in their burrows. The air in the burrows is humid, partly from moisture in the rat's exhaled breath. The dry seeds soak up some of the moisture from the air, so the rat gets some of the water from its own body back by eating the moist seeds.
Some animals sleep through especially hot, dry summer periods. This is similar to hibernation and is called estivation (dormant condition of some animals during the summer). Instead of sleeping through the winter, animals that estivate sleep through the hot summer when there is not enough food for them.
Fat (nutrient stored in animals and plants) is a good insulator (material that offers a great resistance to the flow of heat into or out of it). Fat helps to keep heat from leaving the body. In animals that live in cold regions, fat is evenly distributed around their bodies so heat stays in. But some hot desert animals have fat supplies that are concentrated in certain areas of their bodies so that heat escapes more easily from the less fatty areas. For example, camels have most of their fat in their humps, and the fattailed gecko has most of its fat in its tail.
Other body parts, such as large ears, can also help to keep an animals cool. The large ears of some animals, such as jackrabbits and foxes, do more than pick up sound. Air blowing over the large surface area of the ears helps to cool the blood in the ears, thus cooling the animal.