Desert animals, like desert plants, have adapted in very special ways to live in this hot, dry environment. When finding water is a problem, many animals develop ways of living to help them use less water.
One way to save water is to stay as cool as possible. When people get too hot their bodies start to sweat. This water, coming from small pores in the skin, helps to cool the skin and keeps the body temperature from getting too high. Most desert animals don't sweat, so they have to find other ways of keeping cool.
People are lucky because they can carry water with them in canteens and water bottles. Animals must rely on the water that they can find. Most of the time little water is available, so animals have to be masters at keeping cool and saving water.
Almost all desert animals are smart enough to stay out of the sun during the hottest part of the day. They stay deep underground in burrows. There the sand is much cooler, and burrowing animals, like the kangaroo rat, the badger, the gopher, the coyote and the kit fox, sleep while you are playing on the dunes. At night, after the sun goes down and the sand cools off, the animals come out to hunt for food. When an animal is active at night and rests during the day, it is called nocturnal.
There are a few animals that can be seen during the day. Darkling beetles are crawling about, red-tailed hawks are flying overhead, and you might see a whiptail lizard darting past your feet. These animals, active during the day and inactive at night, are called diurnal. Diurnal animals protect themselves from the heat by spending most of the day in whatever shade they can find.
Because there are no permanent bodies of water in the dune field, most animals get their water solely from the food they eat. Green leaves contain lots of water. The animals that eat only plants, like jackrabbits and gophers, are called herbivores. The body of an animal also contains liquid in its blood and tissues. Animals that eat only other animals are called carnivores. The coyote will eat just about anything, plant or animal. That's what makes him a master at desert survival. Animals that eat both plants and other animals are called omnivores.
The best desert survivor is the kangaroo rat. This little rodent eats only dry seeds, and is never seen drinking water. He is able to make water inside his body while digesting his food. This “metabolic water” is all he needs to survive. He is also a master at saving water. When in his burrow during the day, he seals all the entrances so none of the cool, moist air is lost.
Suppose you are a little brown mouse and you live in the dune field. You don't have long sharp claws, or chemical sprays, or even great speed to save you from being eaten by predators. Even when you wait until dark to go out to hunt for food, your color still makes you stand out against the white sand. Any owl sitting in the treetops can easily see you and swoop down to make you his dinner. You might think an animal like this has no chance to survive, but nature always comes up with a solution.
When a litter of mice is born, they're not all the same color. Some are a little darker, some are a little lighter. When the mice grow up and go into the dunes to hunt for food, which ones do you suppose get gobbled up first? Which ones blend with the color of the sand and are harder for predators to see and catch? If you guessed the dark ones wind up being the meal and the light ones escape, you're right. More of the light ones will survive and have babies with light colored fur.
Because they are better adapted to their environment, because they blend into their surroundings and are less likely to be killed by predators, these lighter-colored animals stand a better chance of survival. This is what is meant by survival of the fittest. You don't have to be the biggest or strongest animal. You just have to be well adapted to your surroundings.
There are two animals living in the dunes that are nearly as white as the sand. They are the Apache pocket mouse and the bleached earless lizard. Their color has changed over many generations to help them survive. This change is called adaptive coloration.