How do desert animals keep from drying out?

Have you ever felt your lips get dry and your mouth feel thirsty after playing outside on a hot, sunny day? You wanted a big cool drink of water right away.

Now picture a desert, with warm sand all around and almost no rain for months. Small animals live there, like the kangaroo rat, a tiny animal that hops on two big back feet. So how do desert animals keep from drying out?

Every animal's body is full of water, and heat makes that water leave. When a body gets hot, water slips out through the skin and floats away in each warm breath. Out in the desert sun, a small animal would lose its water fast.

That is why many desert animals dig a burrow, which is a tunnel home under the ground. Down there, the sand above blocks the sun's heat, so the burrow stays cool. A cool body lets out much less water.

The air inside a burrow is damp, too, a little like the air in a bathroom after a warm bath. When an animal breathes that damp air, each breath carries away less water.

Many desert animals sleep in their burrows all through the hot day. When the sun goes down and the sand cools, they creep out to find food. The cool night air takes far less water from their bodies than the hot sun. Fennec foxes, jerboas and kangaroo rats all wait for the night.

Staying out of the sun saves a lot of water, but there is one more way water leaves a body. Every animal pees, and pee carries away waste the body does not need, along with water. What do you think a desert animal's body does to keep from wasting that water?

Inside its body, a desert animal has kidneys, which are two small bean-shaped parts that clean the blood and make the pee. A kangaroo rat's kidneys are amazing at pulling water back into the body before the pee comes out.

So the kangaroo rat makes only a few drops of thick pee. With kidneys like these, very little water leaves its body in pee. Your own kidneys do this job too, just not as strongly.

Burrow. Kidneys. The hot sun pulls water out of bodies, so desert animals rest in a cool, damp burrow through the day, and their kidneys save water by making only a little pee.

Sleep well tonight, snug and cozy, like a kangaroo rat curled up in its cool little home under the sand.