The Wonder in Water

Diane Swanson is the author of more than 60 factual books for kids in which she's explored everything from stomachs to science itself. She lives in Victoria.

Salty Sweat

Right this second, sweat is oozing out from glands inside your skin. You have more than 2 million of them all over your body. Like everyone else, you are ALWAYS sweating, even when you don't know you are.

Your sweat is mostly water. So is your blood. In fact, when you were born, your body was nine-tenths water, and you'll still be mainly water when you're grown! Sweat water also contains salt, and some of it has other nutrients, too, such as proteins.

You're lucky that you ooze sweat. It helps to cool you down as it dries on your skin. And it feeds and waters the masses of bacteria -- one-celled life forms, or microbes -- that live on you. If you peer at your skin through a powerful microscope, you can spot them everywhere. There are about 100,000 on a patch hardly bigger than your smallest fingernail. These bacteria crowd out nasty microbes, keeping them from settling on you and making you sick.

Now and then, little visitors ladybugs, sweat bees, moths, and butterflies might land on your skin and dine on the water and salt in your sweat. Some of these insects also feed by sucking sweat out of your tossed-aside T-shirts and sneakers!

From salty sweat to salty seas, there's enough water on this planet to fill 325 million trillion large milk jugs! Some of that water is inside groceries, plants, and animals like you, but almost all of it -- about 98 percent -- sits in the oceans. Another 1.5 percent is frozen, especially as thick ice at Earth's poles and as mountain glaciers, which are masses of year-round snow and ice. The remaining water makes up the world's clouds, rain, puddles, wetlands, rivers, and lakes.

But whatever form water takes, it supports life right around the planet. Not only does it supply food and moisture, it provides shelter, protection, even transportation. Life as you know it cannot exist without water.

Killer Sweat

Sweat water isn't healthy for everything that tries to settle on skin. In fact, it contains an ingredient that's deadly! This ingredient can kill some of the microbes that try to sneak into cuts and infect you -- without bothering the good bacteria.

Having killer sweat is great for you, but it's even better for a hippopotamus. This big African beast often gets scratched and wounded in fights, but its sticky red sweat helps destroy disease-causing bacteria. What's more, the sweat is a sunscreen, keeping the almost hairless hippo from burning.