You’re never alone. Even when you think you are alone, you’re not. You’re surrounded by lots of small organisms at all times. They’re called microbes.
Most are too small to see without a microscope. Some live in searing heat. Others thrive in freezing cold. Some need oxygen to live, but others do not. Some of these tiny organisms live on you. Some live in you. Others live around you. Let’s take a tour of this mysterious world.
A Closer Look Let’s start with bacteria. Bacteria are among
the simplest forms of life. You are a host to bacteria. Your skin crawls with bacteria. T ey’re in your mouth and nose. Your insides are teeming with them. Your body has so many bacteria, in fact, that
they outnumber your own cells. For every one cell in your body, there are 10 times as many bacterial cells. T at makes you more microbe than human! Before you decide to dive headfirst into a
bottle of hand sanitizer, relax. You need many kinds of bacteria to live. Some bacteria help you digest food. Others fight off sicknesses and keep your skin clean. Less than one percent of bacteria are
harmful to humans. Harmful bacteria can make you sick. One kind of E. coli is a good example. T is type of bacteria can get into foods. Luckily, washing vegetables before cooking them helps. So does cooking meats to the right temperature. Harmful bacteria can also find open doors
into your body. T ey come through open cuts and sores, for example. Once inside, they can make you sick. T ey can cause a sore throat or an earache. Sometimes, you have to take medicines to kill these bacteria.
20 NATIONAL GEOGRAPHIC EXPLORER
E. coli bacteria cover a piece of lettuce.
Skin Deep Some bacteria live in and on you at all times.
Other microscopic creatures just drop by for short visits. Take dust mites, for example. T ey are related to spiders. You may not be able to see them, but they can see you. A crowd of dust mites looks for you every
night when you go to bed. As you snuggle under the covers, the hungry mites lie in wait. It’s not you they want. It’s your skin. On average, you shed 1.5 million dead skin
cells every hour. Dust mites gobble up this dead skin. T ese mites clean up dead skin, and they get a meal. Dust mites can also cause a big problem.
T ey leave behind waste. T is waste builds up. It can cause breathing problems in some people. It can even trigger an asthma attack. Dust mites may not be the only bugs in your
bed. You might find bed bugs, too. T ese little critters are parasites. T ey feed on your blood. You won’t be able to see them as they sneak
up to attack. T ese bugs are small. Still, a bed bug can drink three times its weight in a single feeding. As it drinks, its body swells. T e bug also shoots a fluid into your body. It makes you itch.
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24