THE EARTHWORM G3sr04

 4. THE EARTHWORM

Some 2,000 kinds of earthworm wiggle across our world. One giant kind is 12 feet long. One tiny wonder glows like a lantern. Another kind protects itself by shooting out a stinging spray. But the real wonder is the four-inch earthworm most of us know.

If you have gone fishing with worms for bait, you have probably cut an earthworm in two. You may think that he becomes two worms. The chances are against that. But if you pinch off his head or tail, he will probably grow a new one. And if you cut him exactly in half, the head half usually can grow a new tail. The other half often does not have enough food to keep it alive during the three weeks it takes to grow a new head.

The earthworm's body is made up of about 120 ringlike parts. On each of them, except the first and last, are bristles, which keep the worm from slipping as he glides along.

Does the earthworm have a heart? Yes, but not just one. He has four pairs of hearts!

The earthworm has a mouth but no eyes or ears. Still, he can sense the faint light of dawn or the hop of a robin. If he's lucky, the worm will get back to his burrow before the robin catches him.

The earthworm has no lungs. He breathes through his skin, taking oxygen from the air. Underground, he gets oxygen from air spaces in the soil. When water fills up the air spaces, he must come to the surface or drown. That's why we are most likely to see worms after a heavy rain. When it's very dry or warm, the earthworm goes deep underground. There he curls up in a ball in an air space and goes to sleep.

The earthworm spends much of his time burrowing into the earth. But he doesn't dig the way most animals do. He doesn't push the earth aside. Instead he eats it In 24 hours he eats his own weight in leaves, grass and earth. He has been known to dig as far down as eight feet.

Everyone knows that worms are good for catching fish. But do you know that worms are good for plants and for the soil itself? That's really why earthworms can be called wonders.

The tunnels dug out by the earthworm allow air from the surface to enter the soil. The air spaces give plants more room to spread their roots. The worm's tunnels are passages for water too. The soil drains better, thanks to the earthworm.

The earthworm's eating habits improve the soil in other ways. He comes out of his burrow to look for food. And he nibbles at anything from dead insects to dry leaves. He drags leaves into his burrow to eat later. The leaves and other vegetable matter the worm brings underground help to make the soil richer.

The earthworm also brings chemicals from underground to the surface. He eats the soil that holds these chemicals. Then he goes to the surface and deposits the waste from food that has gone through his body. These deposits look like dirt and they are dirt. But in passing through the earthworm's body the chemicals in the soil are changed into a form that plants can use.

In winter the earthworm burrows deep, where the ground does not freeze. There he joins other earthworms. Forming a huge ball, hundreds of them squeeze together. In this way they keep their skins from drying out. When the ground begins to thaw, they all separate and move upward.

The earthworm may live as long as six years. And all that time he is working wonders underground.