They're squiggly. They're crawly. But while earthworms may seem unimportant and slimy, without them the world would be a much emptier place. Earthworms, billions of them, make the planet's soil fertile enough for plants to grow.
Some Russians believe that if more people knew how interesting and useful worms are, they would treat them better. So in June, the Russians opened a small museum about earthworms here in Moscow.
"Worms are a lot like us," says Yulia Sayapina, a scientist and worm fan who organized the museum. "They're capable of emotions, of suffering and happiness."
Well, maybe. But the museum certainly shows that worms are more complex and mysterious than anyone might think. For starters, there's not just one animal called the earthworm. No one knows exactly how many kinds of earthworms there are, but scientists think there may be about 8,000 species around the world. They range from one millimeter (1/25 in.) long to foot-long night crawlers to the 3-meter-long (12 ft.) giant earthworm of Australia.
Dating back to the dinosaurs
Earthworms, in all their different forms, have been around for about 120 million years. Worms are invertebrates (in-VER-tuh-brits), which means they don't have backbones. They crawl by pushing themselves forward with their tails.
Their daily lives help ours. Basically, earthworms eat anything that rots. That includes vegetables, leaves, grass, and animal dung. They also eat soil. When they digest, earthworms secrete liquids that break down their food. The liquid mixes with minerals from the soil they've eaten. Then everything passes out of the worms' bodies as small balls of soil. Those balls have lots of nutrients that help plants grow. Worm tunnels also help air and water reach plant roots.
But it's not as if earthworms eat whatever is in front of them. They don't have eyes, but they do have advanced senses of touch and smell. Using those senses, they can tell what's edible and what isn't.
That's also how worms build the system of tunnels where they live.
Building a home by eating
They make them by eating the soil they want to go through. The tunnels don't cave in, because the little balls of soil the worms pass are covered with a slime that acts like glue. That keeps the walls of the hole together.
When a night crawler comes out of its hole, it holds onto the inside of the burrow with its tail. Then it searches for food and for a roof for its hole. The roof might be pine needles, leaves, nutshells, berries, even garbage. The worm can move something that weighs 15 to 20 times more than it does. It drags what it has chosen as the roof to the mouth of its hole and pulls it in. The openings of worms' holes look like little dried bouquets of leaves. It also pulls leaves into its hole for dinner. Later, it returns the hard-to-digest leaf stems to the surface.
The worms go to all this trouble to build a roof because light is their enemy. Earthworms need moisture to live, and light destroys a layer of slime on their bodies that keeps them wet.
To protect themselves in really dry weather, earthworms dig deeper into a wetter layer of soil. Or they curl up in a ball in their tunnels and go to sleep. In winter, they sleep for months until springtime, the way bears and other animals do.
Earthworms may come out of their holes during a bad rainstorm, especially if it's at night, because their holes get flooded. (In Russia, earthworms are called "rain worms.")
Delicious, too, for some
Worms are an important source of food for many animals. Birds, moles, toads, hedgehogs, and many others find worms delicious. And, yes, in parts of India, Australia, and South America, people cook and eat worms.
Worms help humans, but humans don't always return the favor. Until the mid-1800s, people thought that worms were plant-eating pests. And today, many of the fertilizers used by farmers are bad for worms.
Yulia Sayapina wishes people would follow an old Russian tradition. It might help worms. "In the villages of old Russia," she says, "there were fall days when you couldn't go into the forest, because you'd disturb the animals getting ready to go to sleep in winter." That included frogs, snakes, insects - and worms.
LUNCHING AND BEING LUNCH:
A robin tries to pull a worm from its hole. The earthworm expands to grip the sides of its burrow with tiny bristles. Another worm is starting to drag a meal of leaves down its hole. Common night crawlers can grow to be a foot long, burrow up to six feet deep, and live for five to 10 years. They were brought from Europe. Pioneers who settled north of Long Island, N.Y., found a land that had been scraped clean of worms by glaciers.
A worm deposits its eggs in a ringlike cuff that forms near its head. The worm wriggles through the cocoon, which closes around the eggs afterward. Weeks later, tiny worms emerge.
SUMMER BREAK: Worms are most active in the spring and fall. When it's too hot or too cold, they take long sleeps in mucus sacks. The sacks keep them from drying out.