Earthworms are hermaphrodites. Each has both male and female sex organs, but they cannot fertilize themselves. Earthworms spend most of their lives underground, creating complex burrow networks. They make an essential contribution to soil fertility and are therefore very important in gardens and of farm land.
Amazing Facts About the Earthworms
- There are thought to be 4,400 species of earthworm!
- As the earthworm spends most of its life underground, ploughing through the soil and creating complex burrow networks (that may extend 2m or more beneath the surface), their bodies are basically like a tube of muscle arranged in two layers. One set of fibres run lengthways and another run widthways like a corset around its body. Tightening the ‘corset’ forces the worm’s head forward. A wave of contractions then passes back down the body, squeezing more of the worm forward until the long muscles take over to pull up the tail.
- Earthworms have tiny retractile bristles along the body which help give it grip and a slippery mucus covering, allowing the worm to move through even the hardest earth.
- The thin-skinned earthworm has no resistance to the sun’s ultra-violet radiation, so daylight can be fatal and they will usually only be found on the surface in dull, wet weather.
- Earthworms will anchor their tail in its burrow and at any sudden noise it will slither back into the earth.
- Earthworms are hermaphrodites. Each has both male and female sex organs. However, they cannot fertilize themselves. They need to mate with another worm in order to exchange genetic material.
- Earthworms are attracted to one another by scent. Their mating ritual involves the two worms lying head-to-tail on the surface of the soil and exchange sperm while bound together in a mucus covering.
- Earthworms can contain up to 20 eggs which are sealed up to form a cocoon and which can survive extreme weathers, but usually only one worm emerges from it.
- If an earthworm loses one end of its body it may grow a replacement, however, if it is cut in half, it dies. Contrary to common belief, they do not become two new worms.
- Some gardeners poison earthworms to eliminate worm-casts (droppings). This damages the lawn and animals and birds preying on the worm more than it damages the earthworm population.
- Fossilized worms, similar to earthworms, have been found in rocks laid down 600 million years ago.
Are earthworms important?
- Yes! The earthworm is such a familiar creature that it is rarely given a second thought, yet its contribution to soil fertility is enormous. They tunnel through the ground, eating their way through the soil. They also drag leaves and other plant debris down into the soil, which allows air to enter it and water to drain through. Their activities over millions of years have been vital in creating rich, fertile soils from dense, infertile clays.
- Many animals get their food from the soil, but the earthworm eats the soil itself. It crunches it up in its muscular stomach, digests what it can (the organic material that is mixed with the mineral fragments) and ejects the rest.
- Earthworms cast from one square metre of meadow were weighed over the course of one year. It emerged that the worms brought about 8kg of soil to the surface annually.
- Unfortunately for the earthworm, it falls prey to just about most animals and birds, but the mole is its greatest threat as one mole can eat up to 50 earthworms in one day and they consume more in the winter.
- Type: Invertebrate
- Diet: Herbivore
- Lifespan: Up to 6 years
- Size: Up to 35 cm, although typically around 8 cm
- Weight: Up to 11g
- Habitat: Soil
- Range: Europe, Asia and North America
- Scientific name: Lumbricus terrestris