life cycle

Earthworms
Earthworms live everywhere in the world where there is soil.
Earthworms eat as they burrow through the soil
Earthworms do not have teeth
Earthworms help make the soil healthy
Earthworms lay eggs

Species
There are about 2 700 species (different kinds) of earthworms around the world.

Earthworm bodies
Earthworms are invertebrates, which means they don't have backbones.
Their soft bodies can be brown, pink or even red.

Did you know? In the Philippines there are blue earthworms and one kind in the United Kingdom is green!



Earthworms have a brain, 5 hearts and parts inside their bodies which help them to breathe. The earthworm's body is covered with chemoreceptors (say kee-mow-ree-sep-tuz) which is how the worm tastes things. Chemoreceptors are tiny sense organs which detect chemicals in the soil.

Earthworm sizes
The smallest earthworms are about 1 centimetre long and the largest can be 4 metres long. One of the largest earthworms is the Giant Gippsland Earthworm, found in one part of Australia. There are large earthworms in South Africa too.


Earthworm Life Cycle
Earthworms are hermaphrodites (say her-maff-row-die-ts). This means that each earthworm has male parts that produce sperm and female parts that produce eggs. All earthworms lay eggs.

When two earthworms mate, they lie together, and cover themselves in sticky mucus, and pass sperm into each other's body. The sperm makes the eggs inside each earthworm's body grow.

A thick ring of slime forms around each worm's body and as the earthworm wriggles forward, the ring with eggs inside it slips off and is left on the ground. The ring closes at both ends and becomes a hard cocoon that protects the eggs.

The eggs hatch after two weeks if the weather is warm, but they can take up to three months to hatch when it is cold. Usually one or two earthworms hatch out of each egg. The young worms are about 12 millimetres long and light pink in colour. Earthworms are able to mate when they are twelve months old.


How earthworms help soil and plants
Earthworms dig large burrows which let water and air into the soil. This helps stop erosion and lets the water and air get down to the roots of plants. The burrows also helps plant roots to move more easily through the soil and into new spaces. Worms drag leaves and plant bits down into the earth. As they burrow, the worms swallow soil and eat the plant matter that is in it. The soil they swallow passes though the worm's body and is left in little piles on top of the ground. This is called castings and is excellent fertiliser (food for plants). People who farm worms do it to collect the castings to sell to gardeners.