The earthworm is an invertebrate animal. Its ancestors lived in the sea, but the earthworm is usually found in the ground. Sometimes he comes up too, for example when he mates.
It is unknown where the name “earthworm” comes from. Maybe it is an “active worm”, i.e. a worm that moves. Or it got its name from the fact that it comes to the surface when it rains. It is also not known exactly why he does this – he could actually survive two days on the wet ground. There are even species that live in lakes or rivers.
Earthworms eat their way through the earth. They feed on decayed plants and humus soil. This will loosen up the soil. Plants also feed on earthworm droppings. It must not be too warm and not too cold for earthworms. In the winter they hibernate.
200 years ago it was still believed that earthworms were harmful. We now know that they are very good for the soil. There are even worm farms: earthworms are bred there and then sold.
Not only gardeners buy worms, but also anglers for the fishing hook. Fish like to eat earthworms, as well as many other animals such as moles. Earthworms are also part of the diet of birds such as starlings, blackbirds, and thrushes. Larger animals like foxes like earthworms, as well as small ones like beetles and frogs.
What is the body of an earthworm made of?
An earthworm has many small grooves. It consists of links, the segments. An earthworm has around 150 of these. The earthworm has individual visual cells distributed over these segments, which can distinguish between light and dark. These cells are a simple type of eyes. Because they are distributed all over the body, the earthworm recognizes where it is lighter or darker.
A thicker part is called the clitellum. There are many glands there from which mucus comes out. The mucus is important in mating because it gets the sperm cells into the right openings in the body.
The earthworm has a mouth at the front and an anus at the end where the droppings come out. From the outside, both ends look very similar. However, the front is closer to the clitellum, so you can see it well.
Many people believe that you can cut an earthworm in two and the two halves live on. That’s not quite true. It depends on what is cut off. If only the last 40 segments are cut off from the rump, it often grows back. Otherwise, the earthworm will die. A maximum of four segments may be missing at the front.
Just when an animal bites off a piece of the worm, it injures itself so much that it cannot survive. Sometimes, however, the earthworm intentionally separates a part of itself. If the rump is grabbed, the earthworm tries to lose it and escape.
How do earthworms reproduce?
Every earthworm is simultaneously a female and a male. This is called a “hermaphrodite”. When an earthworm is one to two years old, it becomes sexually mature. When mating, two earthworms nestle against each other. One is different than the other. So the head of one is at the end of the body of the other.
Both earthworms then expel their seminal fluid. This then goes straight to the egg cells of the other earthworm. A sperm cell and an egg cell unite. A tiny egg grows out of it. On the outside, it has different layers for protection.
The worm then expels the eggs and leaves them in the ground. A little worm develops in each one. It is transparent at the beginning and then slips out of its shell. How many eggs there are and how long it takes to develop depends heavily on what type of earthworm it is.