The story goes that when an earthworm is split in two, both parts will live on. That's not exactly right. Only the front of the worm can survive such a trauma. Even then, it doesn't always make it. All of the worm's vital organs are here but if too much of the gut is missing or the wound becomes infected, the half worm won't recover.

Worms satisfy their hunger with the remnants of dead plants. They also graze on bacteria, algae, single-cell organisms and fungal threads located in their tunnels. Because earthworms have no teeth, they compost organic material by sticking food to the walls of underground burrows and layering excrement over it. This creates a perfect environment for pre-digesting microorganisms.

The earthworm's cast material – also known as worm poop – helps create good soil's fine crumb structure. Each year, the animals will lay a 0.5 centimeter crumb layer on the soil surface. But if they are really industrious and conditions are right, it can be up to five centimeters. These casts are packed full of nutrients that provide food for fungi and help prevent soil erosion.

Earthworms have a head and tail, although that may be hard to tell at first glance. If the animal is at reproductive age, a thick band, called a clitellum, is visible. The head is located closest to this band.

An earthworm's tunnel system is a big boon to the soil. It allows water to flow more quickly through the ground and provides ventilation. Plants also push their roots through the many, many tunnels created by earthworms. A 50-hectare farm can house up to 400,000 kilometers of underground passages.

An earthworm's true domain, as its name betrays, is underground. But at times, the animal is lured above ground by the vibration of raindrops hitting the earth's surface. There, dangerous UV-light and hungry birds await.

A ground without earthworms behaves like a blocked drain when it rains. Water can no longer flow down through the soil. Even the smallest amounts of water can cause flooding over time. However, when worms are present and working diligently, soil can deal with the intake of water and surplus liquid ends up in springs and wells.

The number of earthworms living in the soil depends on how the land is cultivated. In monocultures, where many machines and pesticides are used, you'll find around 30 animals per square meter. But the same amount of soil on a farm that practices multi-cropping can contain up to 120 animals. In optimum conditions, up to several hundred of the invertebrates may be working silently underground.