The lowly earthworm is a jack of all trades. It fertilizes, stabilizes and aerates soil - out of sight and out of mind. Some may find them icky, but they're a vital part of our ecosystem.
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Slimy and squirmy are just two of the choice words some would use to describe earthworms. But far from being disgusting creatures at home in the dirt, these wriggling invertebrates play a vital role in nature.
Even Charles Darwin, famed author of the theory of evolution, devoted a lot of time to considering the humble earthworm and believed it is one of the most important species to grace the planet.
"According to Charles Darwin, no living thing has had such a profound impact on history as has the earthworm," writes Christopher Lloyd, who authored "What on Earth Evolved?: 100 Species that Changed the World."
Check out our picture gallery to find out why!
Silent underground helpers
The lowly earthworm is a jack of all trades. It fertilizes, stabilizes and aerates soil - out of sight and out of mind. Some may find them icky, but they're a vital part of our ecosystem.
Image: picture alliance/dpa/M. Schutt
Half truths
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.
Image: Colourbox
Conscientious composter
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.
Image: Colourbox
Soil stabilizers
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.
Image: picture-alliance/dpa/S. Sauer
Has an earthworm got a head?
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.
Image: picture alliance/blickwinkel/J. Fieber
Tiny tunnellers
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.
Image: Colourbox
Prime plumbers
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.
Image: picture-alliance/blickwinkel/F. Hecker
Close quarters
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.