“Plants, animals, fungi and microorganisms purify water and air and ensure fertile soil. Intact self-cleaning powers of the soil and water bodies are important for the production of drinking water. The natural fertility of the soil ensures healthy food. All this does not work mechanically, but takes place in a complex system of interactions. Ecosystems have a high absorption capacity and regenerative capacity – but they are not resilient at will” (National Strategy on Biological Diversity 2007).

The unexpected diversity under our feet

A single gram of soil contains billions of microorganisms, such as bacteria, fungi, algae and protozoa. One square meter of healthy soil is home to hundreds of thousands to millions of soil animals, such as threadworms, earthworms, mites, millipedes, centipedes, woodlice, springtails, insects and their larvae. If you extrapolate this to one hectare (= approx. 1.5 soccer fields), you get approx. 15 tons live weight (!), which corresponds to the weight of about 20 cows. So there are much more organisms living in the soil than on the ground and the variety of species is also higher. It is estimated that up to 50,000 species of ground animals live under our feet in Germany alone!

All a question of size

The ground animals are divided into different sizes or classes of smallness.

Microfauna (< 0.2 mm): e.g. threadworms, water bears, rotifers

Mesofauna (< 2 mm): e.g. springtails, mites

Macrofauna (< 20 mm): e.g. earthworms, millipedes, centipedes, woodlice, insects, spiders

Megafauna (> 20 mm): e.g. moles, mice

The small service providers

The soil animals or soil fauna (named after the Roman goddess “Fauna”, goddess of the forest and animal species) play a key role in the natural soil functions. Through the decomposition and conversion activity, for example, dead plant waste is worked into the soil, crushed and thereby better decomposed by bacteria and fungi. In this way the nutrients are released again in a form available to the plants (mineralization). In addition, soil crawling and digging animals provide for the mixing, aeration and loosening of the soil (bioturbation). They contribute significantly to the formation of stable clay-humus complexes with a high storage capacity for water and nutrients and ensure fine-crumbly soils that can be removed less quickly by erosion. In addition, they are to a certain extent able to break down harmful substances.

Soil is a habitat with complex communities and is of enormous importance for biodiversity. Although it lies directly under our feet, we do not yet know very much about the biology of soil, despite decades of soil biological research. The small size of the soil fauna and the diversity of species also play a role here.

EXPERIENCE yourself

Experience the big world of small ground animals and turn over stones, look in the compost heap and find out what lives in your city! Go to the compost heap and find out what lives there! Burrow them in the litter in your favorite forest, look under rotten wood!

Use our interactive identification keys to find out which ground animals you have found. Report your finds and contribute to the knowledge of these animals.