Wundersame Weichtiere

Which animal has thousands of teeth, no skeleton and only one foot? Which animal can carry both male and female sexual organs and manages to move unharmed over sharp knife edges? That's right, a snail! Snails are often labelled as slimy, boring or even annoying. However, these wondrous molluscs are fascinating survival artists.

Survival artists

Snails (lat. Gastropoda) belong to the molluscs (lat. Mollusca). Due to their high adaptability, they colonise the most diverse habitats. They are the only molluscs to have evolved to live on land. Even in urban areas, snails are not uncommon. Often different species are especially adapted to their habitat. This specialised adaptation is important because snails, as is generally known, are not among the fastest animals and are thus bound to a comparatively small habitat.

Protected by mucus…

Like all molluscs, snails do not have a skeleton. They consist of a soft body that cannot be clearly divided into different body parts. There is a head, but where it ends and where the "rest" of the snail, the so-called foot, begins cannot be clearly determined. For this reason, the entire soft body is called the "head-foot". It is surrounded by a layer of mucus to protect it from drying out. This layer has a water-attracting effect because it contains so-called mycoproteins, which swell up when exposed to water and bind the water. Anyone who would try to wash off the mucus of a snail with water would fail.

Snail mucus also fulfils other important tasks: When threatened, it can be lathered with air bubbles, which causes smaller enemies, such as ants, to stick to it. The slime is also of fundamental importance for locomotion. It reduces friction and protects against injuries from sharp surfaces. It also helps the snail to stick to the ground so that it can crawl vertically and upside down.

...and shell

Snails not only feel at home in many different habitats. Most of them even carry their own "house" around with them permanently and are therefore called shell snails. Their "house" is called a gastropod shell and is usually asymmetrically curled to one side. This feature makes it easy to distinguish between different species.

Hidden in their shells under foliage or even in the upper layers of the soil, snails with shells can survive long dry periods and winter. They are able to repair their shells, as these consist mainly of lime minerals, which are dissolved out of the substrate via the soft body and absorbed. Some snails even gnaw on their conspecifics to get their lime!

Nützlich für die Forschung und wichtig für das Ökosystem

Als sogenannte Bioindikatoren liefern Schnecken der Forschung Einblicke in die ökologischen Belastungen ihrer unmittelbaren Umgebung. Schnecken verfügen über die Fähigkeit, über ihre Nahrung und den Kontakt mit dem Untergrund Schwermetalle wie z.B. Kupfer, Eisen oder Calcium aufzunehmen und in ihrem Körper zu binden. Schwermetallbelastungen entstehen oft durch den Menschen und können verheerende Auswirkungen auf Ökosysteme haben, da sie auf viele Organismen toxisch wirken. Durch die Beprobung von Schnecken in einem Lebensraum kann ermittelt werden, ob und welche Schwermetalle vorhanden sind.

Schnecken sind also durchaus nützliche Forschungsassistentinnen. Das ist allerdings nur ihr "Nebenjob". Hauptsächlich spielen sie als Zersetzer (Destruenten) eine wichtige Rolle im Ökosystem. Mit ihrer Raspelzunge, der sogenannten Radula, die mit tausenden kleinen Zähnchen besetzt ist zersetzen sie z.B. tote Pflanzenteile. Sie ernähren sich aber auch von lebenden Pflanzenteilen, Flechten und Pilzen. Gleichzeitig dienen sie selbst vielen anderen Organismen wie Vögeln und Säugetieren als Nahrungsquelle. Diese oft unscheinbaren und unterschätzten Funktionen machen die wundersamen Weichtiere zu einem unverzichtbaren Bestandteil ihrer Ökosysteme.

Discovering snails in the city

If you are now curious and would like to observe snails in their natural environment, you could do so in the city! There are a variety of habitats, from city parks and allotments to wastelands, cellars and walls, where snails can be discovered. As snails need constant protection from drying out, they can often be seen at night, in the early morning or late evening and especially after rainfall. Many species reproduce during the warm months, which is why there are particularly many individuals in autumn. On hot days in summer as well as during the winter months, most species retreat into their shells and spend longer resting periods hidden under stones, leaves or even buried in the upper layers of the soil.

Once you have discovered a snail, you can identify it using the Naturblick-App by selecting specific characteristics of the snail you found. Have fun discovering and identifying snails in urban spaces in Germany!