A scurrying census: 99 species of tardigrade live in Germany

Whether bird, hare, or wild cat, the exact number of species in Germany is well-documented for these and most other animal groups. But for some groups, knowledge about their biodiversity is almost forgotten or is based on data that is decades or even centuries old.

One such group is the tardigrades. A fascinating and remarkably resilient species, they were discovered in Germany over 250 years ago. The only scientific documentation of their diversity dates back to 1936. However, since then, many more tardigrade species have been discovered, including by Stuttgart zoologist Ralph Schill. “I've been working with tardigrades for over 20 years,” says Schill, who conducts research at the Institute of Biomaterials and Biomolecular Systems. "We have identified 1,488 tardigrade species worldwide, but until now, the number native to Germany remained uncertain."

The first zoological record of the tardigrade dates back to 1773, when Quedlinburg pastor Johann August Ephraim Goeze discovered these tiny creatures in a pond behind his church. Describing them, he wrote: "This little animal is remarkable, not only because its entire body structure is extraordinary and unique, but also because, at first glance, its appearance most closely resembles that of a miniature bear. This is what inspired me to name it the 'little water bear.'"

Bärtierchen können sich hervorragend an eisige Kälte und trockene Dürren anpassen. Sie halten ihre innere Uhr an und fallen in eine Art Dornröschenschlaf. In diesem Zustand altern sie nicht. „Diese Eigenschaft fasziniert mich besonders“, so Schill.

Tardigrades are excellent at adapting to icy cold and dry droughts. They stop their internal clock and fall into a kind of slumber - like Sleeping Beauty. They do not age in this state. “This characteristic particularly fascinates me,” says Schill.

These smart skills were already known to zoologists in the 1930s. In 1936, Ernst Marcus published an overview of all known tardigrade species in Germany in the series “Die Tierwelt Deutschlands”. The first and only tardigrade checklist to date comprises 44 species.

The Stuttgart zoologist Schill has since discovered several new species of tardigrade. Together with his research colleague Dr. Rolf Schuster, he meticulously reviewed all scientific works published since 1834 and compiled an updated checklist of all tardigrade species recorded in Germany to date.

The two researchers have counted 99 species in total. This includes 91 species that primarily inhabit mosses and lichens, along with eight species that thrive in brackish and saltwater along Germany's coast. Of the 1,488 known tardigrade species worldwide, 24 were discovered and described for the first time in Germany.

“The species found here make up around seven percent of the world's known species,” explains Schill. “And now, for the first time in almost 100 years, we have an up-to-date overview of all tardigrades in Germany. This is particularly important as the decline in biodiversity has accelerated dramatically in recent decades and is the only way we can understand how this affects the individual animal groups.”

Publication
Schuster, R., Schill, R.O. Checklist of tardigrades in Germany as a contribution to biodiversity research. Org Divers Evol (2025). DOI:10.1007/s13127-024-00668-5.