A tenth already gone

Around seven percent of the animals that do not live in the sea are probably already extinct. Conservative prognoses assumed that around 100 species disappear from the earth every day due to human activities. This biological catastrophe leads to the sixth mass extinction on this planet. It is believed to be the largest after the extinction of the dinosaurs.

Concrete references to the species that are becoming extinct have been few and far between. Only around 800 species of the around 1.9 million named have so far been confirmed to be extinct. Claire Regnier's team assumes that this fact is due to the fact that only a few scientists are studying the extinction of invertebrate species. However, they account for around 99 percent of biodiversity.

The researchers examined databases and museum collections and sought expert opinions in order to arrive at an estimate of the losses in land snails. There are comparatively good records for these species. According to the results published in the scientific magazine «PNAS», around a tenth of the 200 known species have probably already died out.

Extinct before discovery

The question remains how many still unknown invertebrate species live on earth – species that could become extinct before their existence is even known. Estimates in recent years have assumed that it could be 100 million.