New Snail Species with Transparent Shell Discovered in Croatia

translucent-snail

By Samba Lampich

A tiny and fragile snail with a dome-like translucent shell has been discovered in the Lukina Jama– Trojama cave system in Croatia.

A Rare Find Deep Underground

The cave-dwelling snail species was discovered in 2010 by a team of cavers and biologists with the Croatian Biospeceological Society who were on an expedition to determine the caves’ depths. The team collected all animal specimens found along the way, since deep cave crevices are often promising places to find new species, and came across one living specimen of the new snail and eight empty shells at a depth of 980m. They gave the live snail and shells to taxonomist Dr Alexander Weigand of the Goethe University Frankfurt in Germany for identification and classification. Weigand determined that the living specimen was a new species, Zospeum, tholussum and that was related to other known species. “The single living specimen was found in an unnamed large chamber with lots of stones, rocks and sand. A temporal small stream of running water was present close to the collecting site. Air temperature was between 3.3° to 3.5°C, water temperature 5.1°C and air humidity 100%. Shells were observed beginning from 800m depth till the bottom of the cave. Shells were generally found on layers of mud,” Dr Weigand wrote in a paper published in the open-access journal.

Living with no Rush

The Zospeum tholussum shell has no pigmentation and has a height of less than 2mm (0.08 inches) and a width of about 1mm (0.04 inches). The species belongs to a genus of minute air-breathing land snails that cannot see to find their way around and are considered to be true eutroglobionts that only live in dark, underground caves. The tiny species moves very slowly, even for a snail. “They only creep a few millimeters or centimeters a week, and mainly in circles, grazing at one point where they live,” Weigand said. Because the species was found so close to water and in a muddy environment, Weigand suspect that the snail is dispersed passively, either by running water or by animals such as bats and crickets.

Classroom Discussion

  • How and why do some snails hibernate?
  • What are some permanent cave dwellers and how have they adapted to living in their environment?