A holotype of a Zospeum tholussum (Wiki Commons).

A new snail species, Zospeum tholussum, was recently discovered after a team of cavers and biologists went on an journey to determine the depth of Lukina Jama-Trojama cave in Croatia, one of the 20 deepest cave systems in the world. 

While traveling through the cave, the team came upon one living sample of this new species more than 3,000 feet underground. They also found eight empty shells, ranging from an average of 1.4 to 1.8 millimeters tall.

Though this animal has been classified as a new species of snail, scientists have categorized Zospeum tholussum within the Zospeum genus. 

Zospeum tholussum lacks eyes and has no pigmentation on its shell, but neither of these traits would serve a purpose, since this animal lives in complete darkness.

The Zospeum tholussum crawls only a few millimeters or centimeters a week, but has managed to find alternative ways to travel. Due to their limited mobility, scientists believe that these snails often attach themselves to other animals or travel by water current to cover more ground. The discovered empty shells were found beginning at a little over 2,500 feet into the cave all the way to the bottom of the cave. In addition, these shells were generally found on layers of mud close to a stream of running water. 

The discovery of other differently shaped shells suggest that there are other snail species living within Lukina Jama-Trojama, but a live capture is required to confirm these snails’ existence. 

Reach Staff Reporter Janelle Cabuco here.