A German man whose hobby is diving underground has discovered what scientists claim to be the first cave fish discovered in Europe.
First Cave Fish Discovered In Europe
Spelunker Joachim Kreiselmaier accidentally found the fish in August 2015 while he was exploring South Germany's Danube-Aach cave system. Species of cave fish have been found in every continent except Antarctica and Europe and the discovery marks the first time a cave fish was found in Europe.
The cave fish is also the first to have been found so far north. The loach in the genus Barbatula was found thriving 760 kilometers (472 miles) further North than the the Pennsylvanian cave sculpins, which hold the previous record.
The isolated species likely entered the cave system after the last Ice Age as the melting of the alpine glaciers allowed them to colonize the new area. Prior to the discovery, it was believed that glaciations during the Pleistocene prevented fishes from colonizing subterranean habitats north of 41° latitude.
Characteristics Of The Cave Fish
The newly discovered fish looked like the stone loaches but it has smaller eyes, large nostrils, longer whisker-like barbels, and nearly no color on its body, characteristics that may have helped the creature thrive in its habitat.
Kreiselmaier was exploring the the deepest parts of the Danube-Aach, which can only be reached in the summer and fall when conditions are dry, when he noticed the strange-looking fish. He decided to take some photos of the creature and showed them to hobby geologist Roland Berka.
Jörg Freyhof, from the Leibniz Institute for Freshwater Ecology and Inland Fisheries (IGB) in Berlin, later confirmed that the characteristics of the fish show cave adaptations.
"It took someone with the 'right eye' to realize that this might be something special and I believe that, on top of the right conditions and the difficult trip," said Jasminca Behrmann-Godel, from Germany's University of Konstanz, who, along with Freyhof, Berka, and Kreiselmaier, described the cave fish in a study published in the journal Current Biology on Monday.
Researchers were able to study the features of the fish in better detail after Kreiselmaier caught a live specimen in November 2015, which was followed by a catch of four more fishes.
Genetically Distinct Species
Researchers said that the cave loaches are a genetically distinct species and that it likely arose within the last 20,000 years and has adapted to life underground. The researchers likewise said that the findings suggest that adaptation to subterranean habitats can be fast and requires only a few thousand years.
"Population genetic analyses based on microsatellites indicated that cave fish are genetically isolated from populations in surface habitats and exhibit reduced genetic variability," the researchers wrote in their study. "The newly discovered European cave loaches do not represent individuals displaced from surface populations, but they follow a unique evolutionary trajectory towards cave life."