Gregor Aljančič enters a concrete tunnel and descends into a subterranean world below the city of Kranj, in northern Slovenia. Lamps illuminate his one-minute walk down the claustrophobic passageway, which fades to pitch black as he reaches the main chamber of Tular Cave Laboratory. The 50-year-old has visited the laboratory since boyhood, when he came with his father, the lab’s founder, and he knows its occupants well. The reinforced natural cave, once a World War II air raid shelter for a factory, now serves as a safe haven for blind salamanders known as olms (Proteus anguinus). Aljančič, a cave biologist, visits every other day to ensure conditions remain comfortably dark and damp for his study subjects.
“Continuing father’s work was at first an obligation, but then it became my passion too,” he says. “Many of these animals I’ve known since before I can remember. They’re all still alive.”
Aljančič uses night-vision goggles and the dim beam of a headlamp to search pools of water for olms slung over rocks or wedged into crevices. Direct illumination disturbs the salamanders. When light strikes, their translucent skin flashes like crescent moons and they dash for darkness, swimming in exuberant wriggles beneath the limestone ledges.
Aljančič’s father, prominent cave biologist Marko Aljančič, established the lab in 1960. He built an assemblage of concrete pools, and over time filled them with olms from cave systems in southwestern Slovenia, dedicating his life to studying their cryptic behaviour. But his amphibian charges outlived him, as he came to suspect they might. Gregor Aljančič estimates that individuals could survive to be a century old, but like many other aspects of olm biology, no one knows for sure.
While Tular Cave Laboratory mainly serves researchers, everyday Slovenians are well aware of the olm’s existence. Slovenia is the birthplace of cave biology as a formal discipline, and it was here that olms were first encountered. Today, they are an attraction at Postojna Cave Park, one of the country’s most popular tourist destinations. Visitors can ride a train through the cave, which showcases the dramatic pillars (tchlo-VESH’-khah REE’-bee-tsah). The Slovenian name translates to “human fish,” but most observers don’t fully appreciate how much they share with an animal that lives its whole life in darkness.
