Cave divers were exploring the depths of a subterranean lake in southeastern Europe when they made a discovery that will surely delight fans of Game of Thrones. Casting their flash beams through the murk and gloom, they spotted a number of strange, slow-moving animals that looked suspiciously like dragons.
Dragons are typically associated with the elements of fire and air, but various ancient myths do recount water-dwelling dragons. In 1689 natural historian Johann Weikhard von Valvasor observed that certain Balkans people had developed a rich folklore. It concerned watery dragons that lived beneath the surface of the Earth. And, incredibly, many people claimed to have seen them.
In far more recent times, thanks to technological advances in cave diving, scientists have been able to explore the harsh underwater area where the “dragons” were thought to live. The depth was extreme, and light was almost non-existent. But if a dragon was going to live anywhere, wouldn’t it be in a place that is inhospitable to humans?
The “dragons” are in fact endemic to a vast network of aquatic caves in southeastern Europe. Encompassing the karst of the Dinaric Alps, a rugged mountain range that skirts the Adriatic Sea, their habitat includes parts of southern Slovenia, Italy, Bosnia and Herzegovina and Croatia.
In 2017, then, the Croatian group Association Hyla organized a team of “dragon hunters.” Made up of international cave divers and biologists, the team had chosen as their site of study a Croatian lake called Zagorska pec. In fact, it’s one of several such habitats identified by the organization in recent years.
The “dragons” in question are actually a rare species of salamander known as olms (Proteus anguinus). And the fact that they sometimes wash up after heavy rain means that people in the past incorrectly identified them as baby dragons. Still, looking at the animals, it’s easy to see why.
Sometimes known as “human fish” owing to their pinkish skin color, olms are small, eel-like creatures with narrow, cylindrical bodies. They reach up to 16 inches from head to tip and resemble tiny dragons. Moreover, they live and breed entirely under the water, with external gills enabling them to breathe.
The first official record of the species was made by Valvasor in the 17th century, and he described them in rather unflattering terms. “Barely a span long, akin to a lizard,” he wrote in The Glory of the Duchy of Carniola, a 15-volume encyclopedia. “In short, a worm and vermin of which there are many hereabouts.”
But, in fact, olms are neither “worms” nor “vermin.” Indeed, on closer examination, they’re rather special creatures. For one, their sensory organs have adapted to an entirely dark habitat. Virtually blind, they have eyes that are actually buried behind a layer of skin and are useless for orientation.
To compensate for their poor vision, olms have a range of other receptors, though. Using their noses and mouths, they’re able to sense organic compounds within the water. Their acute hearing, meanwhile, enables the detection of distant sounds and vibrations. Finally, olms possess a unique organ that allows them to sense electromagnetic fields, possibly for navigation.
As if all that weren’t enough, the creatures are able to live for over a century. For sustenance, they prey on tiny snails, insects and crabs. And, incredibly, they can each survive a decade without food by lowering their metabolic rate and drawing on stores of glycogen and lipids. Added to which, the latest research indicates that they thrive at astounding depths and pressures.
“Study of the olms in greater depths is extremely important, especially when done by divers focused on conservation,” biologist Gregor Aljančič, head of the Tular cave laboratory, told New Scientist in June 2017. “Our previous findings indicate that Proteus can withstand significant pressure.”
Indeed, the olms located in Zagorska pec were found at an astonishing depth of 370 feet – more than three times the depth of a so-called “recreational” dive. At those depths, divers require hypoxic air tanks to counter the risk of oxygen toxicity. And, as always, there is a life-threatening risk of nitrogen narcosis.
“This was the deepest finding of the olm ever recorded,” Petra Kovač-Konrad, the leader of the expedition, told New Scientist. “We [also] spotted specimens at many different depths in the lake, which confirms the assumption that depth of the water isn’t the stress factor for the olms.”
The distribution of the olms in fact appeared to be determined not by depth or pressure, but by certain other environmental factors. “Olms prefer specific parts of the cave system with less stressful conditions, such as slower water flow or [a] bigger amount of sediment,” said Kovač-Konrad.
Worryingly, meanwhile, efforts to study the olms are being driven by urgent conservation concerns. Pollution in the form of fertilizers and leeched pesticides, as well as lead and mercury, is increasingly contaminating the olms’ sensitive underwater habitat.
In fact, due to the olms’ decreasing numbers, the International Union for Conservation of Nature has placed them on its list of threatened species. Now, scientists are racing against the clock to learn as much as possible, but their efforts are inevitably limited by their technical skills in cave diving.
Fortunately, 21st-century technology offers the possibility of creative new research strategies. For example, thanks to DNA analyses of cave water, scientists have recently located five new olm habitats. And Gergely Balázs, from the international Proteus Project, intends to use infrared cameras to study olm behavior.
To date, however, most scientific data concerning olm behavior has been acquired using captive specimens. In 2016 the creatures were successfully bred in captivity – a remarkable feat given that they lay eggs just once or twice every ten years. And the behaviors observed in the now adolescent olms have included hunting, territorial defense and “brotherly quarrels” over food.
Meanwhile, the olm continues to be a proud symbol of Slovenian heritage. Indeed, few countries can boast “dragons” among their natural assets – Indonesia with its Komodo dragons being one exception. Moreover, even if they are somewhat small – and, sadly, incapable of flying or breathing fire – olms are enchanting animals that deserve to be studied and protected. With any luck, they’ll survive long into the future, too.