(CNN) – The Postojna Caves, located an hour’s drive southwest of Ljubljana, the capital of Slovenia, are so vast, it has its own railway.
And yet, one of the cave’s main attractions is something at the other end of the size spectrum – and completely unique to Postojna.
Little dragon!
It has been known to locals for centuries and has graffiti, dated 1213 to prove it. Tourists began to arrive in large numbers after the first visit in 1818 by the Austrian Franz I, the last Holy Roman Emperor of Europe. About 35 million people followed him.
It’s easy to see why. The cave is so large that a small train runs at either end of its 24 km network of underground chambers and tunnels.
The train line ends at the massive Parliament Hall, where the Milan Symphony Orchestra performed in 1930. From there, a walking path traverses six geological formations, crossing a bridge over a chasm by the rocks. Russian prisoners of war built during World War I and continue to pass through the reef peaks and gorges, noodle-thin stalactites and marble curtains.
Journeying down to a depth of 115 meters (377 feet), it sometimes takes visitors through slits just one meter wide.
However, the adrenaline rush is really saved to face the strange creatures found in the Postojna cave system and nowhere else on Earth.
Blind iguana
Olms grow up to 25 cm in length.
Postojna cave courtesy D. D
Olms, or proteus anguinus in Latin, are blind salamanders, about 25 cm long, that never outgrow their immature, water-deprived stage.
The locals call them baby dragons because they were washed away from Postojna in the flood and, since the caves are home to dragons, this must be their baby, right?
Today, visitors can catch them swimming among the rocks in a purpose-built aquarium deep in the cave.
“Cute, isn’t it?” asked Mateja Rosa, a big olm fan who works as Postojna’s PR and marketing manager.
They really are. Similar in appearance to toys, they are sometimes called human fish because – despite living in the water – they have smooth, pinkish-white skin instead of scales and limbs with cartoon-like fingers underneath. their busy red.
They may be blind, but the olms seem to hear the visitor’s approach, seeming to be sensitive to vibrations. One even attached itself to the glass tank near where my face was looking.
Curious? Is it friendly?
Not so, according to Primož Gnezda, a young, enthusiastic biologist who has been studying these creatures for many years.
Gnezda said during a tour of the Vivarium, an exhibition space next to the cave that displays more olms and a host of other Postojna creatures.
The seemingly friendly olm is known for its unusual, but not sociable, behaviors.
“It’s always spread over the glass for safety,” says Gnezda. “That it appears next to your face is just a coincidence.”
Table manners
Visitors to Postojna can see olms in an aquarium.
Image Jure Makovec / AFP / Getty
According to Rosa, olms can live up to 100 years and can survive for long periods of time without eating.
“Definitely seven years,” she said. “For the first two – three years, there is no problem. Then they start to lose weight, stop moving and simply wait for the prey to pass. Longer than seven years and some may die, some may die. can survive, depending on the individual’s metabolism.”
When they find food, we can forgive their behavior.
“We feed them worms,” says Gnezda. “The worms form a little ball together in the water and the olms come and grab it like a vacuum cleaner. Sometimes they eat so violently that you can see the worms come out of the gills with the water.”
Vivarium leads to the laboratory, where scientists have a permit to store 10 olms for research. A lot of money is spent on these creatures.
“Biologists are studying their DNA,” says Gnezda. “Their genome is like a novel. It’s 16 times longer than the human genome and more complex.”
“You also have a lot of blanks. We don’t know why they exist. Imagine a 600-page book where all the words are jumbled up and we have to reconstruct the story.”
Is there any reason why we care so much?
“Their ability to regenerate is amazing. If they lose a limb, they grow back. The idea of the study was to find out the mechanism behind it.”
“Not to actually grow back your arm or leg, but maybe to make a new hand or leg out of your own cells in the lab and then transplant it into you. is, of course, far in the future.”
Mating dance
The olms can live up to 100 years.
Image Jure Makovec / AFP / Getty
Given that olms are cute, don’t need to be fed, and they’ll likely outlive you, Rosa says that in the past they were sometimes given as pets to visiting dignitaries.
“Most are dead,” she added. “Olms must be kept at around 13 degrees Celsius (55 degrees Fahrenheit). If the temperature rises rapidly, say 10 degrees Celsius to 15 degrees Celsius, it kills them.”
The salamanders begin an aquatic life as olms, but then they shed their gills, develop lungs, walk on land, and become sexually mature; but olms persist and reproduce in their juvenile stage – a biological oddity like their close relative, the axolotl, also known as the Mexican walking fish.
Olms even have a mating dance.
“It goes like this,” Gnezda said. “When the female is ready, she will come to the male. When he smells her, he will start swimming in front of her; she will follow him and do a few laps together.
“At one point, the male will leave a packet of semen on the floor. He will pick it up and put it in the inner bag. When the egg is released, it will self-fertilize.”
And that’s not all.
“You can’t tell if an olm is male or female from its DNA. Both males and females have the same chromosomes. Now we are trying to distinguish the sexes by analyzing their blood and testing it. hormone ratio. It looks promising but this is still being researched.”
Dragon Hamlet
Biologist Primož Gnezda is among the scientists studying the olms.
Image Jure Makovec / AFP / Getty
Now comes the big announcement.
On January 30, 2016, a female began to feel very territorial and attacked other olms if they approached her; To the researchers’ delight, they found that she was guarding an egg.
Her teammates are immediately removed and her tank is isolated. Infrared cameras revealed that she continued to lay eggs for another eight weeks.
Gnezda said: “In the end it gave birth to 64 eggs. “In the wild, the mother mounts the eggs on rocks, as there are no real predators out there in the cave.”
“But a lot can go wrong while the eggs are developing and about two-thirds of the chicks die on their own.”
Exactly four months after the first egg was laid, the first baby dragon hatched. It darted out, fell to the bottom of the aquarium, and swam around passionately.
All 21 people survived. Interestingly, they are born with eyes that keep for a few years until skin grows over them and makes them blind.
And as of June 2021, two of those five-year-old olms are now on display.
As Gnezda revealed during a tour of the Vivarium, they are not the only unusual inhabitants of Postojna.
There are cave crickets that eat their own limbs if they cannot find food; milipedes toxic cave; winged beetles shrivel and merge on their abdomens; cave shrimp, the olms’ favorite snack; and obligate fugitive spiders – since there are no flying insects in the burrow, spiders use their silk to weave cocoons, not webs.
Speaking of food, when the olms are swept into the river by the flood, do they ever fit in someone’s plate?
Yes, said Rosa. “Until the 1980s, you could find them sold on slates in fish markets in Trieste.”
And?
“They taste like bland veal. Or so I should say.”
