Baby dragons in Postojna cave, Slovenia

I’ve visited quite a few famous caves in the U.S., but the amazing caverns carved from karst limestone near Postojna in southwestern Slovenia are the most spectacular I’ve ever seen. They are definitely one of the Wonders of the Natural World.

We walked over the Pivka river bridge and uphill to the cave. This is the river that carved the caverns millions of years ago.
From this unassuming entrance a complex of caverns and passageways runs 24 kilometers (14.4 miles) underground. There are actually four caves, interconnected by the Pivka river, which drains through them.
5 km of the cave is open to the public, the first 3.5 of which is covered by train. The rail system was first installed in 1872, and electric lighting shortly after that. The cave became a tourist destination as early as 1819 with Archduke Ferdinand’s visit, but the cave has graffiti dating to the 1200s!
We followed a very well maintained path up and down through numerous passageways and huge ballrooms over a 1.5 km track to view a huge variety of cave formations. One such ballroom is noted for its exceptional acoustics and is so large it can hold 10,000 people. Symphony orchestras sometimes perform there.
Some of the massive rooms were several stories tall, decorated with all shapes, sizes, colors, and varieties of cave structures. The bridge in this photo was constructed by Russian POWs during WW1.
This is not an effect of multiple colored lights on the cave structures, but are multi-colored columns of stalactites and stalagmites that have fused together over centuries as mineral-laden water seeped through the porous limestone.
Pale white formations are pure calcium carbonate, and darker stained formations have manganese in them.
I thought this collection of stalagmites looked like little people.
A pure white column (called “the Brilliant”) stands right next to a chocolate brown column with thin rods that have gradually fused together. It’s fascinating to think about how the water must have dripped through here to create these shapes.

The Postojna cave system is notable because of all the animal life found there. Over 100 species have managed to survive in the dark, cold (45-50 F), mineral-rich water, including a cave beetle species, a jelly fish relative, crustaceans, pseudo scorpions, and a cave spider species. But the largest and most remarkable cave dweller in Postojna cave is the “baby dragon” or cave salamander or Olm (Proteus anguinus).

The Olm reaches 8-12 inches in length, with a worm-like body, feeble forelegs, and a short tail. It has bright pink, frilly external gills, and basically resembles the aquatic, larval stage of salamanders even when sexually mature (a condition called neoteny). They are completely blind (eyes covered by skin) but have sound and vibration detectors in their elongate head, as well as smell and taste receptors in their nose that help them find prey. (Photo from CNN travel, Dec 2021)

There was some excitement among the cave biologists several years ago when one of the large Olms began to lay eggs. It took quite a while but she eventually laid more than 50 eggs, about 20 of which hatched in about 5 months. The youngsters had normal eyes, but they regressed in size and skin eventually grew over them. When presented with small worms, Olms immediately go on the attack, hoovering them up (like a vacuum cleaner) with their elongate snout.

Photos of a few of other inhabitants of Postojna cave, from CNN travel, Dec, 2021.