Postojna Things to Do Tips by JLBG Top 5 Page for this destination

The vivarium

Postojna cave is visited every day by several thousands visitors. In the mean time, the vivarium is visited by a few dozens, may be one hundred of visitors. Even if that was several hundreds, that would mean that only one out of ten visitors comes to the vivarium which is really a pity.

The vivarium presents several dozens of troglobites (= cave dwellers) ie animals that live permanently in caves, trogloxenes (= cave guests) , ie animals that dwell in caves but feed in the open and troglophiles (= cave lovers), ie animals that sometimes live in caves but also live elsewhere.

Along the generations, troglobites have adapted to cave life and have lost any pigments in their skin and usually their eyes. The masterpiece of Postojna vivarium is of course the famous Proteus (Proteus anguineus), named cave salamander or olm in English.

The Proteus is a blind amphibian. It is 15-30 cm long with two pairs of small legs. As it is not pigmented, the color of the blood shows through the skin and the body is pale pink, almost human color. This is why it is also named human fish. It has two outside gills, bright red. It lives in the cave ponds of Postojna and of most caves of the Dinaric Karst in the eastern Adriatic : Italy, Slovenia, Croatia, Bosnia-Herzegovina and Montenegro. As there is very little food in the caves, it eats neither much not often. In laboratory experiments, it has been found that it could live without food for as long as 12 years! With little food, it grows very slowly. It can live up to 100 years.

The olm was first mentioned in a book written in 1689 and was considered as a baby dragon. It has sometimes been represented with wings, corresponding to the gills. It was first scientifically studied and described in 1768 when an Austrian scientist, Josephus Nicolaus Laurenti gave it the name of Proteus anguineus.

The olm has been protected since 1922. It is now on the list of rare and endangered species. The caves where live the olm are protected under the rules of the Natura 2000 network. It is forbidden to collect and sell them. They can be picked only for controlled scientific purposes. Some olms have been introduced for studies in caves for example in France (Choranche and Moulis) and Belgium (Han-sur-Lesse).

More about Proteus anguinus on Istrianet web site that give several links for those interested.

It is forbidden to take any photo in the vivarium. The light is dim and not enough for a photo. Repeated flashes would harm the animals and especially the olm. This is why I have no photo of the olm.

Photo 1 is a close up on the olm painted over the entrance of the vivarium.

Photo 2 shows the entrance into the vivarium.

Mamenchisaurus

The train brings back visitors to a large room where in 2009 is held a temporary show with the skeleton of several fossil animals on display. Most of the fossils have been found in the Postojna area but some copies have been added. The Mamenchisaurus (photo) is the largest dinosaur found in Eurasia.

Cave pool

In France, these cave pools are named “gour” but I have no found any English name for them. Small stalactites are growing in a pool with a few centimeters of water. This is in this kind of ponds that live the famous Proteus anguineus (see my vivarium tip). The water is crystal clear, which means that there is very little food. This is why this creature grows very slowly

Transparent drapery

Sorry, this photo is not good (see my warning tip) but it shows an uncommon phenomenon, when a drapery is thin enough to be transparent to light. There is only on at Postojna and I missed the photo! I should have taken a tripod but let me remind that theoretically, photo is forbidden in Postojna cave!

Soda straw stalactites

Photo 1 shows what is named soda straw stalactites or vermicelli stalactites. In these stalactites, water does not flow outside the concretion but inside. They are very thin and fragile, with a hollow in the middle and thus are never very long.

Photo 2 shows soda straw stalactites that have been over flown and thus growing into usual stalactites

Photo 3: does this thin stalactite has been a vermicelli stalactite in the beginning? May be.

Now, some iron added!

The first photo shows in the background a massif almost white (pure calcite) but in the foreground, there seems that there has been chocolate dripping from the ceiling, that covers the older one. Recently (= thousand years ago!) a dripping of calcite water enriched with dissolved iron has replaced the pure calcite water, giving this rust color.

The second photo shows the same phenomenon on a drapery.

Photo 3 shows a “cupboard” with mixed columns, some white, some with the rust color of iron.

On photo 4, most of the flow is white and only in some parts are there tiny drippings of rust. The shapes on the right are named mammoth teeth.

Draperies

Photo 1: when water flows on a wall that builds draperies that cover the wall. When water brings pure calcite, the drapery is dazzling white.

Photo 2 shows a series of neighboring stalactites turning into a drapery.

Photo 3 shows that when many neighboring stalactites meet, that gives a kind of frozen cataract.

Photo 4 shows another kind of figure, there are so many!

Photo 5 show two independent neighboring columns that nearly reach the ceiling though there has not been any corresponding stalactite hanging. The one in the foreground ids almost white while the second is grayish, which means that calcite is added with manganese.

Stalactites

When water with dissolved calcite (also called aragonite) drips from the ceiling, some of it. Evaporates and calcite remains, giving a stalactite that hangs from the ceiling. More water falls on the ground and further evaporates. Calcite accumulates and build a stalactite that stands on the ground. When a stalactite and a stalagmite meet, that builds a column ? When more water flows, the column grows, building cauliflower shapes.

Photo 1 is one of these cauliflower columns

Photo 2 was taken closer and shows well the aspect of the surface and even water flowing.

Photo 3 shows another fat column but that looks more like a bundle of small columns

Photo 4 shows a stalagmite that has not yet met its stalactite. This one is looking like candle dripping.

Before the visit begins

Visitors are brought by the trains in a large cave where there are five large signs that tell the language for the visit. You must gather under the language that you choose: Slovenian, Italian, English, German and French. Several trains disembark their load of visitors. Once there are about 5-600 people, each group is taken in charge by a guide and the visit begins. This is well organized as immediately, the other groups are out of sight and out of voice.

The train

As far as 1872, a small railway was setup in the cave. Since then, it has been changed, of course. The carriages are open and made of seats for two, one behind the other. Each train can carry about a hundred. Sorry, I did not count exactly, I should have but this is my wild guess!

The train runs for 2 kilometers and bring visitors to a large room.