It would seem that for a macro photographer who mainly enjoys photographing insects, the period with continuous snow cover and long-term outdoor temperatures below the freezing point is a kind of “silly season”. There are several ways out. Every photographer’s computer contains a large amount of unprocessed material (those who deal with composite photography know what we are talking about). Long winter evenings are the right time to process them. Or at least smear photos that do not pass the author’s strict selection. Another option is to move to more southerly areas, where there are more favorable meteorological conditions for photographing small animals, which is conditioned by sufficient free time and financial resources. Since I am lucky enough to live in the Bohemian Paradise at the foot of the Prachovské skaly, I found yet another solution.

The caves in Prachovské skály are part of a geomorphologically very varied pseudokarst relief developed in upper cretaceous block sandstones, through which tectonic disturbances penetrate. The typology of pseudokarst caves divides caves of sandstone relief into several groups. Various types of caves are represented in Prachovské skály, e.g. fissure caves, layered caves, cave niches. However, caves of the scree and combined type (e.g. fissure-stratified, fissure-fissure or fissure-scrub) dominate here.

Just for explanation. All geological formations referred to as pseudokarst are formations formed in non-karst rocks. Karsts are exclusively limestone. The word karst is an anagram of the Italian word Carsus, which is the name for the limestone mountain massif on the border between Slovenia and Italy (the Dinaric Mountains). The name of this region gave rise to the general geological term karst.
The conditions in underground spaces, especially in the shallow ones, are not completely constant. However, fluctuations in temperature, humidity and light are not as extreme here as on the surface. It is no different in the sluices and caves in the Prachovské skaly. A number of invertebrates therefore found relatively constant conditions here, to which they adapted despite the very modest food supply. And not only invertebrates.

It is not necessary to look for life manifestations here in any complicated way. Even with a cursory glance at the rock walls and ceilings of the caves, we discover their inhabitants. One of the most striking are the relatively large spiders of the European cave spider (Meta menardi). They prefer to stay on the ceiling of underground spaces together with their conspicuous cocoons, which seem to be spun from silk. A much smaller representative of the spider kingdom is the Comb-footed cellar spider (Nesticus cellulanus). Both species of spiders have perfectly adapted to the eternal cold and darkness of this underground realm.

The stability of the conditions of this environment is certainly an advantage. But what do these spiders eat? Not too many prey fly in the dark and damp. Although both species build small nets, they are more like a shelter or a place to store cocoons. They usually look for prey on the walls of their underground shelter. Upon closer inspection, some potential spider prey will indeed appear.

One of the most lively potential spider snacks is the Common centipede (Lithobius forficatus). Regardless of the temperatures slightly below freezing, she ran quite briskly along the frozen rock face in places. Only a little slower was a three millimeter representative of beetles, probably of the genus Aphthona. The most likely, and I dare to guess, even the juiciest morsel for spiders are represented by representatives of two different groups. The first one is the last generation of hibernating females of the Common house mosquito (Culex pipiens). The other one is the beautifully colored murres of the Herald  (Scoliopteryx libatrix). Both groups are apparently affected by the cold more noticeably, as they sit motionless on the walls of the caves and do not allow themselves to be disturbed in any way. Cellars often winter in larger aggregations.

Larger or smaller aggregations, colonies, are also created by their potential predators. Now, in the winter, they anticipate the winter together and neighborly just a few meters from each other. Various types of bats hibernate near the ceiling of many caves. I noticed two during my visit. The Greater horseshoe bat (Rhinolophus ferrumequinum) is a large species of bat whose membranes have a purplish tinge in the visible spectrum. The Barbastelle bat (Barbastella barbastellus) is a medium-sized species.

If we direct our gaze from the ceilings of the cave to its bottom, many of us may be surprised by mysterious formations. They are permanently wet, water is constantly dripping from the ceiling of the cave. And water is the condition for their creation. Root stalactites, as these formations are called, are alive. They arise mainly in sandstone pseudokarst spaces, into which tree roots reach from the surface of the earth. Drops from the ceiling of the cave are a “go for the water” signal for the root hairs. And so the tiny roots, despite gravity, do not grow into the ground, but upwards. Spruce trees, birches, and probably other types of trees do this commonly. The largest root stalactites reach up to 70 centimeters. Their age can be 50 to 100 years. The length of their life depends on their tree. Since they are part of it, they disappear with the demise of the tree.

I had a very rare opportunity to look into this underground realm. These places are hidden from the common visitor. And it’s good. This world is not only dark and mysterious, but also very fragile.