Glavni izbornik

Izdvojeni sadržaji

The underground world of karst: cave fauna

 

The caves of the Dinaric karst are the richest in the world in the number of cave species of which 70% are endemic

Animals that inhabit underground areas developed from aboveground ancestors, developing adaptations suited for cave habitats over long time periods. In developing these new traits, through regressive evolution, they simultaneously lost others (loss of individual acquired traits and development of simpler morphological traits).

Some of the main adaptations to underground life are the reduction of sight organs, loss of pigment, thinning of the integument (skin), elongation of limbs, slowed metabolism, longer life, low level of reproduction, accumulation of fat reserves, reduced aggressiveness, loss of the circadian rhythm of activity, loss of seasonal changes and activities, and changes to brain function (increased avoidance of barriers and better spatial memory).

The animals found underground can be divided into:

– troglobionts on land and stygobiont in water – inhabitants of cave habitats whose entire life cycle takes place underground

– eutroglophiles on land and eustygophiles in water – inhabitants of cave habitats that can have both underground and aboveground populations, i.e. they can spend their entire life underground or above ground

– subtroglophiles on land and substygophiles in water – occasional residents of cave habitats that use caves for specific parts of their life cycle, such as hibernation, reproduction, raising young, taking shelter from inclement weather

– trogloxenes on land and stygoxenes in water – incidental residents of cave habitats.

The caves of the Dinaric karst are the richest in the world in terms of the number of cave species living within. There is virtually no island or mountain that does not have at least a few of its own endemic taxa of cave fauna. Most cave species have very limited distribution ranges, and of the known species in Croatia, nearly 70% are endemic.

Greater attention should be paid to raising awareness of this high abundance of the unique endemic cave species of the Dinaric fauna and Croatian fauna, and the need to preserve this heritage as a priceless treasure.

According to the Red Book of Cave Fauna of Croatia, 186 cave taxa are threatened in accordance with the threat criteria of the International Union for the Conservation of Nature (IUCN). One of the greatest threats is the pollution of underground habitats.

With the proclamation of the Natura 2000 ecological network, areas important for the conservation of European threatened species and habitats were defined. As such, the subterranean habitats of Croatia have been recognised as natural habitats of interest for the EU. About 400 speleological structures are listed in the category ‘Caves and pits closed to the public’ (code 8310) and 220 as ‘Submerged or partially submerged sea caves’ (code 8330). Three troglobionts are also included on the Natura 2000 list of target species: narrow-necked blind cave beetle Leptodirus hochenwarti, southern Dinaric cave bivalve Congeria kusceri and the olm Proteus anguinus, while 12 species of bats are also listed.

To date, 170 cave taxa have been recorded in the speleological structures in the area of Krka National Park, of which many are endemic to the Dinarides and to Croatia, and four are endemic to Krka National Park (stenoendemic): the snails Dalmatella sketi and Lanzaia skradinensis, the centipede Eupolybothrus cavernicolus and the springtail Verhoeffiella margusi. Recent research has collected several taxa that, upon preliminary examination, appear to be new species to science, but they have not yet been scientifically described.

Photo: Branko Jalžić