Existing research suggests that Biokovo has peculiar and diverse wildlife, although sadly insufficiently explored.
A large number of endemic species and tertiary relicts has been preserved in the Biokovo area thanks to its location in a part of Europe that was not significantly affected by the Tertiary glacial period. Regardless of the large number of researchers, the invertebrate fauna of Biokovo remains largely unknown. There has been more systematic research into earthworms, millipedes, as well as beetles such as ground beetles, butterflies and sawflies. Systematic data is available for butterflies, as well as scientific papers focusing strictly one some of these species.
One of the first researchers of the Biokovo fauna was entomologist Pierre Francois Comte Dejean, a French marshal who identified 87 species of beetles in his research in 1817. A large number of endemic species makes the subterranean fauna particularly intriguing.
Since systemic research has been done as part of the efforts to make an inventory of the park's species, we will focus a bit more on this type of fauna.
The numerous caves and pits of Biokovo are homes to fascinating subterranean fauna. For now, over 120 cave organisms have been identified, more than half of which are endemic species. Twenty five of those species can only be found on Biokovo. There is a large number of relicts, or so-called living fossils. These are creatures that lived above ground in geological eras long past, that went extinct and disappeared from their original habitat. However, some of them survived in smaller isolated areas and adapted to life under ground over the years. Their relatives have long since gone extinct or can only be found in Africa and other remote places.
Biokovo’s subterranean layer serves as a habitat both for species thriving in warm periods as well as those thriving in glacial periods.