Geopark's fauna is rich and diverse. This whole area is a treasure chest of a large number of endemic species. The mountain's fauna is also very diverse, especially in its subterranean caves. Wolf and the wild boar call the mountain their home, as well as wild mouflon sheep and chamois goat, present in large numbers on Biokovo since it was reintroduced back in 1964. The chamois' incredibly quick adaptation to Biokovo's landscape is proof of it being native to this habitat. The preliminary analysis of this fauna sets Biokovo apart as a "hotspot" of biological diversity of Croatia and Europe, especially with its subterranean fauna. However, further research is needed. The subterranean fauna is one of the most pronounced elements of fauna in this mountainous part of Geopark.. There are currently more than 180 identified species in the caves, 60 of which are endemic to Biokovo. This area is also inhabited by large butterfly populations, as many as 400 species. The amphibians on Biokovo include 5 species of frogs, large-sized salamanders and alpine newts found in shallow water. There are 21 reptilian species, of which tortoises are becoming increasingly rare. Among the almost 100 bird species there are a large number of endangered ones in Croatia. The Alpine chough is especially interesting because it builds its nests in pits, and this provides clues to speleologists while searching for new pits. There are 42 species of mammals in this mountainous region. On the other end of Geopark, in the hinterland, there is an incredible variety and diversity of endemic subterranean fauna. The Red Lake and Vrljika River are home to endangered species (NATURA 2000) such as the spotted minnow (Cro. Imotska gaovica, Lat. Delminichthys adspersus), the spined loach (Cro. ilirski vijun, Lat. Cobitis illyrica), the soft-muzzled trout (Cro. mekousna pastrva, Lat. Salmothy-mus obtusirostris) , the white-clawed freshwater crayfish (Cro. bjelonogi rak, Lat. Austropotamobius pallipes) and others.