Eight species of cetaceans are considered regular inhabitants of the western Mediterranean basin.

Species considered as common or regular are: common bottlenose dolphin (Tursiops truncatus), short-beaked common dolphin (Delphinus delphis), striped dolphin (Stenella coeruleoalba), Risso’s dolphin (Grampus griseus), fin whale (Balaenoptera physalus), sperm whale (Physeter macrocephalus), Cuvier’s beaked whale (Ziphius cavirostris) and long-finned pilot whale (Globicephala melas).

On the basis of studies comparing DNA, these species are considered genetically distinct from the same species occurring in the north-east Atlantic Ocean.