Abstract
A mainly different species composition was found for the hyperbenthic family Calliopiidae in the northernmost part of the North Atlantic Ocean and the southernmost part of the Arctic Ocean, where 72 % of the species were restricted to only one side of the Greenland-Iceland-Faeroe-Ridge (GIF-Ridge). The distribution limits of the calliopiids are suggested to follow relatively sharp boundaries between water masses of dillerent origin lying on and adjacent to the GIF-Ridge or within the area on each side of the ridge, combined with the geographical barrier eftect of the ridge against dispersal of especially deep-living species. The diversity of the calliopiids was much higher north (17 species) than south (5 species) of the GIF-Ridge, showing increasing diversity with increasing latitude. The much higher diversity in the arctic waters harmonises with the knowledge of the main part of the northern hemisphere calliopiids to be arctic and subarctic species which have to cross the GIF-Ridge to get into the North Atlantic.
