Intestinal helminth communities of the long-finned pilot whale (Globicephala melas) off the Faroe Islands.

The intestines of 170 long-finned pilot whales, Globicephala melas, caught off the Faroe Islands (N.E. Atlantic) were examined for helminth parasites. Eight species were detected but only 4 occurred in at least 10% of the sample. No core or recurrent group of species were identified and no correlations between abundances of species were significant. Diversity values were far below those reported for other endotherms. Colonization by helminths was random, whales not being readily colonized. These features point to largely unpredictable, isolationist infracommunities, there being little potential for inter-specific interactions. Older hosts tended to harbour more diverse infracommunities, offering more opportunities for such interactions. Two hypotheses, which might also apply to other cetaceans, are proposed to account for the depauperate helminth communities of the pilot whale: (i) some ancestral helminth species failed to adapt their cycles to the marine habitat and (ii) the hosts' isolation from land prohibited new infections with helminths of mammals.