現生および化石鯨骨群集 : 軟体動物を中心として

抄録

Recent whale-fall communities from lower sublittoral to bathyal sea environments have been studied in the Pacific and Atlantic Oceans. In contrast, a few fossil whale-fall communities were found from the middle Oligocene to middle Miocene deep-water deposits in Japan and Washington State, USA. It is certain that these communities have acted as dispersal stepping stones for the chemosynthetic species. On the other hand, the hypothesis that the communities acted as evolutionary stepping stones from shallow water to hot vent via cold seep site are controversial. The ecosystem around the whale-bones appeared in the Oligocene. The whale-fall communities are characterized by small mussels as Adipicola and Idas through time. However, other taxonomic composition have changed from the Oligocene to the Recent. The Oligocene communities include some articulate brachiopods and no vesicomyids, while the Miocene communities in Japan share many common genera including vesicomyids with the Recent communities, other than small limpets and other gastropods. For making clear the evolutionary change of whale-fall communities, it is necessary to find more Recent and fossil wood-fall communities as well as whale-fall communities.