FEEDING BEHAVIOR OF CAPITELLA SP. I AND ITS IMPLICATIONS
Tsutsumi, H. & Taniguchi, A.
Prefectral University of Kumamoto, 3-1-100 Tsukide, Kumamoto 862, Japan
Our studies have focused on the feeding behavior of a sub-surface deposit feeding polychaete, Capitella sp. I, which is one of the most typical members of the benthic communities in organically enriched sediments. We have shown experimentally that dense patches of Capitella promote decomposition of organic matter and oxidation of reduced sulphides of the sediment, while this species requires organically enriched sediment for normal growth. This species is one of the benthic animals that can exploit abundant organic matter in the organically enriched sediments quickly, exhibiting high secondary production. We have observed and reviewed the feeding behaviour of Capitella to clarify the mechanisms that allow this species to impose such big impacts on the chemical conditions of the organically enriched sediment. In this study, we found three interesting feeding behaviors of Capitella: (1) surface deposit feeding; The worms burrow into the sediment, but often rise up to the surface and feed fresh deposits on the sediment. (2) transportation of surface sediment into the burrow (3) Blowing out mud from subsurface layers on the surface; The mechanisms are not clear, but mud of subsurface layer is often blown out on the surface by the activities of the worms. The amounts of sediment blown out by the worms are approximately twice as those of faecal pellets excreted by feeding of sediment. Thus, worms perform complex feeding activities and at least partly depend on the organic matter that deposited on the surface of the sediment as food resources. The sediment blown out on the surface is exposed to saturated dissolved oxygen in the overlying water. Oxidation of reduced sulphides and aerobic decomposition of the sediment should be markedly promoted on the surface of the sediment.