Torishima Whale Bone Deep-sea Animal Community Assemblage

Abstract

A deep-sea animal community crowded around whale bones was found near the summit of the Torishima Seamount during the submersible Shinkai 6500 cruise of Japan Marine Science and Technology Center (JAMSTEC). The Torishima Seamount, east of Torishima Island, about 550 km south off Tokyo, is tectonically situated in forearc of the Izu-Ogasawara (Bonin) arc-trench system. The focus of Shinkai 6500 dives was on forearc seamounts of the system, where serpentinite was recovered at the time of Leg 125 of the Ocean Drilling Program. The deep-sea animal community, therefrom, offers some significant insight on origin of deep-sea ones. Deep sea animal communities have hitherto known along the oceanic ridge system and from the landward slopes of the subduction zones. The former is a hydrothermal vent community in divergent plate boundary. whereas the latter is cold seep community in convergent plate boundary. Another quite rare type of chemosynthetic animal community, life of which supported by nutrition of lipid seepage from sunken whale bones, was found in the Santa Catalina Basin, west of the United States. The deep-sea animal community from the Torishima Seamount is biologically similar to the last one in depending on nutrition of whale bones. The whale bones was discovered as white cubic materials on the way to the summit of the Torishima Seamount during the dive #148 of Shinkai 6500. The white cubic stuffs were linealy distributed and were together with various kind of deep-sea animals such as shrimps, sea urchins, star fish, vivalves, worms, and gastropods. Such different type of queer animal community were recorded by video movie and photographs, and specimen of the whale bones was collected.