An international effort to document life in Japan’s deep ocean has confirmed the discovery of 38 new species, following an expedition by the Nippon–Nekton Ocean Census Foundation and the Japan Agency for Marine and Earth Science and Technology (JAMSTEC).
The June 2025 mission, conducted aboard the research vessel Yokosuka and the manned submersible Shinkai 6500, collected more than 528 specimens. In October 2025, taxonomists from around the world gathered at JAMSTEC headquarters for a species discovery workshop to verify these findings and coordinate their scientific publication.
Among these discoveries are two revolutionary studies: exhaustive research published in the journal Ecosphere, led by JAMSTEC researcher Dr. Chong Chen, which reveals a five-fold increase in known biodiversity in the cold seeps of the Nankai Trench; and research published in The Zoological Journal of the Linnean Societydirected by Dr. Naoto Jimi, which demonstrates the remarkable evolutionary history of symbiotic sponge-dwelling worms, which have evolved to live in a protected environment.
In the Shichiyo seamount chain—a series of deep-sea volcanic peaks located 500 to 700 km southeast of Tokyo—researchers discovered an intricate biological relationship within glass sponges.
These sponges build silica skeletons, creating a rigid, translucent habitat. Two new species of polychaete worms—Dalhousiella yabukii and Leocratides watanabeae—were found living symbiotically within these structures.
The dives at the previously virtually unexplored Shichiyo Seamount also revealed: Five new species of dwarf lobsters, including the genus Munidopsis; new species of marine life, such as octocorals, nemertines, amphipods and kinorhynchs and the expansion of the range of several species that were previously considered rare or absent in Japanese waters.
