A Japanese-led international expedition has discovered 38 new species and identified another 28 potential new species across two of Japan’s most understudied deep-sea regions.
The Nippon Foundation–Nekton Ocean Census Expedition was undertaken in June 2025, in partnership with the Japan Agency for Marine-Earth Science and Technology (JAMSTEC), focusing on the Nankai Trough and the Shichiyo Seamount Chain.
Cold Seep Survey — Robotic arms sample biodiversity at a Nankai Trough cold seep during the Ocean Census expedition. Photo: JAMSTEC.
JAMSTEC’s research vessel Yokosuka deployed the Shinkai 6500 manned submersible, which collected over 528 specimens. All were catalogued, imaged, and preserved for future morphological and molecular analyses.
Deep-Sea Crawler — A squat lobster collected from Japan’s Nankai Trough during submersible sampling dives. Photo: JAMSTEC / Nippon Foundation–Nekton.
In October 2025, taxonomists from Japan and around the world convened at JAMSTEC Headquarters in Yokosuka for a dedicated species discovery workshop.
There they confirmed the status of these new and potentially new species and co-ordinated next steps for the publication of scientific papers, the Nippon Foundation says.
The remarkable evolutionary history of symbiotic sponge-dwelling worms, which have evolved to live in a “glass castle”, is the focus of one of the discoveries which led to the publication of research in the Zoological Journal of the Linnaean Society, led by Dr Naoto Jimi.
JAMSTEC researcher Dr Chong Chen led a comprehensive survey published in the journal Ecosphere, documenting a fivefold increase in biodiversity at cold seeps in the Nankai Trough. It documented 80 animal species, making this "the most comprehensive biological survey of the region ever undertaken".
Glass Guest — A sponge-dwelling parasite discovered during the Ocean Census expedition. Photo: JAMSTEC / Nippon Foundation–Nekton.
“The discoveries made in the Nankai Trough and the Shichiyo Seamount Chain remind us how little of our ocean has truly been explored,” Mitsuyuki Unno, Executive Director of the Nippon Foundation, has said.
By supporting missions like this, the Nippon Foundation is helping to open a new frontier of knowledge for Japan and for humanity. Each new species discovery is a step toward understanding, valuing, and ultimately safeguarding our shared ocean,” Unno said.
