Carnivorous sponges, slug fish, scavenging crustaceans… but also human waste. This is what an international team of researchers discovered by probing the abyss of the Pacific, diving to a depth of almost ten kilometers off the coast of Japan. In two months of expedition, scientists have cataloged no less than 108 distinct groups of organisms and a still mysterious marine creature, which seems to have never been observed before.
It is into the Ryukyu and Izu-Ogasawara trenches, which reach depths of approximately 7,900 and 9,800 meters respectively, that a team set up by the Minderoo-UWA Deep Water Research Center of the University of Western Australia and the Tokyo University of Marine Science and Technology ventured in 2022 to explore the biodiversity of the abyss.
Usually, researchers use trawling techniques to bring samples of specimens living in the deep ocean to the surface of the sea, which is not without consequences for the organisms captured, which are often damaged during these operations, explains IFL Sciences. However, this destructive practice provides little information on their behavior.
However, for this expedition, the researchers boarded the DSSV Pressure Dropa ship equipped with a small submersible used during oceanographic missions, which allowed them to directly study deep-sea animals in their natural habitat.
@pensoft.publishers 😯Fascinating new #study recorded 108 morphotaxa from 4,500m down to the #hadal depths of 9,775m, revealing the hidden life of the NW Pacific trenches. 🎥They analyzed 460 hours of video from landers & submersibles across the Japan, Ryukyu, and Izu-Ogasawara trenches. 👇Full study here: https://doi.org/10.3897 /BDJ.14.e182172 📗You can read all about it on Pensoft’s blog 👇 https://blog.pensoft.net/2026/04/06/what-lives-10-km-below-the-surface-a-new-look-at-life-in-japans-deepest-ocean-trenches/ Research center: Minderoo-UWA Deep-Sea Research Centre. Main funders of the expedition: Inkfish, Caladan Oceanic #deepsea #sciencetok #research ♬ THE MOON – Camargguinho
A new species?
“This allowed us to establish the most comprehensive visual database to date for abyssal and hadal megafauna (beyond 6,000 meters depth, editor’s note) of the Pacific Northwest”explained the team in a press release.
Arriving at a depth of 9,137 meters, it is a creature never before seen, moving slowly and currently designated as Animalia incertae sedisaccording to the taxonomy required for species with uncertain identity, which researchers were able to observe twice: presenting characteristics close to nudibranchs (also called “sea slugs”) or sea cucumbers, the species still remains unidentified.
At a further 600 meters depth, impressive crinoids – marine animals resembling algae but with a calcareous skeleton – were observed, not far from carnivorous sponges belonging to the family of Cladorhizidaethe deepest ever seen to date.
Beyond the different species recorded, the researchers’ analyzes helped reveal how geological processes, depth and the availability of nutrients from surface waters shape life in these abyss environments.
“While it is easy to imagine the abyssal trenches as wild and untouched spaces, our results also highlighted the presence of debris of human origin, probably transported by subduction processes”explained the team.
