Scientists exploring two undercharted regions of Japan's deep ocean have confirmed 38 entirely new species — and at one site alone, the known diversity of life increased fivefold. One of the newly documented creatures lives inside a sponge made of glass.
The discoveries come from a landmark 2025 expedition by the Nippon Foundation–Nekton Ocean Census and Japan's national marine research agency, JAMSTEC, published in March 2026. They offer a glimpse of just how much of the deep ocean remains unknown — and how extraordinary it is when we finally look.
**The Expedition**
In June 2025, JAMSTEC's research vessel *Yokosuka* and the manned submersible *Shinkai 6500* — capable of diving to 6,500 metres — descended into two unexplored zones: the Nankai Trough and the Shichiyo Seamount Chain, off Japan's southern coast.
Over the course of the expedition, the team collected 528 specimens. Back on the surface, taxonomists from around the world gathered at JAMSTEC headquarters that October to assess what had been brought up. By the time papers were published in March 2026, the count stood at 38 confirmed new species, with 28 more candidates still under review.
The expedition was part of the Ocean Census — a global initiative launched in 2023 to catalogue the full breadth of ocean life within a generation.
**The Fivefold Leap**
Perhaps the most striking finding involves the cold seeps of the Nankai Trough — places on the seafloor where methane and hydrogen sulphide seep up through cracks in the rock, sustaining strange communities of organisms that live entirely without sunlight, powered by chemical energy rather than photosynthesis.
Before this expedition, scientists knew of 14 animal species living at the Nankai Trough's cold seeps. After it, that number stands at 80 — a fivefold increase from a single survey.
The newly documented species span an extraordinary range: molluscs, annelid worms, arthropods, echinoderms, cnidarians, nemerteans, and a bryozoan. This is not a narrow ecological community — it is a complex, diverse world operating independently of the sun.
> "These discoveries highlight how little of the ocean has been explored, and contribute to opening a new frontier of knowledge for humanity." > — Mitsuyuki Unno, Executive Director, The Nippon Foundation
**The Glass Castle Worm**
Among the new species, one stands out for its setting. In the Shichiyo Seamount Chain, researchers found a worm living inside a glass sponge — a sponge whose skeleton is made of silica, forming a latticed structure of biological glass. The worm had made its home inside a glass castle on the seafloor, a thousand metres beneath the surface.
This kind of discovery is a reminder that even our framework for understanding what "normal life" looks like may be too narrow. In the deep ocean, biology finds solutions to survival that have no parallel on land or in shallower waters.
**Why the Ocean Remains So Unknown**
The deep ocean — below 200 metres — covers more than half the planet's surface and constitutes roughly 95% of all habitable space on Earth. Yet only a small fraction has been observed directly. Submersibles are expensive; expeditions are logistically complex; taxonomy takes time.
The Ocean Census is attempting to change that at scale — bringing together research institutions from across the world to systematically map ocean biodiversity before it can be threatened by climate change or deep-sea mining.
Finding 38 new species in two sites in a single expedition suggests the work is only beginning.
**What Comes Next**
Naming new species is only the start. Researchers must now understand the ecology of these creatures, how they interact with each other, and what their biology tells us. Papers on the newly confirmed species are being published in stages through 2026.
The 28 candidate species still under taxonomic review may push the final count even higher.
In the meantime, the Nankai Trough — a cold, dark, methane-fed world now 80 species strong — remains one of the most remarkable places on the planet we call home. 🌊🔬
*Sources: Nippon Foundation–Nekton Ocean Census / JAMSTEC, published in Ecosphere (Dr. Chong Chen). Oceanographic Magazine, IFLScience, Ocean Census press release, Astrobiology.com (March 2026)*
