Scientists Went 31,000 Feet Below Pacific Ocean And Noticed a Hidden World Never Seen Before

Between July 7 and August 18 this year, some scientists hopped inside the little titanium capsule of Fendouzhe and ventured on an otherworldly journey. Fendouzhe descended to a depth that was deeper than the one where the Titanic was found. 31,000 feet, to be precise. Its robot arms drilled into the seafloor and scooped out wet sediment, storing the samples in its biological box and slurp sampler. All the while, the experts sitting inside gazed at the mysterious underwater world. In a study published in the journal Nature, they documented the details they captured during this fascinating voyage.

In such depths, where pressure is so intense that it could crush a diamond, a surprisingly whole new world of mysterious creatures was thriving. All thanks to Fendouzhe, the first manned submersible from China that can penetrate extreme depths inside oceans and uncover secrets about the dark world down there. With high-definition cameras equipped in its green-white body, a sharp laser beam mechanism, and sonar ears, the vessel is currently the only one capable of taking humans to such extreme depths.

Once the samples were collected from the deep-sea during this expedition, they were immediately transported to the shipboard laboratory. In the lab, they were sorted into groups based on different levels, using visual inspection or under stereomicroscopes. Each sediment sample was stowed away inside gas-tight glass vials. The tiny organisms and microbes lurking inside the sediment were trapped, too. Each of them was counted, denatured, preserved, and cooled in formaldehyde solution. Meanwhile, the footage recorded was analyzed for nano-scopic details.

The study was conducted by scientists from the Chinese Academy of Sciences in the Northwest Pacific Ocean. Also known as "hadal trenches,” this site is one of the most volcanically and seismically active zones in the deep ocean. The Hadal zone, according to a report in Progress in Oceanography, is where the water’s depths increase 6,000 metres, and where shallower marine environments, abyssal zones, and V-shaped trenches serve as natural traps. This particular expedition was conducted at the Kuril–Kamchatka Trench and the western Aleutian Trench, a location infamous for its mischievous plate tectonics.

While the tectonic plates shake, the fissures and cracks scarred into the seafloor let out methane-rich fluids. These fluids spill and dribble through the faults running through the deep-sediment trenches. Communities of hungry microbes residing in these hydrothermal vents and cold seeps derive their sugars from chemical reactions in a process called “chemosynthesis.” The team investigating the hadal trench for this study came across a fascinating, mysterious world of creatures ranging from tubeworms to sea cucumbers and colonies of centipede-like critters. 

Overall, they managed to identify 7,564 species of prokaryotic microorganisms, over 89 percent of which had never been seen before. Laboratory analysis revealed that these chemosynthesis-based communities are capable of thriving in one of the most extreme conditions on the planet. The study also improved their understanding of how the carbon cycle works in an environment dominated by utter darkness. “The communities, typically dominated by Bivalvia and Siboglinidae, and sustained by microbial chemosynthesis, are confined to areas where fluids rich in hydrogen sulfide and/or methane are released through geological fractures,” the researchers noted in the paper. 

The mysterious world was invaded by white free-moving polychaetes, clusters of frenulate siboglinids with red tentacles, clam beds, white microbial mats, tube-dwelling creatures in black sediments, dark blue muds, snow-like microbial mats, and tubeworms. Another valuable insight came from the examination of gases in cold seeps, phytoplankton blooms, and sediments of pushcores. These provided amazing clues to the microbial origin of life as well as the knowledge about the boundaries, strategies, and interactions happening among the creatures lurking in these dark depths.

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