How does a fish live eight kilometres beneath the surface, under pressure equal to a thousand cars stacked on its back, in water so cold and so heavy that the proteins in its body should long since have stopped folding? - Space Daily

What the report says

Space Daily reported on the biology behind hadal snailfish, focusing on observations made in August 2022 in deep trenches south of Japan. A baited camera in the Izu-Ogasawara Trench filmed a juvenile snailfish at 8,336 metres, described later in Deep-Sea Research Part I as the deepest confirmed video record of any fish. Days afterward, two Pseudoliparis belyaevi were collected at 8,022 metres in the nearby Japan Trench, marking the first physical recovery of fish from below eight kilometres.

At those depths, the article notes, pressure is about 84 megapascals, or more than 800 times sea-level atmospheric pressure. Space Daily cautions that popular comparisons to “a thousand cars” are only illustrative, because the pressure comes from all directions rather than a weight resting on the animal. The snailfish survives partly because its watery tissues remain close to the same pressure as the surrounding seawater and it lacks a gas-filled swim bladder that would be vulnerable under such conditions.

The report emphasizes that softness alone does not explain survival. Hadal snailfish have pale, gelatinous bodies, thin muscle and lightly mineralized skeletons, but their enzymes, nerves, membranes and genetic machinery must also function under extreme cold and pressure.

A key molecular factor discussed is trimethylamine N-oxide, or TMAO, an osmolyte found in marine animals that becomes more concentrated in deeper-living fish and helps maintain protein function. Space Daily also cites research on pressure-tolerant enzymes and genome-level adaptations, presenting the snailfish as an example of survival achieved through many coordinated changes rather than one protective trait.