The Snailfish That Lives in the Deepest Part of the Ocean

Life Where No Light Reaches

The Mariana Trench is the deepest known place on Earth, plunging over 11,000 meters beneath the ocean surface. It’s a world without sunlight, with crushing pressure that would flatten a submarine like a soda can. Temperatures hover just above freezing, and food is scarce.

It seems impossible for any animal to survive here.

But one fish does.

Meet Pseudoliparis swirei—the snailfish that lives deeper than any other known fish on the planet.

Discovery in the Darkness

In 2014 and 2017, marine scientists exploring the Hadal Zone—depths below 6,000 meters—captured footage and specimens of a strange, soft-bodied fish living at over 8,000 meters deep.

This was a game-changer.

It was the first fish ever recorded alive at such a depth. While other species have been suspected to live in the deep, none had ever been directly observed or caught below that mark.

The new species was officially named Pseudoliparis swirei, after Herbert Swire, a crew member of the HMS Challenger—the first ship to explore the trench in the 1870s.

Why "Snailfish"?

Snailfish get their name because their bodies are soft, slippery, and scaleless—a bit like a sea snail without a shell.

But they’re not helpless.

These fish are highly specialized for the deep sea. Pseudoliparis swirei, in particular, has adapted to an extreme environment in ways that are still being studied.

Despite living in total darkness, they don’t have huge eyes like some deep-sea fish. In fact, their eyes are reduced, since there's nothing to see at that depth anyway.

They also lack a swim bladder—a gas-filled organ most fish use to control buoyancy—because gas sacs collapse under deep pressure. Instead, snailfish have gelatinous bodies that help them float naturally in the water column.

How Do They Survive the Pressure?

At 8,000 meters deep, the pressure is over 800 times greater than at sea level.

That’s like having 50 jumbo jets stacked on top of your head.

So how does this fish avoid being crushed?

The answer lies in its biochemistry and body structure. Pseudoliparis swirei has:

• Soft cartilage instead of hard bones, which reduces structural stress

• Gel-like flesh that resists compression

• Special proteins that stabilize its enzymes and cells under high pressure

• Unique osmolytes (molecules in cells) that help maintain cell function in extreme pressure

These adaptations allow the fish’s body to maintain shape, energy, and balance—without being destroyed by the crushing force around it.

What Do They Eat?

Food is extremely limited in the hadal zone. There are no plants, no algae, no photosynthesis.

So what’s on the menu?

Snailfish feed on tiny crustaceans like amphipods and isopods. These creatures fall from higher in the ocean as part of what’s called “marine snow”—a slow rain of organic matter, including dead plankton, fecal pellets, and decomposing animals.

Pseudoliparis swirei uses its suction-feeding mouth to vacuum up prey from the sediment or water column. Their jaws are surprisingly powerful for such a squishy body.

A Community Few Know Exists

Though they live in the deepest ocean, Pseudoliparis swirei doesn’t live in total isolation. There’s a whole ecosystem in the Mariana Trench—made up of shrimp, worms, bacteria, and other extremophiles.

These creatures interact in a slow-motion dance of survival, where everything is adapted to low temperatures, high pressure, and limited food.

The snailfish is one of the top predators in this system—not because it’s fierce, but because there’s simply so little competition at that depth.

Why the Deepest Matters

The discovery of Pseudoliparis swirei changed how scientists view ocean life.

For a long time, it was believed that no complex vertebrate could live beyond 8,000 meters. But this fish proves otherwise. It has shown that life can adapt far beyond our expectations.

Its genome is now being studied to learn how proteins, cell membranes, and DNA survive under such stress. This could have applications in medicine, deep-sea exploration, and even space biology.

Because if life can exist here—under crushing pressure, in pitch blackness, without oxygen-rich water or sunlight—then maybe it can exist in places like Europa or Enceladus, icy moons with oceans hidden beneath the surface.

A Fish That Redefines Limits

The snailfish isn’t beautiful by traditional standards. It doesn’t glow. It doesn’t hunt in dramatic ways. It doesn’t have teeth like daggers or a deadly sting.

But it is quietly extraordinary.

It thrives where few other animals even dare to venture.

It survives in the dark, alone, at the bottom of Earth’s deepest scar.

And it does so not with brute strength—but with adaptation, softness, and resilience.