Snailfish sink to new lows to extend their record as the world’s deepest fish (2023)

Scientists recently exploring some of the world’s deepest oceanic trenches in the North Pacific have redefined the known limits that fish can survive.

On 15 August 2022, a juvenile Pseudoliparis snailfish (species yet to be determined) was captured on film investigating a baited camera 8,336 m (27,349 ft) below the surface in the Izu-Ogasawara Trench off Japan. It claims the undisputed record as the world’s deepest fish.

@guinnessworldrecords Deepest fish - Pseudoliparis snailfish at 8,336 metres (27,349 ft) 🐠 #guinnessworldrecords#worldrecord#fishtok♬ original sound - Guinness World Records

The unprecedented depth – more than double the vertical extent of Mount Fuji – is approaching what is thought to be the biological bottom line for fish.

Snailfish sink to new lows to extend their record as the world’s deepest fish (1)Snailfish sink to new lows to extend their record as the world’s deepest fish (2)

Just days later, during the same expedition, two P. belyaevi snailfish were successfully retrieved from a depth of 8,022 m (26,319 ft) in the nearby Japan Trench. A watershed moment, this is the first time that any fish have been caught categorically from below 8,000 m (26,247 ft).

Snailfish sink to new lows to extend their record as the world’s deepest fish (3)

The snailfish were documented by marine biologists from the University of Western Australia (UWA) and the Tokyo University of Marine Science and Technology (TUMSAT), during a two-month survey on the research vessel DSSV Pressure Drop (since renamed Dagon). The expedition was supported by Caladan Oceanic and Inkfish, with filmmakers from the Japanese broadcaster NHK also on board.

Snailfish sink to new lows to extend their record as the world’s deepest fish (4)

The chief scientist conducting this field study was UWA Professor Alan Jamieson, founding director of the Minderoo-UWA Deep-Sea Research Centre. A consultant for GWR on deep-sea marine life, Professor Jamieson is arguably the world’s leading authority on hadal organisms – i.e., those that live deeper than 6,000 m (19,685 ft) – and has made numerous record-setting discoveries over his career.

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Snailfish sink to new lows to extend their record as the world’s deepest fish (5)

These include the deepest squid(6,212 m; 20,381 ft), the deepest octopus(6,957 m; 22,825 ft), the deepest decapod(7,703 m; 25,272 ft) and the deepest hydrozoan(10,063 m; 33,015 ft), to name just a few.

Snailfish sink to new lows to extend their record as the world’s deepest fish (6)Snailfish sink to new lows to extend their record as the world’s deepest fish (7)

Given his fathomless expertise in this area, was he surprised to find a snailfish so far down, when he himself has proposed that the absolute maximum for fish lies not much beyond this point? “The limit of 8,200 m [26,903 ft] came with the caveat of it being in the region of 8,200–8,400 m [26,903–27,559 ft] as temperature likely plays a part here,” Professor Jamieson told GWR.

“Temperature and pressure have similar perturbing effects on cells, therefore warmer waters should allow fish to go deeper.” He continued: “Two years ago, we published a paper on all ultra-deep-sea fish and concluded that the deepest is likely off Japan as the trenches there are both deep enough and slightly warmer than the previous record in the Mariana Trench. And hey presto, there it was!”

"The 8,200–8,400-m limit is pretty solid. Fish use an osmolyte in their cells that balances pressure, essentially stopping the cells imploding at depth! It is called Trimethylamine-n oxide (TMAO for short). Concentrations of TMAO increase in cells with depth and the region where it reaches isosmosis – i.e., saturation point, when they can’t put any more in – is 8,200–8,400 m" - Professor Alan Jamieson

As Professor Jamieson alludes to, this isn’t the first time that snailfish have hit the headlines for plunging to record lows in the ocean.

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Prior to this, the deepest fish on record was a Mariana snailfish (P. swirei) observed at 8,178 m (26,831 ft) in the Mariana Trench in the western Pacific on 18 May 2017. This was reported by the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) and NHK in August 2017.

This sighting came in the wake of another yet-identified snailfish species at 8,145 m (26,716 ft) – for now dubbed the “ethereal snailfish” – also in the Mariana Trench, filmed by Professor Jamieson in 2014.

Situated around 320 km (200 mi) south-west of Guam, the Mariana Trench is home to the oceans’ deepest point: the 10,935-m (35,872-ft) Challenger Deep.

It begs the question could another snailfish – or indeed a different fish species – be found even deeper still? Either in the 9,780-m (32,087-ft) Izu-Ogasawara Trench, the Mariana Trench or in another ocean trench entirely?

Snailfish sink to new lows to extend their record as the world’s deepest fish (8)

Professor Jamieson believes we are close to hitting a baseline. “Since we first started finding these snailfish around 2007–10, and the TMAO hypothesis was established (in 2014), we have done an exponentially increasing number of visits with baited cameras.

“We have now done 500 deployments of deep-sea cameras all over the world, and so our understanding of where these fish are has progressed a lot.

“Pretty much every film up to 8,336 m has fish in it, and then they simply disappear after that. We have honed into this limit in such a way that if a deeper fish is found it is likely no more than a few tens of metres, and probably then, falling within the error bars of the depth sensors. I think this might be the last significant increase in their maximum depth.”

"[After snailfish] the next deepest fish are the grenadiers (Macrouridae) and cusk eels (Ophididae), which occupy most of planet Earth, but despite such huge horizontal distributions, they pretty much drop off at a depth of around 7,200 m (23,622 ft), and usually shallower. After then, it appears to be snailfish all the way" - Professor Alan Jamieson

Certain snailfish have been able to push beyond the depth barrier of all their other kin owing to a number of special adaptations that enable them to withstand the extreme conditions. These evolutionary attributes include a largely cartilaginous skeleton and also gaps in their skulls to allow for the immense pressure, which beyond 8,000 m can exceed more than 800 times that at the surface.

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Snailfish sink to new lows to extend their record as the world’s deepest fish (9)Snailfish sink to new lows to extend their record as the world’s deepest fish (10)

However, these traits are not shared across the whole family, as Professor Jamieson explains: “There are 300 species of snailfish and most of them are shallow, even estuarine. They have percolated down into the depths during their radiating evolution and now we have a multitude of ultra-deep snailfish that live 1,000 m [3,280 ft] deeper than any quintessentially ‘deep-sea’ fish.

“It is perhaps their lack of swim-bladder, gelatinous body and efficiency in consuming small crustaceans that happen to be in the trenches, that have made them so successful.”

While the 8,336-m snailfish is garnering much of the media spotlight in terms of it fundamentally being the deepest recorded fish in history, Professor Jamieson is eager to emphasize the significance of the two P. belyaevi specimens that were collected five days later, slightly higher at 8,022 m in the Japan Trench.

Snailfish sink to new lows to extend their record as the world’s deepest fish (11)Snailfish sink to new lows to extend their record as the world’s deepest fish (12)

So how do you go about fishing at depths akin to 90% the height of Mount Everest? “We use standard fish traps from the local fishing shop, pop a bit of bait in it and tie to a $200,000 deep-sea camera,” Professor Jamieson revealed. “A lovely mix of hi-tech meets low-tech!”

He continued: “We film a significantly larger number of snailfish than we ever catch, and I am happy with that. I don’t really want to catch them; I’d rather learn as much from videoing them than having to bring them up.

“But, to know what it is, how genetically related they are to other populations, how they survive, what they eat and things like the TMAO-driven limit, we must bring up what we call ‘voucher specimens’. Normally one or two fish is enough for this type of work.”

As you might suspect given their native pitch-black habitat several kilometres below the waves, which until relatively recently has been out of reach to humans, the record for the deepest fish has had a complex and at times controversial history. A few past contenders have been thrown into doubt as more light is cast on the hadal world thanks to advances in technology and the dedicated research of explorer-scientists like Professor Jamieson.

One such of these was the so-called “Trieste flatfish”. It was reported on the ocean floor in the Mariana Trench by the Swiss oceanographer Jacques Piccard, who along with pilot Don Walsh (USA) performed the first crewed dive to the Challenger Deep in the Trieste bathyscaphe on 23 January 1960.

This account of a “flatfish” (never published scientifically) was widely questioned at the time as being a misidentification, and it’s now generally believed that the creature Piccard observed was more likely to have been a holothurian (sea cucumber).

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Another more recent contender has proven more debated. In the scientific literature, it was long thought that the deepest fish was a cusk eel of the species Abyssobrotula galatheae. A specimen was reportedly collected from 8,370 m (27,460 ft) in the Puerto Rico Trench – the deepest point in the Atlantic Ocean – by the RV John Elliott Pillsbury in 1970. This is, of course, even deeper than the newly documented snailfish at 8,336 m.

Snailfish sink to new lows to extend their record as the world’s deepest fish (13)

However, the key bone of contention here is that the cusk eel was trawled and so not observed or filmed in situ at that depth. Therefore, there’s every chance it was ensnared when the net was being lowered or lifted at some point between the sea floor and the surface.

This explanation is bolstered by the fact that there have been no other sightings of these cusk eels at such extreme depths in the 50-plus years since. Furthermore, this species is reasonably well documented, and known to be more common in the ocean’s abyssal zone – i.e., 3,000–6,000 m (9,843–19,685 ft) – and typically seen swimming thousands of metres above the seafloor.

By comparison, the deepest cusk eel to have been recorded in situ are examples of Bassozetus recorded at 7,176 m (24,543 ft) in the Indian Ocean's Java Trench. This discovery too was made by Professor Jamieson, as reported in Deep Sea Research Part I in Dec 2021.

All images courtesy of: Alan Jamieson / Minderoo-UWA Deep-Sea Research Centre / Caladan Oceanic / Inkfish

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Snailfish sink to new lows to extend their record as the world’s deepest fish? ›

On 15 August 2022, a juvenile Pseudoliparis snailfish (species yet to be determined) was captured on film investigating a baited camera 8,336 m (27,349 ft) below the surface in the Izu-Ogasawara Trench off Japan. It claims the undisputed record as the world's deepest fish.

What is the deepest snailfish ever found? ›

In 2017, the Mariana snailfish was found at 8,178 metres while another undescribed species was discovered at 8,145 metres.

What is world's deepest fish? ›

Scientists exploring a marine trench near Japan were astonished to find a fish in one of the deepest parts of the ocean, at 8,336 meters (about five miles) below the surface. The tadpole-shaped, translucent creature is a type of snailfish, and it's probably the deepest fish anyone will ever find.

How deep can a snailfish go? ›

Snailfish habitats vary widely. They are found in oceans worldwide, ranging from shallow intertidal zones to depths of slightly more than 8,330 m (27,330 ft). This is a wider depth range than any other family of fish. It has been found that they travel from the abyssal to the hadal zone over their lifetime.

How do snailfish adapt to the deep sea? ›

Hadal snailfish have a few special adaptations that allow them to survive in such harsh conditions. First, unlike other shallow-dwelling fish species, they lack a swim bladder. Where others use a swim bladder to move up and down in the water column, in the deep sea it becomes a liability under pressure.

What is special about the Mariana snailfish? ›

Scientists discovered the Mariana snailfish, the deepest ocean dweller on record, at a depth of 26,716 feet. Snailfish don't have scales. They have loose, thin skin and tiny eyes because the bottom of the sea is extremely dark.

What is the deepest sea creature ever? ›

Snailfish are tadpole-like and can only grow to about 12 inches long. They are found in oceans across the world, with some species inhabiting relatively shallow waters. The snailfish discovered 8,300 meters down — which is more than 27,000 feet, or five miles, deep — belongs to an unknown species, scientists said.

What is the new fish found in the deep-sea? ›

The newly identified species, Pyrolycus jaco, is the first fish species to be described from the hydrothermal seep site known as Jacó Scar, located on the Pacific margin of Costa Rica.

What are some facts about snailfish? ›

Snailfish: It is a deep-sea species that is also known as a sea snail. The known species of snailfish number over 400, and their sizes vary from a few centimetres to almost a metre. They have loose, scaleless skin that can occasionally be prickly and are elongated, squishy, tadpole-shaped fish.

How do snailfish adapt to the hadal zone? ›

The snailfish carries extra genes for DNA repair, which may help keep its genome intact under high pressures. It also has five copies of a gene for an enzyme that takes a compound produced by bacteria in its gut and transforms it into one that stabilizes the structure of proteins under high hydrostatic pressure.

How do fish survive in the deepest part of the ocean? ›

How the world's deepest fish survives bone-crushing pressure. Unique anatomical structures, proteins, and cell membranes allows them to withstand crushing pressure and darkness. This deep sea creature can withstand more water pressure than 1,600 elephants standing on its head.

Do Mariana snailfish have bones? ›

In the snailfishes, bone density appears to be related not only to depth, but to lifestyle and habitat. Our qualitative results suggest that pelagic and polar species have lower-density bones, providing an important direction for future study.

How does the Mariana snailfish survive the pressure? ›

Creatures such as giant amphipod crustaceans and the Mariana snailfish have high concentrations of organic molecules called piezolytes (the name comes from the Greek word "piezin" which means pressure), which stop their cellular membranes and proteins from being crushed under extremely high pressure.

Why don t fish get crushed in the Mariana Trench? ›

Many sea creatures are made of mostly water. Water cannot be compressed, or squeezed, by pressure like air can. This means that animals in the sea can stay safe when in the depths of the sea, as their body is balanced with the pressure around them, whereas we have air in our bodies that would be crushed.

What did they find at the bottom of the Mariana Trench? ›

Most of the plastic—a whopping 89 percent—was the type of plastic that is used once and then thrown away, like a plastic water bottle or disposable utensil. While the Mariana Trench may seem like a dark, lifeless pit, it hosts more life than you might think.

Has anyone ever been to the bottom of the Mariana Trench? ›

While thousands of climbers have successfully scaled Mount Everest, the highest point on Earth, only two people have descended to the planet's deepest point, the Challenger Deep in the Pacific Ocean's Mariana Trench.

What is the most rare deep-sea fish? ›

Summary of the 10 Rarest and Scariest Deep Sea Creatures
1Barreleye Fish
3Sea Spider
4Pacific Footballfish
6 more rows
Apr 20, 2023

What is the mystery fish in the ocean? ›

More than a century ago, in 1895, two Smithsonian scientists described a new kind of deep sea creature living at least 1000 m (3,280 ft) below the ocean's surface—a part of the ocean that we still know very little about. The scientists named their find the whalefish because of its whale-like appearance.

What adaptations allow deep sea creatures to survive in the deep ocean? ›

Other Adaptations of Deep-sea Animals

In the deep sea, animals' bodies are often transparent (such as many jellies and squids), black (such as blacksmelt fish), or even red (such as many shrimp and other squids). The absence of red light at these depths keeps them concealed from both predators and prey.

What adaptations are required to survive in the deep sea? ›

These creatures have several adaptations like compressible lungs, lung-like swim bladders, etc., to help them overcome the high water pressure in their deep-water environment.

What adaptations do fish in the deep have to help them live in their environment? ›

Many structures in fish are adaptations for their aquatic lifestyle. For example, fish have a stream-lined body that reduces water resistance while swimming. Fish have gills for “breathing” oxygen in water and fins for propelling and steering their body through water.

What is the deepest fish caught on camera? ›

Check out the deepest-swimming fish ever caught on camera The unknown snailfish species, of the genus Pseudoliparis, was recorded swimming in the Izu-Ogasawara Trench near Japan at a depth of 8,336 meters — or more than 27,000 feet down.

How are some fish adapted for very deep water? ›

Some bony fishes have 'swim bladders. ' These are gas cavities that constantly have gas pumped in or out as the fish moves up and down in the water column. This means they can make their bodies heavier if they want to go down, or lighter if they want to swim up.

Why do some fish survive the pressure of the deep ocean? ›

This is because most things living in the deep ocean are largely water and water is incompressible. Without gas-filled spaces like lungs or swim bladders, organisms in the great deep are less affected by pressure than we imagine.

What is the craziest fish found in the Mariana Trench? ›

The gelatinous snailfish has been found at depths surpassing 8,000 meters (26,200 feet), making it the deepest living fish known to science. Called the Mariana snailfish, it's been spied with the aid of remotely operated vehicles (ROVs) multiple times in the Mariana Trench.

What rare fish are in the Mariana Trench? ›

Mariana Snailfish

The Mariana Hadal Snailfish is the deepest fish species ever recovered from the Mariana Trench. Researchers caught this record-breaking fish 27,460 feet below sea level, and scientists theorize the maximum depth possible for fish is 27,900 feet.

How deep is the hadal snailfish found? ›

We wanted to find this elusive winged snailfish again to learn more about it and observe it in its natural habitat. These hadal snailfish tend to live at depths between 7,000 and 8,200 metres (“hadal” simply means anywhere below 6,000 metres), but their apparent rarity is perhaps misunderstood.

What fish was found at 27000 feet? ›

In a hostile realm of the ocean, where the pressure is over 830 times greater than on Earth's surface, scientists spotted a fish casually swimming around. No big deal. It's a curious-looking snailfish, and at 27,349 feet (8,336 meters) down, it's the deepest fish ever observed.

How big are Mariana snailfish? ›

The Mariana snailfish, as they've dubbed the species, has a translucent body reaching a length of over four inches, and looks somewhat like a overgrown tadpole.

What's at the bottom of the Mariana Trench? ›

Deep sea amoebas, shrimp-like creatures, and sea cucumbers live at the bottom of the Mariana Trench. Mariana Trench animals include xenophyophores, amphipods, and small sea cucumbers (holothurians) which all dwell at the bottom of the ocean's deepest depression.

What fish was found deepest in the ocean? ›

The deepest-ever fish has been caught on camera off Japan by scientists. Researchers using an autonomous deep-ocean vessel recorded the unknown snailfish species at a bone-crushing depth of 27,349 feet.

What fish has 3,000 species? ›

Cyprinidae is the largest and most diverse fish family and the largest vertebrate animal family in general with about 3,000 species, of which only 1,270 remain extant, divided into about 370 genera.

What is the biggest fish ever landed? ›

According to IGFA records, the largest fish ever caught was a great white shark that weighed an unbelievable 2,664 pounds (1,208.389 kg.).

What fish live at 10,000 feet? ›

The whiptail gulper lives in very deep waters of the eastern Pacific Ocean from 6500 to 10,000 feet (2000-3000 m) below the sea surface.

What is bigger than Mariana Trench? ›

The deepest place in the Atlantic is in the Puerto Rico Trench, a place called Brownson Deep at 8,378m. The expedition also confirmed the second deepest location in the Pacific, behind the Challenger Deep in the Mariana Trench. This runner-up is the Horizon Deep in the Tonga Trench with a depth of 10,816m.

Are there fish at the bottom of the Mariana Trench? ›

At the deepest point in the ocean lives a fish that is pink, slimy, and looks a bit like an oversized tadpole, up to a foot long. In the Mariana Trench—7,000 meters below the ocean's surface—these fish makes a living in total darkness and at crushing pressures that can reach 1,000 times more than at sea level.

Does anything live in the hadal zone? ›

Marine life decreases with depth, both in abundance and biomass, but there is a wide range of metazoan organisms in the hadal zone, mostly benthos, including fish, sea cucumber, bristle worms, bivalves, isopods, sea anemones, amphipods, copepods, decapod crustaceans and gastropods.


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