Rare Magnapinna Bigfin Squid Spotted in Northeastern Pacific Ocean

In the twilight-like darkness of the deep ocean water column, a whole ecosystem flourishes.

Life has evolved a wide range of adaptations to withstand levels of pressure, temperature and darkness that are profoundly hostile to humans.

Rare Magnapinna squid seen in the midnight zone

In newly released footage, scientists from the Monterey Bay Aquarium Research Institute (MBARI) recorded an uncommon encounter with one of its most unsettling inhabitants: a Magnapinna squid. Its unusual fins and streaming appendages emerged from the pitch-black bathypelagic, or midnight, zone.

This is the first verified observation of the elusive animal in the North-eastern Pacific Ocean.

"At first, I could only see the tips of what looked like fine tentacles, so I thought it was a jelly, but when the 'elbows' showed up on the screen, I knew this was something really special," MBARI deep-sea ecologist Olívia Soares Pereira told ScienceAlert.

"Magnapinna is one of the few, if not the only, deep-sea squid with such fine, long arms and tentacles that can bend like that."

Few creatures are as uncanny-looking as Magnapinna, better known as the bigfin squid. It inhabits only the deep ocean, where unrelenting cold, immense pressure and permanent darkness prevail beyond sunlight's reach.

The observation occurred on 7 August, in precisely these human-hostile conditions. The research team was using the remotely operated vehicle Doc Ricketts to inspect the seafloor close to Davidson Seamount, off Central California.

At 3,277 metres (10,751 feet) deep, the squid suspended itself over the muddy seabed, softly rippling its two huge fins while its eight arms and two tentacles hung beneath it. With the ROV's laser measurement system, the scientists calculated that the animal was about 1.25 metres from the top of its body to the tips of its arms.

Bigfin squid rank among the most difficult-to-find cephalopods known to science. Roughly 70 have been seen or collected, leaving major gaps in knowledge of even their most fundamental biology.

"There is actually so little that we know about bigfin squid," Soares Pereira said.

"From submersible sightings, we know they are the deepest-dwelling squids, with one seen an astonishing 6,212 meters – almost four miles – underwater. They are commonly seen hovering over the seafloor with their arms and tentacles extended. We have ideas and hypotheses about why they do that and what the 'elbow' pose is.

"We still have a lot of questions about their basic biology, like what they eat, how they capture prey, how they reproduce, and how rare they truly are."

The bigfin squid's distinctive ‘elbow’ posture

Magnapinna is a wonderfully strange creature with remarkable proportions. Its mantle is comparatively compact and squat, while exceptionally large fins sit on either side – the feature behind the name Magnapinna, meaning big fin. The squid resembles a small torpedo fitted with enormous flapping wings.

Its appendages are equally striking. As with other squid, it possesses eight arms and two tentacles. In Magnapinna, however, the difference is far less visually apparent, since both the arms and tentacles end in exceptionally long, slender filaments. These have been documented at lengths of up to several metres.

Their extraordinary length is not the only unusual feature. Its posture is stranger still. Magnapinna holds its appendages almost perpendicular to its mantle before sharply folding them at nearly right angles, creating the so-called ‘elbow’ pose.

As the squid is so rarely encountered, scientists do not know why it adopts this peculiar position.

"We still do not know what bigfin squid eat," Soares Pereira explained.

"Based on the behavior of other deep-sea squids, scientists believe they hover over the seafloor to passively capture prey that sticks to their tentacles. The 'elbow' pose could be a part of this feeding behavior, keeping the arms and tentacles extended without getting them tangled up."

A widespread but rarely encountered deep-sea squid

It is also hard to establish just how uncommon these bizarre squid truly are.

Although observations are rare, bigfin squid seem to have a broad distribution. Reports span the Atlantic, Pacific and Indian oceans, including the Gulf of Mexico, the Mid-Atlantic Ridge, Australia, Hawai'i, the Philippines, Micronesia and the Cook Islands. The latest sighting therefore does not greatly enlarge its known range.

In fact, a recent worldwide assessment of Magnapinna records indicates that appropriate habitat might cover an enormous share of the global ocean – up to 62 percent of the world's ocean area and 70 percent of its volume. Even across this vast possible range, though, the squid seems to exist at very low population densities.

"These scattered sightings make me believe they might be genuinely rare," Soares Pereira said.

"But in a space so big as the global ocean, I think it's hard for us to say for sure if they are genuinely rare or instead rarely encountered, or perhaps even a combination of both. That is why these encounters are always so special!"

This sighting was unexpected in another respect, too.

The scientists had not set out to find bigfin squid. Their expedition was investigating why Davidson Seamount is such a focal point for deep-sea life, and the team had been seeking evidence of a completely different species during this dive.

"Considering that we were specifically investigating furrows on the seafloor that we believe are made by feeding beaked whales, it's exciting to see another animal, and a rare one at that, potentially using the site for feeding too," Soares Pereira said.

Seamounts can serve as marine oases. As they rise from the deep seabed, they alter ocean currents in ways that gather nutrients and food.

Davidson Seamount lies about 130 kilometres (80 miles) south-west of Monterey and is already recognised for its ancient deep-sea coral gardens and an extraordinary deep-sea octopus nursery.

It now appears that one of the deep ocean's best-known inhabitants could also be benefiting from the resources it offers.

"The deep sea never ceases to amaze me. These sightings have given me an even greater appreciation for where I am now and for opportunities that allow me to experience things that once felt so far out of reach," Soares Pereira said.

"These rare encounters are always a reminder of why we do science and how important it is to share my passion and sense of wonder for the deep sea to help inspire the next generation of ocean explorers."

This article was fact-checked and edited by Rebecca Dyer. Although we take pride in our process, we are only human. If you notice an error, please let us know.