Life can be very diverse, and sometimes, outright weird. When you get to the vast depths of the ocean, that’s doubly true. To adapt to the frigid, high-pressure, and dark environment of the deep sea, many creatures have undergone special adaptations that allow them to survive.
The magnapinna squid (or bigfin squid) is one of these creatures. With its alien physical appearance and ghostly long, thin tentacles, it’s quite a sight to behold.
This ethereal creature is called the magnapinna squid or the bigfin squid. True to its name (‘magna’ means ‘great’ and ‘pinna’ is the external part of the ear), these cephalopods have undulating heart-shaped fins that are much larger than its body, as well as extremely long arms and tentacle filaments measuring 11 times longer than their body length.
All in all, the squid can measure 26 feet (8 meters) in length, and remarkably, its arms and its tentacles are the same length and look identical — this is unlike any squid or octopus that lives today, and has only been observed in extinct creatures called belemnites.
The difference between arms and tentacles is that arms have a line of suckers going down the entire length, whereas tentacles don’t have suckers until you get to the tentacular clubs. With a few exceptions, octopuses have eight arms and no tentacles, while squid and cuttlefish have eight arms (or two “legs” and six “arms”) and two tentacles.
Dr. Mike Vecchione, the curator of the Smithsonian National Museum of Natural History and leading authority on squids, explained that in most cases squids use their arms and tentacles for different purposes but this does not apply for bigfin squids. Researchers assume that they use their tentacles and arms for the same goal — feeding. Their sticky spaghetti-like appendages act like a net waiting for their next meal to get trapped. Filled with microscopic suckers, their arms and tentacles can sometimes also lead them into sticky situations as some have been observed to get stuck in submersibles.
But these unusual creatures inhabit the ocean’s dark zone as deep as 16,000 feet (4.8 km), which makes them very elusive and extremely hard to study. In fact, there are only a few recordings of them, and most are very recent. In fact, most of what we know about them comes from videos captured by remotely operated vehicles (ROVs) to get acquainted with these “ghosts of the oceans”.
For instance, it’s not entirely clear how they feed; one theory is that they drag their arms and tentacles on the floor grabbing edible organisms, and another is that they simply use a trapping technique, waiting passively for food like zooplankton to get trapped in their sticky tentacles. Still, how exactly they use their appendages is unknown.
As a body form, having long rope-like arms could pose a problem, making the squids prone to sticking to and tangling with things — although, if you think about it, there aren’t all that many things to get tangled with down in the deep oceans. Still, the bigfin squids have another adaptation to protect them. Their appendages are bent oddly, almost as if they were dangling puppet strings. The elbow-like kinks in its arms and tentacles generally prevent it from getting the tentacles twisted with one another, allowing the creature to just drape gracefully as it wanders the waters. It also creates a very bizarre perspective, as you can see.
Because the species lives its life (or most of its life) so deep underwater, it rarely strays to the surface. It was only when remotely operated vehicles became popular and became capable of going deeper that more sightings happened.
Just recently, in 2020, magnapinna squids were recorded in the Great Australian Bight in southern Australia. This suggests that the distribution of these creatures may be more cosmopolitan than previously thought. It was the first ever sighting in Australia and researchers identified not only one but five individuals that were in close proximity to each other, something never seen before. They also had exciting behavioral observations with the squid doing a “raised arm” posture, horizontal elbow pose, and filament coiling interaction which have never been observed in any other squids. and the functional role of these behaviors in further studies.
To date, not a single specimen has been captured making species description a challenge. The closest scientists can get to these creatures for now are through video captures from ROVs. We barely know anything about them, and the same goes for plenty of creatures in the deep ocean — including many we haven’t even encountered yet.
It’s hard to know just how many of these creatures are. The ocean is so big that every time an ROV goes in, it’s a bit like a needle in the haystack — it’s hard to know if what you’re seeing is representative of the greater picture. We don’t know how many species there are, how many individuals there are, and how these individuals behave.
However, while they’re very inaccessible to humans, bigfin squids are also vulnerable to anthropogenic activities, especially with climate change altering water temperatures and food availability. Furthermore, deep-sea mining poses a threat to the known habitats of these species, especially as mineral exploration in the depths of the sea is becoming a more attractive proposition for many companies (despite the opposition of scientists and environmentalists). Though bigfin squid lives thousands of meters deep into the ocean, we should not be complacent as in one way or the other, our irresponsible decisions can impact them negatively. Otherwise, we may risk destroying them before we even get a chance to know them.
Shiella is an MS Biology student at the UNCW. In the past four years, she's been actively involved in the conservation of threatened species that receive less attention in the Philippines. She believes it is her duty to help the public understand why science and conservation are so important.