In 1973, American soldiers on the Mekong River in Laos killed and hauled ashore a massive 24-foot ribbon of a fish. It was the “Queen of the Naga,” claimed a postcard still widely circulated in Southeast Asia with the above photo, a mythical serpent thought to patrol these waters and that apparently enjoys the embrace of enlisted men.

In reality, though, the soldier had not caught a mythical beast. They weren’t even in Laos and it wasn’t even 1973. That picture with over a dozen men straining to lift the creature, one soldier so exhausted, it seems, that he had to remove his shirt and pants, was taken in 1996 near San Diego. What the men had in fact found on their early-morning jog was a stranded giant oarfish, aka “the king of the herrings,” from the Scandinavian folklore that claimed schools of the little fish dotingly followed their gargantuan leader about.

The creature’s proclivity for such strandings, and for surfacing on the open seas when sick or injured, has for thousands of years served as the likely inspiration for sea serpent legends the world over (Japanese lore says their strandings presage earthquakes and tsunamis — they don’t). Even with such history, we’re still struggling to understand this bizarre giant, which can grow to 28 feet long and, like a lizard jettisoning its tail, self-amputate up to 75 percent of its body, perhaps in anticipation of bikini season.

This could be the ocean’s most enigmatic and widely mythologized critter. One of the few people to observe a live specimen in its natural habitat, not simply stranded on a shoreline, is marine biologist Mark Benfield, who in 2013 published a paper detailing five sightings from a remotely operated underwater vehicle.

These are the first observations of healthy oarfish from an ROV. The remarkable footage, in convenient GIF format at right, captures a fish that glows almost as if lit by LEDs, thanks to a layer of guanine molecules, whose shine helps so many fish in the sea confuse and evade predators. With the oarfish, this shimmering compound will actually rub off on your hands when handling the creature, as if it’s wearing body glitter, or whatever the kids are doing to be sparkly these days.

Notice the oarfish’s famous red fins sprouting from the top of its head, which likely aid in species recognition, according to ichthyologist Tyson R. Roberts, who wrote an epic 266-page paper on the creature. (The lasers you see here and in other ROV videos, by the way, are called scalers — they allow scientists to take accurate length measurements.) The fish hovers vertically, hypnotically undulating its dorsal fin up and down, then retreats by switching to horizontal swimming, waving its whole body back and forth like an eel.

So if it can move like a typical fish, why bother going vertical? “We know that they feed on krill, the euphausiids, and if you’re looking for euphausiids and you’re in the ocean, then looking straight up will allow you to silhouette them against light from the surface,” said Benfield. “So that’s probably why they orient vertically. It also means that when a predator is looking downwards towards you, you’re presenting the minimal cross section to that animal.”

While the oarfish has typically been described as a deep-sea creature, Benfield suspects that it may not necessarily be sequestered to such a zone. While the specimen he filmed was 1,500 feet deep, that was during the day. That’s important because many sea creatures are vertical migrators — hanging out in the darkness of the depths by day, then moving toward the surface at night. Indeed, the oarfish’s favorite food, krill, embark on such endeavors, so the beast could be pursuing them.

You may notice that the fish Benfield filmed looks rather … abbreviated compared to the oarfish held by the soldiers. It’s a younger specimen, sure, but its proportions are definitely awry. And it could well be that the creature had at some point gone and popped its own tail right off.

Such self-mutilation, more formally known as autotomy, meaning “self-cutting,” is perhaps most famously demonstrated by lizards, which shed their tails when grasped. Not only does auto-amputation free the creature from its predator, but the wiggling tail left behind serves as a distraction. It’s a brilliant adaptation to escape predation and to terrify 8-year-old me, who didn’t mean to snap that lizard in half, honest.

Anyway, anatomically, the oarfish consists of a head and an abdomen, where all the guts are stored, followed by an enormous tail. At nearly 30 feet, the oarfish can have 416 dorsal fin rays, but one specimen in the Australian Museum has only 95 — coming up more than 300 short, according to Roberts. But the end of the thing is a “healed stump with the typical shape of the terminus,” making it unlikely that it was simply the victim of a shark attack.

This particular oarfish, says Roberts, had willingly amputated damn near the entirety of its body. He further writes that oarfish have few if any predators, noting that dead or dying specimens do not attract sharks and that no oarfish have been found in shark stomach contents, perhaps ruling out amputation by predator.

(Now’s as good a time as any to mention that the oarfish’s gelatinous, flabby meat is apparently pretty awful. Roberts cites an account from 1798 that claimed that not even “dogs would not eat the flesh either raw or boiled,” confirming that science in the 18th century consisted at least in part of cooking rarely seen species and feeding them to your pets. Even seagulls, which would probably eat your suntan lotion given the opportunity, are said to avoid oarfish corpses.)

So, alternatively to lizards, the oarfish, Roberts writes, could be using auto-amputation “to increase its overall fitness and survivability by ridding itself of a large part of the body that becomes increasingly useless as it grows larger. This could represent a considerable saving in energy and food resources needed to sustain the tail portion of the fish if it is not autotomized.” Such energy is better spent growing and maintaining organs.

A recent discovery of dead oarfish in California, though, calls the creature’s immunity to sharks into question. In October of 2013, a snorkeler found a 18-foot specimen, and the ensuing dissection by University of California, Santa Barbara scientists revealed larval tapeworms in the beast’s intestines. But how exactly can a parasite tell us what preys on oarfish?

This particular species of tapeworm spends its larval phase in fishes like the oarfish, then waits for its host to get eaten by a shark. Once inside the shark it’ll resume its life cycle and finally mature, so finding larval tapeworms inside an oarfish suggests they are there for a reason, namely hoping that their host isn’t all that great at not getting eaten. Thus the oarfish’s self-destructiveness may indeed be a measure to better survive shark attacks.

If it is in fact menaced by sharks on the open sea, it sure does come across as a largely carefree fish, showing not a bit of alarm at the radiant ROV getting up in its grill. So perhaps it is that this once mythical beast is indeed the badass of sailor lore, a sea serpent without a fear in the world. Except bikini season, of course.

Browse the full Absurd Creature of the Week archive here. Have an animal you want me to write about? Email matthew_simon@wired.com or ping me on Twitter at @mrMattSimon.

References:

Roberts, T. (2012) Systematics, Biology, and Distribution of the Species of the Oceanic Oarfish Genus Regalecus. Museum d Histoire Naturelle. 9782856536773

Benfield, M., Cook, S., Sharuga, S., Valentine, M. (2013) Five in situ observations of live oarfish Regalecus glesne (Regalecidae) by remotely operated vehicles in the oceanic waters of the northern Gulf of Mexico. Journal of Fish Biology. doi:10.1111/jfb.12144