Deep Sea Gigantism: Curious Cases of Mystery Giant Eels

Among the vast and varied catalog of odd aliments out there, gigantism is a rare condition that refers to abnormal growth among members of a species, primarily due to imbalances in the regulation of growth hormones. Famous instances of this among humans would include giants like Robert Wadlow, who stood at a height nearing nine feet during his lifetime, remaining a record according to Guinness World Records.

But gigantism can occur among other species just as well. One particular area where the effects of an environment can seem to lend itself to species of larger size is within the deepest areas of the ocean. Hence, a term unto itself, deep-sea gigantism, was coined to deal with the prevalence of enormous squids, crabs, tube worms, and other colossal critters that emerge from the deepest ocean depths. Much as was the case with early reports of krakens and other sea monsters, later found to represent real species such as the giant squid, there my yet be giants out there swimming around that we remain presently unaware of. In fact, there is a multitude of evidence suggesting that enormous eel-like creatures may inhabit the deep ocean depths.
One of my favorite stories dealing with the matter of giant eels occurred in 1930, where Danish sea scientist Anton Bruun managed to capture something strange-looking in a fishing net off the coast of South Africa. The creature had resembled a fish somewhat, but had a thin, translucent body about six feet in length. Bruun recognized the creature to be a leptocephalus, that is, the larva of some sort of eel. It isn’t uncommon for certain eels to grow to sizes larger than six feet in length; however, their larvae are proportionately much smaller, typically only one-thirtieth the size of the mature adult. If the specimen Bruun managed to capture was only the animal’s larval form, then how big would the adult have to be?

Bruun outlined this for us as well, estimating an adult of the species reaching a projected length of 180 feet, far longer than even the largest know denizen of the depths, the Blue Whale. This wasn’t the only sighting of what may have been a giant leptocephalus, however. Later in July 1963, Dr. Lionel Walford was aboard the research vessel Challenger when he described having an encounter with a large, translucent “sea snake” swimming off the coast of New York:

“It resembled a transparent sea monster. It looked so much like jelly. I could see no bones and no eyes, nose, or mouth. But there it was, undulating along, looking as if it almost made of fluid glass.”

Was this also an enormous larvae of an unknown species of eel, whose parents must have been even more tremendous in size? Of course, for evidence of sightings of the parents themselves, we must look no further than the multitude of reports of sea serpents described over the years. One historic instance of particular significance took place aboard the ship Daedalus on August 6, 1848, and arguably, the ship is best known even today for its famous encounter with a lizard-like sea serpent.

While traveling along the coast of South Africa toward St. Helena, the Daedalus’ Captain McQuhae and his shipmates reported seeing an enormous sea serpent west of the Cape of Good Hope. Approximately four feet of neck was visible, raising the creatures’ head above the water as it “passed rapidly, but so close under our lee quarter, that had it been a man of my acquaintance I should have easily have recognised his features with the naked eye.” Incidentally, a similar encounter had occurred exactly thirty-one years prior on the same date in August, when a serpent like beast was seen swimming off the southwest coast of England near Gloucester.

Could these famous serpents represent mature specimens of the sort of creatures described by Bruun and Walford in the years that followed? If so, it may well be that the strange sea serpents witnessed occasionally are, in reality, enormous eels that perhaps only rise to the surface with the sparsest frequency… or as Bruun himself supposed, in accordance with their mating habits. If this theory turned out to be accurate, the popular given name of “sea serpent” would be something of a misnomer, since the animals in question, though clearly snakelike, might in fact be more similar to fish!

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Micah Hanks is a writer, podcaster, and researcher whose interests cover a variety of subjects. His areas of focus include history, science, philosophy, current events, cultural studies, technology, unexplained phenomena, and ways the future of humankind may be influenced by science and innovation in the coming decades. In addition to writing, Micah hosts the Middle Theory and Gralien Report podcasts.
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