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Mystery Monsters of the Deep Dark Sea

We live on a planet mostly plunged into cold darkness. Most people know that two-thirds of the Earth’s surface is covered with water, but have you ever stopped to think about how most of that area lies in the deep dark where no sunlight ever penetrates? The fact is that the majority of our planet lies in a cold, eternal night; a practically unexplored alien world deep under the sea that lies in perpetual darkness.

The sunlit zone of the world’s oceans, where 90 percent of all known ocean life resides, extends only to around 600 feet down, sunlight slowly fading in ever darkening bands as the depth increases. The rest lies within what is known as the twilight, or disphotic zone, and then deeper into the midnight zone, known as the aphotic zone. Of all of our vast oceans which cover most of our planet, 90 percent of these waters lie deep within the stygian chasms of perfect pitch blackness within the midnight zone. It is a cold place, perpetually blanketed with darkness and immense, crushing pressure, where nightmarish creatures skitter and flit far from the sunlit world with which we are familiar. Very little is known about this dark world. Such depths are notoriously difficult to study and we have only barely scratched the surface of what lies there.


All we know for sure is that the truly deep depths of the world’s oceans offer continual surprises. New species unlike any others known before are routinely discovered here, and indeed wholly new and alien biomes in extreme environments that no life had even been thought possible, such as deep sea thermal vent communities, have challenged our very notions of what life is and how it has evolved. These depths and the bizarre organisms that call them home are so alien that they are often used as a template for what we might expect to find in extreme habitats on other worlds.

As inhospitable as the deepest, coldest abyssal depths of the ocean may seem, this is a place in fact teeming with life, far from the desolate undersea desert it was once thought to be. Craig M. Young of the Oregon Institute of Marine Biology once described the abyss as having biodiversity that “may exceed that of the Amazon Rain Forest and the Great Barrier Reef combined.” It is little wonder then that from these dizzying, midnight depths spring unexplainable mysteries and undiscovered organisms that we still do not grasp. Let us delve down, down, down into the inky murk of this dark earth and take a look at some of the perplexing enigmas that call to us from there.

Beebe’s Abyssal Fish

Some of the greatest ichthyological mysteries of the century were uncovered in the 1930s by the deep sea scientist William Beebe, who was head of the tropical research department at the New York Zoological Society. Descending in his bathysphere- a small metal spherical craft barely large enough to hold a full grown man- into the deep dark sea off of the coast of Bermuda, Beebe was the first person to brave such crushing depths and truly get a look at the alien world that lies in the eternal night of our world’s deep oceans. What he saw was a place unlike any that had been ever observed before; a vast sea of pitch black inhabited by translucent, gelatinous creatures, glowing jellyfish, fanged monsters, and the innumerable twinkling lights of bioluminescent organisms like a sea of stars in the dark cold of space. In his book Half Mile Down, Beebe wrote:

“It was stranger than any imagination could have conceived. I would focus on some one creature and just as its outlines began to be distinct on my retina, some brilliant, animated comet or constellation would rush across the small arc of my submarine heaven and every sense would be distracted, and my eyes would involuntarily shift to this new wonder.”

During his study of the Bermudan depths, Beebe made many detailed notes and sketches of his discoveries, but sadly the technology of the time did not allow for underwater photography at the depths he was operating at. Many of the creatures Beebe described and catalogued in his study, collectively referred to as Beebe’s Abyssal Fish, are still solely known from his accounts and sketches, with no flesh and blood specimen ever recovered as of yet and never seen since. Of the various unknown species Beebe observed, some of them truly stand out.


Bathysphere exploring the deep.

The fish Beebe called Bathysphaera intacta was observed at a depth of 2,100 feet in 1932, and was described as 6 feet long with a row of pale blue lights along its sides. The fish also had two ventrical tentacles trailing from its sides that were each tipped with red and blue lights, and large prominent teeth that the researcher described as being reminiscent of a barracuda’s. Beebe classified this fish with scaleless black dragonfishes of the subfamily Melanostomiidae, but the largest known dragonfish of the time was a mere 15 inches in length.

Another fish Beebe encountered was what he called the Pallid Sailfin (Bathyembryx istiophasma), a two foot long fish spied at a depth of between 1,500 and 2,500 feet. The Sailfin was of a pale, olive drab color with no discernible luminous organs and possessing a prominent long, wide, filamentous pectoral 
fin. It was seen only once, and Beebe was not able to capture the specimen.

Other smaller, yet no less mysterious fish were observed by Beebe as well. The Abyssal Rainbow Gar was a 4 inch long species observed at a depth of 2,500 feet. Beebe saw four specimens swimming in a stiff, upright posture and described them as having long beaks and colorful bodies of scarlet, blue, and yellow. There was also the bizarre Five Lined Constellation Fish (Bathysidus pentagrammus), with its round body, disproportionately large eyes, and lines of purples and yellow bioluminescent lights along its sides. It was sighted at a depth of 1,900 feet and was so unusual looking that it was speculated that Beebe had in fact seen merely a cluster of jellyfish obfuscated by mist on the bathysphere’s porthole.


Depiction of Beebe’s Bathysphere Fish

It is impossible to classify any of these fish with confidence as none of these species have ever been captured or sighted again, and they are only known from Beebe’s descriptions. In modern times, the technology to allow us to more efficiently explore these depths has progressed, so perhaps sometime in the future we may have some answers as to what Beebe saw through his porthole down there in the deep dark sea all of those years ago.

The Bloop

In the summer of 1997, the U.S. National Oceanic and Atmospheric Administration (NOAA) detected an unusual undersea sound on autonomous hydrophone listening stations situated deep in the Pacific ocean for the purpose of monitoring deep sea phenomena. The sound was an ultralow frequency and extremely loud, as it was picked up on several stations that were located up to 5,000 km apart. The bizarre sound rose steadily for over one minute, and did not exhibit characteristics inherit to man made noises such as those of submarines or drilling, nor of known geological phenomena like earthquakes or volcanic activity. The audio signature of the noise had a unique soundprint that puzzled scientists and became to be known simply as the “Bloop.”

The Bloop demonstrated some unique qualities, such as rapid variations in frequency and a rather organic sound, that fueled speculation that it had been made by some form of marine creature. The problem was that the sheer volume of the noise, which had carried it to far flung hydrophone arrays thousands of miles apart, meant that if it had indeed come from a biological organism it would be something far larger and louder than any known to currently exist. If this was some marine creature, then what sort of beast would be capable of such a massive roar?


The discovery of the Bloop became hotly debated and highly speculated upon. Theories ranged from some gargantuan unknown leviathan to a new type of whale evolved to produce sounds more efficiently and loudly. Other, more far out hypotheses believed the sounds to be from Lovecraft’s Cthulu itself, an idea encouraged by the fact that the Bloop was emitted from a point 1,760km from the location of the sunken city of R’yleh, where according to Lovecraft Cthulhu was imprisoned.

Trying to find some rational explanation for the strange sounds, some scientists pointed to data from undersea acoustic surveys conducted from 2005 to 2010 that seemed to suggest that the Bloop was most likely caused by one of the tens of thousands of icequakes that occur every year in the southern Pacific. Icequakes are caused by the melting, cracking, and shearing of sea ice as well as pieces of glaciers breaking off. Proponents of the icequake theory pointed to the similarities between the acoustic signatures of icequakes and what was seen in the Bloop, as well as the fact that icequake noise can travel thousands of kilometers just as seen in the mystery recording. It was also pointed out that the audio recording for the Bloop responsible for popularizing the theory of a large animal had been played back at a higher speed, giving it the illusion of having more of a biological quality than it possessed when played at normal speed.


The official statement that the Bloop was caused by an icequake seemed to spell the end of speculation and the whole mystery was proclaimed “solved,” yet there are still those that don’t buy into the official explanation. Skeptics of this explanation point out that it has never been shown that the signature is definitely that of an icequake, and the closest that could be said was that it was “probably” an icequake. The sound signature of the Bloop does not completely match that of an icequake, and still displays some anomalies that don’t totally fit with one. In addition, upon further analysis at least one NOAA scientist has redacted his opinion that the Bloop was caused by ice activity and has continued to stand behind the marine animal hypothesis.

It seems that this mysterious sound from the deep has perhaps not been completely solved just yet. Questions still remain. Unfortunately for those who want a concrete answer, since the Bloop was only ever heard once, we will probably never know for sure.

Super Eels

A curious finding was dredged up from abyssal depths off of South Africa in 1930. The Marine Investigation Expedition was an extensive round the world research expedition led by a Professor Johannes Schmidt aboard the vessel Dana. During the last year of the expedition, the ship fished up a colossal eel larvae, or leptocephalus, in water over a thousand feet deep off the Cape of Good Hope. Due to the extreme depths, the animal was dead upon reaching the ship, but nevertheless shocked all those who examined it.

The larvae was measured as being 184cm long (just over 6 feet), which is large but all the more so when considering that the larvae of a common eel typically measures only 2 to 4 inches, which in turn grows into an eel around 4 feet long. When extrapolating from the typical growth rate of eels, the 6 foot leptocephalus was theorized to become an adult that would measure around 80 to 100 feet in length, although a more conservative estimate would be more like 70 to 80 feet. In the freshwater eels of North America and Europe, adults can be a dozen times the size of their larval forms. According to an article in The Evening Post, Volume CXVII, Issue 47, 24 February 1934, Page 24, the South Africa specimen was subsequently preserved and sent to Marine Biological Laboratory in Copenhagen, Denmark where it was put on exhibit.


A similar find was made in New Zealand when another large leptocephalus, this time around 3 feet long, was pulled up out of the depths in 1959. In this case the larva was assigned the name Leptocephalus giganteus, and the South African specimen was later also classified under the same name even though it was not clear whether the two were actually of the same species.

Since no other specimens of Leptocephalus giganteus have been collected, there is little data to go on. However, judging from known growth rates of similar creatures, it would appear that the deep seas could be home to some truly monstrous eels indeed. These giant eel larvae fit neatly into the theory postulated by the cryptozoologist Bernard Heuvelmans of giant eels of this sort, what he referred to as “super eels,” accounting for many reported sea serpent sightings. Speaking of Heuvelmans…

Heuvelman’s Super Squid

We know the seas have big squid. The once legendary Kraken, now known as the giant squid, of the genus Architeuthis, and the even more massive colossal squid (Mesonychoteuthis hamiltoni) are famous for their enormous sizes. Giant squid, for instance, are estimated to reach total lengths (including tentacles) of up to 13 meters (43 feet) and perhaps even larger, with colossal squid being even more massive. However, is there an even more monstrously huge type of squid lurking in the unexplored depths of our oceans?

The famed cryptozoologist Bernard Heuvelmans, often referred to as the  father of modern cryptozoology, certainly thought so. Inspired by reports from outsized specimens of giant squid washed up in Newfoundland, some of the more outrageous reports mentioning squid 80 or 90 feet long, Heuvelmans wondered if there were specimens of giant squid out there, or even a new species that were far larger than the proposed size limits. Another report from 1924 further added fuel to his theory. On October 25, 1924, a Mr. White and Mr. Strachan found what they described as a “record octopus” washed up on near Baven-on-Sea, Natal, South Africa. Pieces of the carcass had been missing, including the mantle and long portions of the tentacles, making size estimations difficult, but judging by illustrations of the animal Heuvelmans estimated that the total length of the animal would have been a monstrous 115 feet long.


A fair amount of sightings reports also fascinated Heuvelmans. One such sighting occurred at night during WWII by an A. G. Starkey off the Maldives. He was allegedly alone on deck and saw a squid laying alongside the 175 foot (53 m) boat that was nearly the same length. He said the arms were 2 feet wide (0.6 m) and that the beak was visible. A canadian by the name of Charles Dudoward also reported spotting a squid washed up on shore in 1922 that had arms 50 feet (15.2 m) long and one tentacle 100 feet (30 m) long. The tentacle apparently ended in a hook 10″ (25 cm) wide and 12 in (31 cm) long. Dudoward’s own grandfather had also made a sighting in British Columbia of a squid which had arms over 100 feet (30 m) with suckers ranging from the size of saucers to basin plates.

Heuvelmen’s also considered as evidence of giant squid the existence of sucker marks on sperm whales far larger than normal which he took to imply truly humongous squid lurking in the depths. Upon hearing of sucker marks 4 inches in diameter, Heuvelman’s extrapolated that into a squid with a body length (excluding tentacles) measuring at least 30 feet long. Even larger sucker marks had also been recorded, with the famed cryptozoologist Ivan Sanderson writing of sucker marks measuring 18 inches long. Sanderson had also made mention of sucker marks measuring all the way up to 2 feet in diameter, all of which would imply gigantic squid far, far larger than any known thus far. It was pointed out by skeptics that these extra large sucker marks may have been marks made by lampreys rather than those of squid, or that they could have been wounds inflicted on young whales that grew to appear larger as the animals matured, but Heuvelmans was not convinced by these arguments. Heuvelmans also took reports of tentacles measuring 45 feet long and speculated that they were short arms rather than the long tentacles, from which he calculated that the creature itself would reach the truly mind boggling total length of 140 to 240 feet if male and up to 300 feet if female.

Artwork by Chris Garrett at Deviantart

Artwork by Chris Garrett at Deviantart

Based on all of these observations, plus various sightings reports of super sized squid from around the world, Heuvelmans proposed that there were squid that measured well over 100 feet and in some case up to 300 feet lurking in the world’s oceans. This seems perhaps a little far fetched, yet even if they are not hundreds of feet long it is entirely feasible that squid at least larger than any currently known are out there prowling the depths.

Mystery Shark of the Mariana Trench

It is impossible to talk about the truly deep places of the world without mentioning the Mariana Trench, a massive undersea canyon stretching around 2,550 km (1,580 mi) along the western Pacific Ocean. Dropping down up to 7 miles into darkness at its deepest point, the yawning chasm of the Mariana Trench is the deepest part of the world’s oceans, and remains mostly unexplored.

Along the outer edge of the Mariana Trench lies the extremely deep Suruga Bay, Japan. It was here that researchers caught footage of a truly monstrous shark while studying the marine life of the area. Japanese marine biologists studying sea life at the bottom of a deep and little explored part of the bay set up a container filled with potently smelly bait designed to lure in a wide variety of sea life even from great distances away. The container was placed at a depth of 1.5 km (nearly 1 mile), and a camera was attached nearby to capture footage of any sea life in the vicinity. The plan was to take video of and catalog the different types of creatures that showed up.

At first, the bait attracted numerous small fish and some crustaceans, nothing particularly unusual. Things got more exciting when a shoal of rare, deep water sharks measuring around 2 meters (6.5 feet) long moved in and enthusiastically fed on the bait. Researchers were surprised when the shoal of sharks suddenly and inexplicably darted off in all directions as if they were afraid of something. At first, it was unknown what could have caused such large sharks to scatter like that away from such irresistible bait. The reason soon became apparent when a humongous shark dwarfing the others loomed into view from the surrounding murk. The incredibly large shark proceeds to slowly soar in front of the camera and show interest in the bait before gliding off again. The scientists who viewed the mysterious shark were puzzled by its sheer size, and nobody was sure just what exactly they had seen.

Still from the video footage.

Still from the video footage.

It is apparent upon viewing the footage that whatever the shark is, it is gigantic, although it is difficult to say for certain just how gigantic. When trying to ascertain its size, researchers took into account the dimensions of the bait container, as well as the length of other sharks that can be seen in the footage before the monster shows up, which were judged to be around 2 meters (6.5 feet) long. Using these as size comparisons, the mystery shark was estimated as being at least 30 feet long, with more exaggerated estimations putting it at more like 50 or 60 feet long.

The footage taken by the underwater camera near the bait station became quite popular in Japan, and it has gained some notoriety in cryptozoological abroad as well. It is unclear just what is seen in the video, and some have jumped on the explanation that the mega shark is a surviving megalodon. The researchers who originally took the video are inclined to believe it to be a very large specimen of the rare Pacific sleeper shark, and other scientists have concurred. Sleeper sharks can get quite large, and are believed to be capable of reaching lengths of up to 7 meters (23 feet) long, yet if the shark in the video is of this species then it would represent by far the largest specimen ever recorded.

Pacific sleeper shark

Pacific sleeper shark

Arthur C. Clarke once said “How inappropriate to call this planet Earth, when it is quite clearly Ocean.” How true this is. Our world is mostly comprised of vast, largely unexplored water plunging into an even vaster, even more unexplored perpetual twilight. Just what lies hidden down in this darkness that makes up most of our planet? We have scarcely managed to uncover even a fraction of the myriad organisms that call these abyssal places home. There in this zone of black and amidst the flickering constellations of bioluminescent lights lie ancient mysteries that remain and perhaps always will.


Brent Swancer is an author and crypto expert living in Japan. Biology, nature, and cryptozoology still remain Brent Swancer’s first intellectual loves. He's written articles for MU and Daily Grail and has been a guest on Coast to Coast AM and Binnal of America.
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