The ocean shelters in its depths, mysterious animals. Among them a creature that one essentially does not know, than by corpses. The sea serpent. These strandings allowed scientists to study the strange anatomy, of this bony fish, the longest in the world.
His head crowned with a ray forelock, earned him the name king of herrings, or more commonly Regalec. But for lack of having been able to observe him alive, almost nothing was known about its biology. Till today. off our shores, a world first. A unique scientific experiment, will accidentally allow to experienced divers, to observe, study, and reveal extraordinary manners, of this unique creature.
Until the beginning of the 19th century, the sea serpent belonged to sea monsters. legendary creatures that haunted the imagination of men, and shaded areas of nautical charts. Its astonishing appearance, its size, its rarity and its colors, aroused among sailors and fishermen, stories, superstitions. We would have seen him attacking the ship, they even deck it out with fearsome teeth, who made him look like to a marine reptile. In the 19th century, his teeth went gradually disappear, thanks to the descriptions of the first naturalists.
They definitely classified it, among the fish. Nevertheless, their sightings are rare, unpredictable and scattered. For two centuries, we have identified less than 250 Regalec strandings, dying, dead or atrophied, on temperate coasts of the whole world. The longest ever recorded, was eleven meters long. Recently, by an incredible combination of circumstances, this giant fish would have was observed alive, in the Mediterranean Sea. In the south of France, the carefree Côte d'Azur.
Its Yachts, its citadels, and these fine sandy beaches. More than 12 million swimmers taste each year, to the pleasure of warm waters of its thin coastal fringe. But who could believe, that setting up a strange scientific device, off its beaches, bring back sea monsters? However, this is the consequence indirect from an unusual experience. In the heart of the summer of 2000, the oceanographic observatory of Villefranche-sur-Mer, in collaboration with the biggest international space research organizations, undertakes to deploy, 60 km off the coast of Nice, an oceanographic buoy called the Compass. Its purpose seems more poetic than scientific. It is intended to acquire data in situ of the color of the water, and pass them on.
These data will make it possible to calibrate satellites that observe the oceans. The color of the water, which varies according to the seasons and the places, is a good indicator the presence of plankton. So, in the spring, microscopic algae and their predators abound. We are talking about planktonic blooms. Algae chlorophyll gives a green color to sea water.
Here begins the vast chain ocean food. To know the evolution of the Mediterranean, buoy observations and compass, must be continuous, over several years. At the heart of this technical device, a passionate biologist. I am David Luquet. I am a scientific diver. I work at the Observatory of Villefranche-sur-Mer, and I am responsible for the maintenance compass buoy. Also with tools rudimentary than effective, it only intervenes in the first meters, on the submerged structure of the buoy.
Beyond that, he passes the baton to others underwater work specialists. To be at the heart of production plankton, the scientists decided to dock the buoy in the middle of a rotating current, called the Liguro-Provençal current. Issue, at this point, the depth reaches 2500 meters. A heavy wetting overcome 2.5 km of Kevlar cable, must therefore be filed. Lost in the vastness of the ocean, the buoy, its structure and its chain, serve as a point of reference for passengers, of the Liguro-Provençal current.
The roofs of wrecks. The amberjacks. Pilot fish. And finally the cerniers. These fish live in the photic zone, shallow water layers, sufficiently exposed to light for photosynthesis to be possible.
Tropism of the buoy shadow cone, they find there both lodging and cutlery. Most navigate by sight. Some come to feed on the algae that grow on the structure, and the little ones are devoured by the older ones. Others, finally, like pilot fish, have specialized in a particular activity. Collecting meal crumbs, or parasites of large predators, who visit the buoy. Including, the most dreaded.
The great white shark. The shark was observed only in the spring near the surface. Describing wide circles concentric, around the compass. A small estimated population at only 350 White Sharks, survives in the Mediterranean. What are they looking for here? 60 km from the beaches? Certainly others buoy visitors, like tunas. But it has never been seen feeding there.
And his stays are rare and brief. Every month, David expects to unexpected encounters, when he comes to maintain the buoy. Its mission: to clean sensors underwater optics. The material is always so basic but effective. Securely attached to the diver for not to fall 2500 meters lower.
Risky dives. David is alone, above the big blue, without protection. In less than a month, algae colonization and molluscs, render completely ineffective the 20 buoy measuring instruments. Each sensor has its own brush. Cleaning creates vibrations, sounds, emitted in all directions.
Waves that are perceived by animals that gravitate near the buoy. They arouse their curiosity. Off these sounds spread along the chain to the depths.
The fish do not know the man, so they don't fear him. Their curiosity is mutual. David under the buoy, it is the man facing the unknown. One day in April during the planktonic bloom, the water was really very cloudy. I had just finished my work, and I went down to inspect the bottom of the buoy at the level of the Kevlar cable. And there...
I saw a very long silver ribbon rising from the depths. The King of Herrings. The visiting Dark Ambassador, at the edge of our world. For the first time in the world, a diver swims with the mythical fish.
David discovers that he swims vertically and not horizontally, like sea serpents old engravings. Strange, the tail of the animal is severed. Is it due to a meeting with the white shark? To answer this, we must be able to observe the bite marks closely. Unfortunately, the bubbles of David seem to frighten the animal.
This accidental encounter is too brief to examine the wound. After a few minutes, the crowned fish, returns to the aphotic zone, those depths where penetrate so little light, than photosynthesis is no longer possible. To anticipate other meetings, you must already understand how the treat, manages to detect the buoy in the dark, and the immensity of the current Liguro-Provençal. Luckily for David, thousands of km from the buoy, a series of extraordinary events was going to allow scientists, to reveal unknown facets of the biology of the mythical fish. In Japan, regalec is known as the strange name of Ryugu no Tsukai. Understand, the messenger of the Palace of the Gods.
In a few months of winter 2014, more than a dozen treats of all sizes, have been filed by sea currents, on the shores of southern Japan. According to Japanese mythology, the messengers from the Palace of the Gods, would announce by their strandings, an impending earthquake. These impromptu appearances, could never be correlated with the seismic activity of the region.
But offered Doctor Tyson Roberts, the world specialist in Regalec, an unexpected opportunity, to conduct a systematic study on fresh animals. This is a treat. It measures eight meters. It's the longest fish bones of the world, with maybe the smallest brain of the world relative to its size. To prove it, he will use the latest in technology, in a veterinary clinic. The Japanese provided him with a magnetic resonance imaging device, or MRI which makes it possible to obtain images, in two or three dimensions of a living body.
Applied to a regalec head, MRI veterinary designed for small animals, allows you to make more images fine than with a human MRI. Essential for isolating the brain regalec and its ramifications. I would like to learn more about his brain and his endocrine system, that is to say, as in humans, all the glands, that secrete hormones in the circulatory system. For the first time in the world, we will attempt a description, exhaustive of the anatomy of the regalec. MRI images confirm the initial hypothesis. This brain does not measure about two cm, i.e. half the size of his eye.
A pea in the head. This is the size of a regalec's brain. Paradoxically, he controls the longest spinal cord, and the longest digestive tract known in a fish. Better, x-rays from a scanner from the veterinarian, will allow to enter in details, bony structures of the Regalec skull, and solve a tenacious puzzle. How is the regalec identified in the dark of the abyss? Most fish sometimes use the sight, a little the sounds, but above all the smells. But at the Regalec, this meaning seemed absent.
I looked at something like 35 specimens of regalec, and I have never seen nostrils, i.e. the ending of the olfactory system. Nobody ever mentioned the existence of nostrils, or olfactory organs at Regalec. But with this great specimen, I found the nostrils. They are neither outside nor on the side of the head. They are at the tip of his snout in the oral cavity, and can open on their anterior parts. Its nostrils are located inside its mouth.
Also to detect odors in the shadow, Regalec must keep his jaws parted, and pump water constantly. In fact, it is likely that these two olfactory organs, those little conical slits, can close. So much so that by opening them and closing them, the animal gets an indication on the origin of odors. The consequence is surprising. The regalec is able to go up the track smells in the vastness of the ocean, simply by performing pirouettes. If you smell a scent, but you don't know where it comes from, you are facing a given direction.
If this effluvium is light, you close your nostrils, and you face another direction. You then open your nostrils and you turn your head. If the smell is stronger, you are on the good road. You go up like this the trail of odors, by opening and closing your nostrils.
It's a real part underwater game. When his eyes don't see than an infinite blue, the regalec and his little brain can locate, join, and stay around the compass, thanks to an effluvium. Could it be the smell of the buoy? That of a food source? Or any other scent, emitted by a creature of the deep? To get to the bottom of it, you have to be able to dive to the edge of the photic zone. where the light stops. David Luquet, calls on a specialist deep dives in the Mediterranean Sea, Italian cameraman Roberto Rinaldi. I really want to meet the regalec.
but as soon as we left, I started to feel a bit lost in the immensity of the sea. We're gonna be little dots tiny in blue, and it's gonna be really hard to meet this fish. To flush him out and approach him, he plans to use a breathing apparatus, which combines performance and discretion. The recycler.
Today, thanks to the recycler, we can dive deep and long. We will recover the mixture gas we breathe. When we film, we do no bubbles with the rebreather. The fish are accustomed anything but bubbles. With the rebreather, we have a lot more time and luck, to approach the treats.
On the way to the compass, David suggests diving under another nearby buoy, also submerged at 2500 meters deep. A weather buoy simply called "Côte d'Azur". A sophisticated tool for measuring swell and wind temperatures, to supply data forecast centers. Under her metallic skirts, this moaning building, seems to attract fish more wide as the compass. It's creaking doors several hundred meters away, in all directions.
Nothing is left to chance. No more brief dives monthly compass. From now on, David and Roberto stay several days in a row, near the weather buoy while diving at any time.
Starting with dawn. They synchronized their coming with the peak plankton production spring, so animal protein. Thus, if the regalec is well attracted by a fragrant food source, or by the sounds of the buoy, they increase their chances of meeting. On the surface of the Vellèles. They are not jellyfish, but colonies of polyps, which drift according to winds and currents. For his first dive, Roberto immerses himself, not with a camera, but with a cane topped with a scouring sponge.
It is intended to collect mucus on the regalec's skin. in order to perform genetic analyses. David in the first meters with his bottle of air, Roberto deep in rebreather. This is how the quest is organized method of the silver snake. These serpent-like creatures, are not treats, nor jellyfish, but salps.
Filter-feeding animals bacteria and phytoplankton, who develop their chain of similar by hermaphrodite reproduction. By less than 40 meters, at the limit of hot and cold waters, where their food abounds, they clone themselves and swarm. It's in this organic soup, that Roberto met, of all records. A five-meter giant. The greatest treat never observed alive, in its environment. The longest fish bone never recorded, in the Mediterranean Sea.
Its tail is not cut, like that of the animal observed by David. An unexpected chance to seize to know him, before he leaves. To be able to take a sample of mucus, Roberto and his rebreather, will have to rely on their discretion. And wager on the curiosity of the fish.
Curiosity of fish for man, and for the buoy. Surprisingly, smooth skin and without scales of regalec, seems insensitive to this rough contact. Any contact.
But when his curiosity is sated, the giant goes back into the depths. Soaked in its precious mucus, the scraper is sent in alcohol for analysis, at the University of Western Brittany. Eléonore Méheut tries to extract the giant's DNA, and compare it to the rare samples from stranded animals. In fact, there is very little data genetics that are available, in the litterature regarding this species.
Clearly, we have a lot of things to learn from a genetic study, which would be based on specimens taken from their natural environment. After a lot of bets technically, we were able to extract DNA from the samples of mucus that we analyzed. We found 10% variations, between different individuals of the same species. It is extremely strong for the DNA sequence being determined.
It seems there would be 2 groups of treats, and it turns out that our sample is close to one of the 2 groups. These data seem consistent to the tests of Dr. Tyson Roberts, who maintains that there is not one but two species of regalec. In Mediterranean, the regalec would belong to the species Regalecus glesne. Present in the waters temperate around the world.
In warm waters of the Pacific Ocean, it is the species Regalecus russelii who would dominate. The morphological differences between the two King of herrings, are subtle. On his crown, glesne has between 4 and 7 more ridges, that russelii. The Breton laboratory is interested less to these morphological debates, only to a more pressing question. What does the regalec feed on? in the Mediterranean Sea? We left on lipid studies, not being able to study the contents of a predator's stomach, we strive to study what we called reserve lipids, which carry within them the trace of prey lipids. Unfortunately, studies that have been performed on the mucus, did not give us really satisfying results.
what we need, is to work on real regalec fabrics. A mission that seems impossible. Take pieces of fins not on one, but on several living treats.
Another difficulty, Even at the peak of the planktonic bloom, encounters remain random. Weather permitting, divers do several dives a day, on one or other of the buoys in different seasons. David's statistics are eloquent. On more than 120 compass dives, he has only seen a regalec twice.
Luck does not exist. Meetings are getting ready provoke each other, and desire each other. A treat replied at the call of the buoy, and he is not alone. In the vastness of the ocean, how can these offshore fish meet here at the same time? Probably thanks to their sense of smell.
They still have to emit a substance who travels long distances, with the currents. But what would this substance be? A pheromone, i.e. a product chemical produced by a regalec, to attract another treat.
Thus the regalec is able to send a coded message, only detectable by other treats, over very long distances. And when they are close, the treats would communicate through body language. What is his crest for? and its large pelvic fins? Obviously they look like to a signaling device, specific to the regalec. The divers go confirm his hypothesis. To be seen by his fellows, mirror-skinned fish, adopts an astonishing posture, The cross. These static postures, should allow David to approach him to take tissues.
Still need to be able swim at your own pace. And compel him to stay near the surface. Not that easy. And with its little vibrating fin, it does not move, it vibrates constantly. He is able to go very fast.
We could call it trap fish because that in fact, he has a mean attitude. but it does nothing he does not make any movements. And is it for a fish, verticality, it represents something, like for us? For divers, going down is easy, but they risk accidents decompression by ascending too quickly. One solution remains.
Go below the regalec. Over the months, David and Roberto, multiply the dives and fin harvesting. On each return to port, they send the samples at the Brest laboratory. However, like the first treat met by David, most have a truncated body. The white shark is naturally among the list of suspects.
This time, the divers had the opportunity to observe in detail multiple scars. Doctor Tyson Roberts emits a completely different assumption. Thanks in particular to the multiple stranded animals in Japan. Regalecs frequently perform a series of autotomy. What does it mean ? It means that treats amputate themselves. It's like a lizard when he cut his tail, except that a lizard only cuts its tail in one place, the regalec, he can cut the game posterior to the anus repeatedly, starting with the caudal fin, and gradually cut additional pieces, long, short, of all sizes.
And he can do this all at once up to the anus which is here. And we can find treats where that's all that's left. Unlike the lizard, the regalec would not give up its tail to escape a predator, but for other amazing reasons. autotomy, the severity of the autotomy, the number of times it is performed really depends from individual to individual.
It's a matter of saving energy. The regalec decides this metamorphosis towards a body where it does not preserve, than its gonads and vital organs. But it is very rare in fish. To date, it is the only known fish that practice this. To be able to prove this revolutionary hypothesis, should be observed this voluntary mutilation, or find body parts of regal at the bottom of the oceans, might as well look for edges in the mud of the abyss. But near the village of Macerata, on the east coast of Italy, luck smiled on a geologist.
In an abandoned quarry, Professor Patrizio Bonzi, just excavated a curious fossil deposited at the bottom of the Adriatic Sea, about 2 million years ago, then reassembled by landslide. This is the only known copy. to the world of fossil treats. This is the part posterior of the body. She is folded in on herself, but we can open it. The principle of autotomy, has therefore been engraved in ancient marine sediments, for eternity. Other clues, including their eating behavior, could be brought by lipid studies, thanks to collected fins by David and Roberto.
Still need to identify now the prey of the regalec, and therefore their lipid signature. There we will set two traps, one that will be on the surface for catch fish larvae and another a little deeper to catch small crustaceans, like copepods. Like an underwater lighthouse, the light from the trap arouses curiosity of the little people of darkness. Some gravitate around the net.
Others come to find refuge there. By day, the peaches are lean. But when the trap is submerged overnight, morning collections hold many surprises. These little shrimps are not other than krill.
This species, present in abundance in the North Atlantic, would shine these bioluminescent organs, in the aphotic zone of the Mediterranean. Better, after analysis of the samples at the University of Western Brittany, the lipid signature of this krill, is found in the flesh of the regalec. But at night, krill perform vertical migrations, to approach the surface and feed on plankton.
Thus, it avoids daytime hunters, like most fish which revolve around the buoys. But in its wake, it drives all these predators. Whose sight is suitable at very low light. Among them, the regalecs. In an attempt to observe their feast, aquanauts must dare night dives.
Offshore, in a rebreather, without any mark, and above 2500 meters of weightlessness. You really have to be careful. We are in complete darkness. And we don't have possibility of orientation. Strange Gelatinous Visitors are appearing, in endless darkness.
Like a super organism, these aliens from the depths are coming up together every night. For an extraordinary feast. It's the biggest migration of biomass in the world. In their stinging trap, krill, a promising sign.
But where have the fish gone? Residents of the day? They seem to fear great invisible predators. And regroup. Same with phantom threats, David and Roberto get closer. To better monitor in all directions. A moon fish.
False alarm. Diving at night offshore is like a child walking into a toy store, with the beams of light, we go reveal beautiful colors, we do not see the light of day. We know that there are lots of toys everywhere. We see very little, but it's enough to be amazed by what you see. The king fish.
In his clothes of light. Only the underwater lights, reveal its exuberant colors and her mirror skin. What use are they to him? in absolute darkness? To reflect the krill lights to better interfere with its prey. Mystery. A riddle all the more insoluble, that the fish ignore the krill.
Yet he relaxes his mouth, like to catch invisible prey. The lights would disturb so his feast? On closer inspection, tiny visitors seem to come and go, at will in the mouth of the regalec. Parasites.
These are external parasites, who do not stay permanently in the body of Regalec. internal parasites, allow you to place the regalec in the food chain, in particular, to know its predators. At least that's the opinion American doctoral students, specializing in the study fish parasites. At the University of Santa Barbara in California, these are stomach contents failed treats that allowed, to Sarah Weinstein and Anna Garcia, to make amazing discoveries.
Parasites provide a beautiful overview of the life of the regalec, information that we do not could not have otherwise, because these parasites have cycles growing complex, across multiple hosts. For example, we found at least three species of nematodes. That's really interesting. 'Cause one of them looks like much to a species that uses, marine mammals as their last guest. After in-depth analysis, the University of Santa Barbara confirmed that the presence of juvenile nematodes, in the viscera of Regalec, would prove that this fish, is prey to predators depths.
Like sperm whales. Indeed, these large cetaceans are known, to be the hosts of the same species of nematodes, at the adult stage. nematodes that live in the flesh of the regalec, arrives with the prey which it consumes like krill. But the krill would also bring it these bioluminescent bacteria.
But to date, no bioluminescent organ was found on the regalec. They are indeed difficult detectable in dead fish. The lights emitted by most bioluminescent fish, are so weak that we cannot detect them with the naked eye. This is the case with Regalec. Also, David and Roberto suggest to replace ordinary lamps, by ultraviolet lamps. Abbreviated uv, which reveals the fluorescence of living things.
In particular the luminous lures krill eaters. By identifying fluorescent areas, organs are isolated including bioluminescence, could be revealed by an analysis chemical and microscopic. Unfortunately, the scope of these UV lamps in the water, is much less than that ordinary lamps, which nullify their effect. Exercise is both dangerous and difficult. David will have to spot the treat with white lights, then turn them off and leave Roberto and his uv, approach it very closely.
Dared bet. Bet won! UV lamps reveal 2 organs fluorescent on the regalec's skull, one under the chin, the other on the forehead. These organs could be bioluminescent, but only a thorough examination on live or dying fish, could confirm it. Like miniature light traps, they would allow treats, to lure its prey.
Its beauty can also be fatal, for divers. At some point I realized that its crest rose upwards. And I realized that we were descending at top speed. When I looked at the watch, we were at 71 meters. It is a trap of this small fish. He brought me to his home, to his abyss. The sea serpent is not plus the mythical creature, which devoured the ships.
Only her bewitching beauty can be fatal. It's up to the diver to conceal it, to say it better the king fish world. A rare animal. Harmless.
And magical.
2023-03-07