Smallmouth macropinna for a long time did not allow zoologists to sleep peacefully. Her transparent head and unusual cylindrical eyes remained a mystery to them. The answer was found only in 2004.
Thanks to the transparent shell on the head, the fish can observe what is happening around it. But the biggest surprise was her eyes. Looking at the image, guess where they are located?
I didn't guess at first. The holes above the mouth, which I initially mistook for eyes, actually turned out to be olfactory organs. And what is inside the transparent head and very much resembles 2 green hemispheres, actually turned out to be the eyes of a fish. They are separated from each other by a thin bone partition.
In the light, the eyes take on a bright green color. This is due to the content of a special yellow pigment in them, which filters light and reduces its brightness. I would like to remind you that many deep-sea fish have poorly developed vision. This cannot be said about the macropinna, so it should protect its eyes from the bright light that it may encounter when rising to the upper layers of water for prey.
The world learned about this fish only in 1939, when it was accidentally caught in fishing nets. Its study and primary description William Chapman took over. But due to its deep-sea habitat, it was not possible to study this fish in more detail, and you can’t get much from one sample. In addition to this, with a sharp change in pressure (from depth to surface), its transparent shell, protecting the eyes, ruptured.
And only in 2004 scientists managed to see this fish in their natural environment habitat at a depth of 500-800 meters. This became possible thanks to scientists from Research Institute Monterey Bay Aquarium and deep-sea ROVs, which were used to film video and take the first pictures of clear-headed fish.
The body of this small fish, 10 - 15 centimeters long, covered with dark scales. Despite the large throat, the mouth opening of the fish is quite narrow, which is why it has to monitor the size of its prey. Swimming horizontally, the fish's tubular eyes are always directed upward. Thus, she looks out for her prey located in the upper layers.
And after 5 years, in 2009, they managed to catch several specimens of fish and observe their behavior in a special aquarium. And here are the results the scientists came to. It turns out that the fish's tubular eyes can rotate. This happens during hunting, when the fish, having noticed prey, positions its body vertically.
Various crustaceans, siphonophore tentacles, cnidarians and other zooplankton were found in their stomachs. Swimming slowly in the water column, the fish looks up. As soon as she notices above her tasty, then swims under it and moves its body vertically to grab the prey. At this moment, her eyes move 90°, leaving the prey in her field of vision.
Moving cylindrical eyes Judging by the fact that it has to deal with the poisonous stinging tentacles of siphonophores, the integument of this fish is immune to their poison, and the eyes are reliably protected by a transparent shell.
Fish lives with transparent head in subarctic and temperate waters Pacific Ocean: Kuril Islands, northern Japan, Bering Sea, west coast of Canada and the USA, as well as in the Gulf of California area.
Well, who doesn’t know this fish on the Internet - of course everyone knows. However, I will try to collect more information and tell you about it again, and add it to our collection most interesting fish it will be very useful :-)
Smallmouth macropinna or barrel eye - the only fish in the world, having a transparent head. It was discovered and described in 1939 by scientist Chapman, but photographs of living fish were obtained only in 2004. Actually, it was then that it became known about the structural features of her head, since the previously fragile transparent dome was destroyed when the macropinna was removed from the water.
For a long time, the smallmouth macropinna did not allow zoologists to sleep peacefully. Her transparent head and unusual cylindrical eyes remained a mystery to them.
Thanks to the transparent shell on the head, the fish can observe what is happening around it. But the biggest surprise was her eyes. Looking at the image, guess where they are located?
The holes above the mouth, which you probably initially mistook for eyes, actually turned out to be olfactory organs. And what is inside the transparent head and very much resembles 2 green hemispheres, actually turned out to be the eyes of a fish. They are separated from each other by a thin bone partition.
In the light, the eyes take on a bright green color. This is due to the content of a special yellow pigment in them, which filters light and reduces its brightness. I would like to remind you that many deep-sea fish have poorly developed vision. This cannot be said about the macropinna, so it should protect its eyes from the bright light that it may encounter when rising to the upper layers of water for prey.
The bright green eyes of this small fish (it does not exceed 15 cm in length) are located in the head chamber filled with transparent liquid.
This chamber is covered by a dense, but at the same time elastic transparent shell, which is attached to the scales on the body of the smallmouth macropinna. Since the smallmouth macropinna is characterized by a special structure of the eye muscles, its cylindrical eyes can be in both a vertical position and in a horizontal position, when the fish can look directly through its transparent head.
Thus, macropinna can notice prey both when it is in front of it and when it swims above it. And as soon as the prey - usually zooplankton - is at the level of the fish’s mouth, it quickly grabs it.
Despite the fact that since the discovery of this amazing fish, much has been learned about it, it still remains poorly understood. This is largely due to the fact that smallmouth macropinna lives on very great depth. Typically, this fish is found at depths of 500 to 800 meters, however, it is believed that it can live at much greater depths.
Macropina spends most of its time motionless or moving slowly in the water. Until recently, it was believed that the peculiarity of the structure of its eyes is such that the fish cannot rotate them. However, this turned out to be only partly true. Floating horizontally, her eyes always look upward, straight through the transparent dome. Having noticed prey above itself, the macropine has to take a vertical position in the water so that its eyes turn forward. After this, she can control the process of absorbing prey, that is, she knows at what time to open her mouth.
Although smallmouth macropine is a predator; it cannot catch prey large enough for its size. This is due to the fact that it has a small mouth and few teeth. Therefore, the fish is content with small fish, crustaceans, and also the tentacles of poisonous siphonophores. It is possible that the appearance of a transparent dome covering the eyes is precisely an evolutionary adaptation for protection from poisonous tentacles of his prey.
The world learned about this fish only in 1939, when it was accidentally caught in fishing nets. William Chapman took up its study and primary description. But due to its deep-sea habitat, it was not possible to study this fish in more detail, and you can’t get much from one sample. In addition to this, with a sharp change in pressure (from depth to surface), its transparent shell, protecting the eyes, ruptured.
It was only in 2004 that scientists were able to see this fish in its natural habitat at depth. This was made possible thanks to scientists from the Monterey Bay Aquarium Research Institute and the deep-sea ROVs, with which they filmed video and took the first pictures of the clear-headed fish.
The body of this small fish, 10–15 centimeters long, is covered with dark scales. Despite the large throat, the mouth opening of the fish is quite narrow, which is why it has to monitor the size of its prey. Swimming horizontally, the fish's tubular eyes are always directed upward. Thus, she looks out for her prey located in the upper layers.
And after 5 years, in 2009, they managed to catch several specimens of fish and observe their behavior in a special aquarium. And here are the results the scientists came to. It turns out that the fish's tubular eyes can rotate. This happens during hunting, when the fish, having noticed prey, positions its body vertically.
Various crustaceans, siphonophore tentacles, cnidarians and other zooplankton were found in their stomachs. Swimming slowly in the water column, the fish looks up. As soon as she notices a tasty morsel above her, she swims under it and moves her body vertically to grab the prey. At this moment, her eyes move 90°, leaving the prey in her field of vision.
Judging by the fact that it has to deal with the poisonous stinging tentacles of siphonophores, the integument of this fish is immune to their poison, and the eyes are reliably protected by a transparent shell.
The fish with a transparent head lives in the subarctic and temperate waters of the Pacific Ocean: the Kuril Islands, northern Japan, the Bering Sea, the west coast of Canada and the USA, as well as in the Gulf of California.
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Despite the fact that the smallmouth macropinna (lat. Macropinna microstoma ) was discovered back in 1939, it was only recently possible to study it. Previously, when examining the transparent head of this deep-sea fish, scientists could not figure out how it sees prey, because its gaze must always be directed upward.
In fact, those specimens that meticulous researchers came across were severely injured when rising to the surface. Only 70 years later, in 2009, the world was able to see photographs of a living macropinna. At the same time, the structure of the eye of this unique underwater inhabitant became known.
And the visual organs of the smallmouth macropinna are cylindrical in shape, for which it was nicknamed the barrel eye. The transparent periocular bones, together with the elastic covering membrane, provide their protection. It was this shell that was lost when the unfortunate fish fell into the net and was thrown out at the stern of the ship.
The eyes themselves are located in a chamber filled with a special liquid. They are separated by a bony septum, which also houses the brain. True, for this it is slightly extended back and expanded.
At first glance at a photograph of a macropinna, it may seem that the fish has eye holes that are located directly above the mouth. These are actually the olfactory organs - large, rounded pockets containing olfactory receptor lattices. The barrel eye has a large throat and a small mouth, so it cannot catch large prey.
The fish itself is small - up to 15 cm in length. Her entire body, except her head, is covered with dark scales. The rounded fins are quite large. It is they who help the macropinna remain practically motionless, hovering in the water column. Wherein pectoral fins She holds it horizontally, and tilts her abdominal ones at an angle of 30 degrees. At the slightest danger, the barrel eye quickly presses all its fins to its body and swims away with the help of sharp beats of its tail.
These unusual fish live in the north of the Pacific Ocean, preferring its temperate and subarctic waters. They were most often found off the coast of Japan and the Kuril Islands, as well as in the Bering Sea, near the western coasts of the USA and Canada and south to the Gulf of California. Smallmouth macropinna loves depths from half a thousand to 800 meters. Moreover, the more meters from the water surface, the larger sizes the fish itself.
The barrel eye feeds on various zooplankton: small crustaceans, cnidarians, and also swallows siphonophores directly along with their cnidocytes. The fish hunts in two ways: it either waits until the prey descending down is at mouth level and grabs it, or it itself raises its head up to catch the prey swimming above its head. Her peculiar eyes, which either look up or are directed horizontally, help her a lot in this.
Scientists suggest that the macropinna acquired a transparent shell as a result of evolution as protection from cnidocyte siphonophores. Cnidocytes are a kind of stingers that siphonophores use to attack enemies and protect themselves from predators. Obviously, in the case of the barrel eye, this weapon was not very effective.
The smallmouth macropinna or barrel eye is an unusual deep-sea creature with a transparent head.
Nature constantly surprises us with unusual and amazing representatives animal fauna. Can you believe that there are fish with completely transparent body parts? The smallmouth macropinna is just such a mysterious creature, beyond understanding.
She also has one more unusual name- barrel eye. This fish is a representative of the ray-finned class, belongs to the order Smeltfish and the family Opisthoproctaceae. On this moment The barrel eye is the only deep-sea creature known to science, which is assigned to the genus Macropinn.
This strange inhabitant The seabed was discovered back in 1939. But the level of development of science and the equipment available to scientists did not allow them to get closer meet macropinna and study it. This transparent creature was remembered only seventy years later, when New Zealand fisherman Stuart Fraser caught a barrel eye in sea waters seventy kilometers from the Karikari Peninsula.
He decided that a crumpled plastic bag thrown out by someone was floating on the water surface. But taking a closer look, has concluded, What is this Living being. As Stewart himself admitted, the unusual find amazed him, and after catching transparent fish, at first he was afraid to take it in his hands. But curiosity still overpowered the feeling of fear.
Today, oceanologists, thanks to technological progress and development scientific methods got the opportunity to study the smallmouth macropinna and all other inhabitants previously inaccessible for study depths of the sea.
Fish with transparent head
Macropinna has a transparent forehead, through which some of the insides, and to a greater extent the organs of vision, are visible. When light shines on the barrel eye, its eyes turn a bright green color. Why does this happen? All it's about a special yellow substance, which filters the light that hits the fish. The eyes of the barrel eye are located in the frontal part of the head, in a special compartment that is filled with a special liquid.
If you look at a photo of a macropinna, a logical question may arise: if the fish’s eyes are located right in the head, then why are there holes where the eyes should be?? In fact, these depressions are the barrel eye's olfactory organs. It is with the help of them that the transparent deep-sea inhabitant receives information about changes around him.
These fish have a wide and round body covered with dark, hard scales. The head is dome-shaped, absolutely transparent. Between the barrel eye's eyes is a thin bony septum. The fish's brain is located in its widest part.
Whatever amazing creation No matter the macropinna fish, it will not be able to surprise anyone with its size. Representatives of this species do not have a large body. The largest individuals do not grow more than fifteen centimeters in length.
Habitat
This unusual fish with a transparent head can be found in the subarctic and temperate waters of the Pacific Ocean, namely in its northern part.
Macropinnas live:
- off the coast of northern Japan;
- near the Kuril Islands;
- in the waters of the Bering Sea off the coast of Canada;
- small population of clearheads sea inhabitants also seen near Mexico in the Gulf of California;
- The western shores of the United States are also home to these unusual creatures.
Lifestyle of an extraordinary fish
Macropinna is a deep-sea marine inhabitant; it can be found under the water column, diving to five hundred to eight hundred meters. To the barrel eye could move around calmly at such a depth, nature rewarded these transparent fish special fins that help their owners deftly maneuver and move even under strong pressure.
The digestive system of macropinnas is also designed in a special way. It allows barrel-eyes to easily digest small fish and animals that can be found at great depths.
Macropinna is not particularly active; she prefers to move slowly or even hang in one place without a single movement. But this does not prevent clear-headed fish from being excellent hunters. By using special structure organs of vision, eyes macropinna are capable look not only ahead, like most living beings on the planet, but also up! This amazing feature allows the fish to observe its prey from any hiding place and not lose sight of anyone. When the prey swims too close to the barrel eye, it is immediately captured. Of course, she will no longer be able to escape from the predator’s death grip.
Diet
Scientists have been interested for quite a long time in what these unusual creatures eat. But long years follow macropins there was no opportunity due to the preference of these creatures to live in deep waters. It was also not easy to bring the fish to the surface, since due to the pressure difference their body simply burst, turning all the insides into jelly.
To date, oceanographers and researchers have been able to autopsy the barrel eye and study undigested food debris in the fish’s stomach.
Diet of clear-headed deep-sea fish:
- zooplankton;
- small crustaceans;
- Cnidarians or cnidarians;
- siphonophore tentacles together with cnidocytes.
Cnidocytes are part of the tentacles of organisms belonging to cnidarians. With their help, cnidarians protect themselves from enemies by injecting poison, or catch food. Considering this fact, many scientists have come to the conclusion that the transparent head and the location of the eyes of the macropinna are the result of the evolution of fish to protect the organs of vision from cnidocytes.
Reproduction
The smallmouth macropinna is an inhabitant of the deep sea, where it is rarely found sunlight. Therefore, due to its very secretive lifestyle and habitat scientists are still could not figure out how these amazing creatures reproduce water creatures. Do barrel eyes have natural enemies and who they are, for similar reasons, absolutely nothing is known yet.
We can only hope that someday oceanologists will have the opportunity to more carefully study these animals and answer all the questions they have. About the reproduction of macropinna what is known is that females lay very large quantities of eggs. From it, fry are born with a very elongated body, completely different from the adults of their species. As their bodies develop and appearance undergo many changes, which ultimately transfer the appearance of their parents to the young animals.
Interesting facts about fish with transparent heads
- Macropinna has hypersensitive eyes. Thanks to this feature, she sees very well and navigates at great depths, where they cannot penetrate Sun rays where it's always dark.
- Barrel eyes are very dependent on pressure: the stronger it is, the better they feel. This is the reason why they live in lower layers water.
- With a sharp change in water pressure downward, macropinnas can die. Because of this feature, scientists for a long time could not study this species. sea creatures. Because when smallmouth macropinnas were removed from the water, their heads could not stand it and instantly burst, and the fish immediately died.
- The smallmouth macropine received its name not by chance. Despite the fact that these fish are predators, their mouths are very small. This significantly limits their choice of prey.
- During the day, barreleyes often swim to the top layers of water to search for food. When darkness falls, they return back to the depths. This fact has been confirmed many times by fishermen who periodically find representatives of this species among the caught fish.
At the moment, about ten representatives of the opisthoproctaceae family are known to the world. As habitat they most often choose northern waters Pacific Ocean. Favorite places for the settlement of deep layers are the waters near the shores of Kamchatka, as well as the Bering Strait and the Sea of Okhotsk.
Today, you can meet some representatives of transparent-headed fish in the Californian aquarium. This the aquarium is considered one of the largest structures in the world. It contains ninety-three tanks in which these unusual creatures are kept. Every year more than two million people come here to see the amazing marine inhabitants. Therefore, the California Aquarium is considered one of the most visited places in the world.
Smallmouth macropinna, or barrel eye (lat. Macropinna microstoma) is a species of deep-sea fish, the only representative of the genus Macropinna, belonging to the order Smeltfish. They have transparent head, through which they can see with their tubular eyes. The head, through which the fish watches for prey, helps protect the eyes.
Macropinna microstoma - comparatively small fish, the largest known specimens reached about 15 centimeters in length. The body is covered with large dark scales, the fins are large, wide and rounded. This species is characterized by a long intestine with numerous blind processes, a wide pharynx and a narrow mouth, which is the main limitation on the size of prey suitable for consumption.
First opened in 1939. It lives at very great depths, so it has been little studied. In particular, the principle of fish vision was not entirely clear. It was believed that she must experience very great difficulties due to the fact that she can only see up. Only in 2009 was the structure of the eye of this fish fully studied. Apparently, when trying to study it earlier, the fish simply could not tolerate the pressure changes.
Valuable video captured by underwater vehicles with remote control in 2004, helped biologists understand how the fish species Macropinna microstoma sees and hunts. The fish's tubular eyes and transparent head have puzzled scientists since 1939, when macropinnae were first caught. The process of studying these fish was further complicated by the fact that after Macropinna microstoma entered the net, a “bubble” burst, protecting the head structures from exposure to the external environment.
Previously, biologists had established that the eyes of fish see very well even in almost complete darkness, that is, they successfully collect light. And these representatives of the family Opisthoproctidae live at a depth of 600-800 meters off the coast of Central California.
However, scientists were surprised by the fact that the fish’s eyes look only in one direction, namely upward, to the surface of the ocean, where a potential victim can be detected by its silhouette. Given that macropinnas have a very limited field of vision, biologists could not understand how the fish managed to capture prey with their small mouths.
Bruce Robison and Kim Reisenbichler of the Monterey Bay Aquarium Research Institute (MBARI) showed that macropinna's eyes can still rotate inside a transparent, fluid-filled head. In this way, the fish can concentrate its gaze on the prey it is hunting or eating.
In the video recorded by underwater vehicles, the fish hangs in the water column almost motionless. In the light of the streetlights, her eyes appear bright green. Scientists also saw for the first time that there is that same transparent “shield” around the top of the head, and the cavity under it is filled with liquid.
Robinson and Reisenbichler were doubly lucky: a little later they were able to catch several living specimens of Macropinna microstoma. Over the next hours, the behavior of these fish was studied in a special aquarium, and scientists confirmed their guesses - the tubular eyes rotate when the macropinna changes the position of its body from horizontal to vertical.
Biologists have also discovered other adaptations to the deep-sea lifestyle: wide, flat fins allow very precise maneuvering in the water and the fish’s body remains almost motionless; the digestive system makes it possible to digest many types of small drifting animals. Fragments of the body of jellyfish were even found in the stomachs of two individuals.
Scientists believe that most At the same time, the fish swims in a horizontal position, its eyes turned to the surface. Green lenses can filter incoming sunlight. When an animal that reveals itself by a bioluminescent glow (for example, a jellyfish) floats above it, the fish turns vertically, its eyes begin to look straight, and hunting and feeding begin.
IN digestive system fish of this species were found in zooplankton different sizes, including small cnidarians and crustaceans, as well as siphonophore tentacles along with cnidocytes. Considering that zooplankton in large quantities accumulates on the tentacles of siphonophores, where it can be obtained deep sea fish, as well as the remains of cnidarians found in the digestive system of Macropinna mіcrostoma, we can come to the conclusion that the continuous transparent membrane above the eyes of this species evolved evolutionarily as a way of protecting cnidarians (especially siphonophores) from cnidocytes.
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