Largemouth shark June 3rd, 2017
We've already been with you a lot . But as it turns out, that's not all. Look what passion is still floating in the oceans. Let's study this “beauty”.
After 1976, it became clear that there were now not two, but three species of plankton-eating sharks in the world. The first two are and giant shark, and the third was a largemouth shark. Legends and myths of many coastal peoples contain stories about encounters between people and huge sea monsters. Among them there are also references to a large fish: half whale, half shark. On November 15, 1976, a fabulous legend came to life: one of the American ships was pulled out of the depths of the sea amazing shark with a huge mouth.
Let's take a closer look at it...
The discovery occurred on November 15, 1976, completely by accident, when a US Navy hydrographic ship was conducting its research in the area Hawaiian Islands. On that day, the ship was above a depth of 4,600 meters and therefore could not release a conventional anchor. We decided to lower 2 parachute anchors. After completing the research, when they were picked up, they found in one of them unusual fish huge size. It turned out to be a 446-centimeter largemouth shark, whose weight reached 750 kilograms. This giant fish was transferred to the Honolulu Museum.
After a thorough study of the animal, it became obvious that this is a shark unknown to science, which was given the name pelagic largemouth shark (lat. Megachasma pelagios ). Why the “big mouth” is clear to anyone who has at least once seen it in photographs: a round head with a mouth of incredible size immediately catches the eye. But it became “pelagic” due to its habitat - it is believed that these sharks live in the mesopilagic zone, i.e. at a depth of 150-500 meters.
That's it, for some time there was no more hearing or spirit about this shark. But after 8 years she made herself known again. The second largemouth shark was caught off Santa Catalina Island, California, in November 1984. This copy was sent to the Museum natural history Los Angeles. And then a whole series of similar discoveries began.
Over the next 30 years, scientists were able to examine less than three dozen specimens.
Between 1988 and 1990, 4 more sharks were discovered (1 on the coast of Western Australia, 2 on the Pacific coast of Japan and 1 in California), and in 1995, 2 more specimens (near Brazil and Senegal). And so on until 2004. In total, about 25 specimens were observed between November 1976 and November 2004, the largest of which was a shark found dead in April 2004 on the shore near the city of Ichihara in Tokyo Bay. Its length was 5.63 meters. It was a female. The smallest shark was a male, caught on March 13, 2004 near the island. Sumatra. Its length was 1.77 meters. Another specimen was caught by Philippine fishermen in 2005.
The most outstanding part of this shark's body is its incredibly large mouth. The color is not much different from other types of sharks - dark gray or dark brown. The belly is much lighter than the back.
Since all sharks belong to the class cartilaginous fish, then she was no exception. The largemouth skeleton consists of soft cartilage, and the tissues are highly saturated with water. As a result of this, the shark is not able to develop decent speeds when swimming, so its approximate speed is only about 2 km/h.
At the very beginning of the note, we already mentioned the specifics of her diet. The main food of the largemouth shark is plankton (crustaceans, jellyfish, etc.), of which special preference is given to reddish euphausiid crustaceans, also known as krill, that live at shallow depths. A largemouth shark, having stumbled upon a school of krill, opens its mouth and sucks in a large volume of water and, pressing its tongue to the palate, squeezes the water out through closely spaced gill slits. The krill's escape route is blocked by numerous small teeth. After straining the water, the shark swallows everything that remains in its mouth.
Despite the fear of the terrible word “shark,” this species does not pose a danger to people. The largemouth shark has a particular predilection for krill, descending after it during the day to a depth of 150 meters and rising to a depth of 15 meters at night. In any case, this is how the male largemouth behaved, which was caught in 1990. Scientists made a film about him, equipped him with a radio transmitter and released him to observe his migratory behavior for almost two days.
Only a little over 30 years have passed since the discovery of this wonderful fish. During this time, biologists were able to find out only a small part large mouth life. The shark lives in all oceans, with the exception of the Arctic. Most common in southern hemisphere globe. Frequent encounters with fish took place nearby Japanese islands and Taiwan, which led scientists to assume that largemouths are prone to warm waters. Specimens were also caught near the Hawaiian Islands, Ecuador, South Africa and Australia, which confirms the hypothesis of the “heat-loving” animal.
Mating, according to biologists, occurs in the fall off the coast of California, because that is where the most mature males were found. Like many other sharks, the greatmouth shark is ovoviviparous.
Huge mouth with numerous small teeth
The shark's head has a huge mouth, which is how it got its name. She filters the water with her mouth, leaving only plankton in her mouth, which she feeds on. Since plankton is found predominantly in the upper layers of water, it may seem that the fish are staying on the surface, but this is not entirely true. Fishermen also caught largemouths at depths exceeding 200 m. Such vertical migration is common for planktivorous animals that move through the water column following food.
According to unconfirmed reports, it is believed that the largemouth shark can live at depths of 1 km. Proof of this hypothesis can be the body structure characteristic of deep sea inhabitants. It is soft and flabby, and the mouth is surrounded by photophores, which can serve as bait for small fish and plankton. The presence of photophores is generally characteristic only of deep-sea fish.
The shark swimmer is not important. A largemouth shark moves with average speed only 1.5-2 km/h. The body is dark, brown-black above and white below. Its coloration resembles that of a killer whale, so observers could sometimes mistake the largemouth for a young killer whale. This is also facilitated by the presence of small teeth in the shark’s mouth.
On this moment The pelagic largemouth shark is a virtually unstudied animal. Too few individuals caught the eye of the researchers, because diving to the depths favored by largemouth is not so easy. For the same reason, it is unknown whether the species is in danger of extinction. The mighty ocean reliably keeps its secrets.
Mysterious Largemouth
Family Megamouth sharks (Megachasmidae)
Genus: Megamouth sharks (Megachasma)
Largemouth shark
(Megachasma pelagios)
Largemouth shark, or largemouth shark (lat. Megachasma pelagios) - one of three known to science species of plankton-eating sharks (besides the whale and basking shark). Since its discovery in 1976, this deep-sea shark has remained the only kind in the family of largemouth sharks (lat. Megachasmidae). No more than three dozen specimens of this amazing and very large fish have been in the hands of scientists.
There is still very little information about the anatomy, lifestyle and distribution range of this shark.
It is impossible to say for sure whether people encountered this species in previous centuries and whether it gave rise to legends about sea monsters that are a mixture of a whale and a shark.
The first specimen of this shark was caught on November 15, 1976 off the island of Oahu in Hawaii at a depth of 165 meters, after which it was described. It was a 4.46m long male that was caught by an American research vessel after he tried to bite through the cables that were lowered into the water and got stuck in them. The fish were brought ashore because the crew decided that they were interesting material for research.
The animal was carefully studied, and today it is stuffed in the Honolulu Museum.
The second sample was caught in 1984, at a shallow depth (38 m), not far from Santa Catalina Island. It was a male 450 cm long. His stuffed animal is currently on display in the museum.
The third specimen of largemouth washed up in shallow water in 1988. off the coast of Australia - surfers, mistakenly deciding that it was a whale, tried to drag it to the depths in order to save it. The third individual was also a male, 515 cm long.
The fourth and fifth samples were caught in Japan, the fourth - in the winter of 1989, the fifth was caught alive in the net, after which he was released.
The sixth sample caused a real sensation because it was captured alive and scientists were able to study it. On October 21, 1990, scientists near California managed to catch a living male five meters in size. He was caught near Los Angeles and transferred to a research center. It was a five-meter male, who was placed on an ultrasonic transmitter and released. The fish were observed for the next 50 hours. The study results showed that these sharks, like many other species, use vertical migration. The fish spent the daytime at a depth of about 170 m, and at sunset it rose to a depth of about 12 m, and stayed there all night. This vertical migration coincides with the vertical migrations of shrimp, which are included in the diet largemouth shark.
Largemouth sharks are easily recognized by their huge round head and large mouth located on the front of the head. Inner side The mouth is silvery, the jaws are covered with many small hooked teeth. There are relatively large nostrils on the front side of the snout.
The eyes are round. small. Behind the head are five pairs of long gill slits.
The largemouth shark has two dorsal fin- large anterior, small posterior and long pectoral fins. The ventral and anal fins are smaller. The powerful caudal fin has a heterocercal shape - its upper lobe is much longer than the lower one.
The body coloring is discreet and does not have any spots, stripes or patterns. The color varies from gray to brown or blue-black on the back, and from ashen to pale gray on the belly.
The largest specimen measured was a dead female measuring 563 cm, which washed ashore on April 19, 2004 near the city of Ichihara in Tokyo Bay. The smallest specimen was a male 177 cm long, caught on March 13, 2004 near the island of Sumatra.
Most notable external sign, to which the largemouth shark owes its name, is a relatively large, rounded head with a short nose and a huge mouth. The huge mouth of a fish reveals its food preferences - its design resembles the structure of the mouths of baleen whales, whale sharks and giant sharks. Having collected water into its huge mouth, the predator squeezes it through a sieve of teeth and gill rakers, sending the edible contents into the stomach.
Largemouth sharks were found in the Atlantic, Pacific and Indian Ocean. Apparently, their habitat is very extensive. However, individuals were most often caught off the coast of California and Japan. After analyzing the places where these large marine predators were caught, scientists came to the conclusion that this species is distributed throughout the World Ocean, preferring relatively warm latitudes.
Estimated range of the largemouth shark
Mating appears to take place off the coast of California in the fall, as this is where the largest number of mature male largemouth sharks have been found.
The largemouth reproduces by ovoviviparity; the characteristics of reproduction and the number of cubs in the litter are unknown.
For humans, this species of shark is not dangerous (as are whale or basking sharks), but, like any large animal, this fish should be treated with caution. With a slight movement of its tail, it can seriously injure a swimmer. However, a meeting of a person with this shark in the sea is an unlikely occurrence.
Studies of the stomach contents of dead largemouth sharks have shown that the diet of this fish is based on small organisms - zooplankton, for example, krill. Unlike the basking shark, which only passively filters water containing plankton, the greatmouth shark is able to actively suck in water for filtration. It is still unknown whether these animals also eat small fish. The feeding method of largemouth sharks resembles that of a whale - teeth and gill rakers form a mesh filter that filters plankton, shrimp, crustaceans, animal larvae, and small jellyfish from sea water, which serve as food for the predator.
Megamouth shark stranded on April 20, 2002 off the coast of Nature's Valley (33* 59" S, 23* 34" E), in the Western Province of South Africa. At first she was mistaken for whale shark, but later it turned out that it was a megamouth shark.
This was the 17th largemouth shark discovered by scientists, counting from one caught in the fall of 1976 in Hawaii.
The shark's body was frozen and transported to Port Elizabeth for study by scientists. The shark was well preserved; it turned out to be a female about 4 meters long. After studying and examining the shark's body by scientists, a stuffed animal was made from it for the museum. This is the first largemouth shark discovered off the South African coast in the western Indian Ocean.
The largemouth shark is quite rare - it lives in sea waters, at a depth of 150 - 1000m. In length, judging by the size of the caught specimens, it can reach 6 meters or more, with males being smaller than females.
The fact that so large creature first discovered in the waters of the World Ocean quite recently, once again speaks of how little we have yet studied our planet and how many more discoveries await us...
Peculiarities
The largest specimen measured was a dead female measuring 5.63 m, which washed ashore off the city of Ichihara in Tokyo Bay on April 19. The smallest specimen was a male caught on March 13, 2004 near the island of Sumatra, whose size was 1.77 m. The most noticeable external feature, to which the largemouth shark owes its name, is a relatively large rounded head with a short nose and a huge mouth. Her back is dark brown, her belly is lighter. The largemouth shark has two dorsal fins, one asymmetrical caudal fin, two large pectoral fins and two belly fins, of which the posterior pair is much smaller.
Spreading
Largemouth sharks were found in the Atlantic, Pacific and Indian Oceans, most often off the coast of California and Japan. From this, biologists conclude that this species is distributed throughout the world and prefers relatively warm latitudes. Mating appears to take place off the coast of California in the fall, as this is where the largest number of mature male largemouth sharks have been found.
Nutrition
Studies of the stomach contents of deceased animals have shown that the largemouth shark's main food is small organisms such as krill. Unlike the basking shark, which only passively filters water containing plankton, the greatmouth shark is able to actively suck in water for filtration. Whether these animals also eat small fish is still unknown.
Behavior
On October 21, scientists near California managed to catch a living male five meters in size. For the first time, a largemouth shark was able to be equipped with a radio transmitter and released into freedom. Thus, the first data on the migratory behavior of the shark, including its vertical movements, were obtained. It became known that the largemouth shark spends the night at a depth of about 15 meters, and during the day it descends to a depth of 150 meters. Presumably, the shark follows
After 1976, it became clear that there were now not two, but three species of plankton-eating sharks in the world. The first two were basking sharks, and the third was a largemouth shark. What surprised everyone about this fish, I think, is clear from its name. The shark's large head ends in a mouth of incredible size, which opens much wider than that of all other shark species.
The discovery occurred on November 15, 1976, when a US Navy hydrographic ship was conducting research in the Hawaiian Islands. On that day, the ship was above a depth of 4,600 meters and therefore could not release a conventional anchor. We decided to lower 2 parachute anchors. After completing the research, when they were raised, they found an unusual fish of enormous size in one of them. It turned out to be a 446-centimeter largemouth shark, whose weight reached 750 kilograms. This giant fish was donated to the Honolulu Museum.
That's it, for some time there was no more hearing or spirit about this shark. But after 8 years she made herself known again. The second largemouth shark was caught off Santa Catalina Island, California, in November 1984. This specimen was sent to the Los Angeles Museum of Natural History. And then a whole series of similar discoveries began.
Small copy 
Between 1988 and 1990, 4 more sharks were discovered (1 on the coast of Western Australia, 2 on the Pacific coast of Japan and 1 in California), and in 1995, 2 more specimens (near Brazil and Senegal). And so on until 2004. In total, about 25 specimens were observed between November 1976 and November 2004, the largest of which was a shark found dead in April 2004 on the shore near the city of Ichihara in Tokyo Bay. Its length was 5.63 meters. It was a female. The smallest shark was a male, caught on March 13, 2004 near the island. Sumatra. Its length was 1.77 meters. Another specimen was caught by Philippine fishermen in 2005.
The largest specimen 
The smallest specimen The most outstanding part of this shark's body is its incredibly large mouth. The color is not much different from other types of sharks - dark gray or dark brown. The belly is much lighter than the back.
Gray color Since all sharks belong to the class of cartilaginous fish, she was no exception. The largemouth skeleton consists of soft cartilage, and the tissues are highly saturated with water. As a result of this, the shark is not able to develop decent speeds when swimming, so its approximate speed is only about 2 km/h.
At the very beginning of the note, we already mentioned the specifics of her diet. The main food of the largemouth shark is plankton (crustaceans, jellyfish, etc.), of which special preference is given to reddish euphausiid crustaceans, also known as krill, that live at shallow depths. A largemouth shark, having stumbled upon a school of krill, opens its mouth and sucks in a large volume of water and, pressing its tongue to the palate, squeezes the water out through closely spaced gill slits. The krill's escape route is blocked by numerous small teeth. After straining the water, the shark swallows everything that remains in its mouth.
Huge mouth with numerous small teeth 
Open mouth The largemouth shark is a pelagic fish, that is, it lives in the mesopilagil zone (depth 150-500 meters). At night it rises closer to the surface, and during the day it goes deeper.
This shark lives in the warm latitudes of 3 oceans: the Atlantic, Pacific and Indian, but most often it can be found off the coast of California and Japan.
Habitat 
Mating, according to biologists, occurs in the fall off the coast of California, because that is where the most mature males were found. Like many other sharks, the greatmouth shark is ovoviviparous.
IN sea depths such fish as the largemouth shark live. Its habitat covers tropical, subtropical and temperate regions of the World Ocean. Despite the fact that the name contains the word “shark,” this species feeds only on plankton, small fish and jellyfish. The fish swims with an open mouth, which is enormous in size, and obtains food by sucking and filtering water.
These remarkable marine inhabitants became known only in November 1976, when the first such fish was caught near Hawaii. It reached 4.5 meters in length and weighed 750 kg. This find became a sensation in ichthyology of the last century. And her stuffed animal was placed in the Honolulu Museum.
To date, this species has been poorly studied, since it rarely comes into view of people. A little more than a hundred of these sharks were caught, and only a few of them were examined by specialists. The body is black-brown above, the belly is light. The tail has a larger upper lobe and is generally similar to the tails of other shark species.
The muzzle is wide and rounded. The mouth is large with small teeth. It is surrounded by luminous photophores (special glands) that attract plankton and small fish. The mouth of a largemouth shark reaches a width of 1.3 meters. There are 50 rows of teeth in the upper jaw, and 75 in the lower jaw. The gill slits have an elongated shape. The skin is relatively soft. These fish grow up to 5.7 meters in length. Weight reaches 1.2 tons.
Puberty in males occurs at a body length of 4 meters, in females the corresponding value is 5 meters. This type refers to viviparous. But extremely little is known about reproduction based on the few specimens of both sexes captured.
Largemouth sharks feed at depths of up to 1500 meters. The most optimal depth for them is 120-170 meters. And only occasionally do representatives of the species rise to a depth of 40 meters, and in shallow bays they can even be found at a depth of 5 meters. This makes it clear why they so rarely catch the eye of people.
In the water column, this fish opens its huge mouth wide and swims through the accumulation of krill. From time to time she closes her jaws and squeezes her throat tightly to compact the food. After this, it is swallowed, and the mouth opens again to swallow the next portion of krill. For more efficient hunting, the jaws have the ability to move forward. This allows the fish not to wait for the food to swim into its mouth, but to suck it in.
To study the behavior of this species, a 5-meter largemouth shark was caught in California waters in 1990. A sensor was placed on her body and she was released. He transmitted information about the depth and speed of movement for 2 days. During the daytime it showed a depth of 120-160 meters. At night the fish rose to a depth of 12-25 meters. At the same time, she swam all the time at a speed of 1.5-2.1 km/h. This picture is common for many sea creatures, which track plankton in the water column.
Despite the fact that sharks of this species have large sizes, they do not pose a danger to people. It should also be noted that they are not in commercial demand. Judging by the reviews, their meat is quite edible, but does not have high taste qualities. If this fish accidentally gets caught in the net, it is usually thrown overboard.
The only people who are interested in representatives of the species are ichthyologists, as well as workers of aquariums and museums. There is no information on the number of largemouth sharks.
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