Coelacanth (Latimeria Chalumnae)

Coelacanth (Latimeria Chalumnae)
Coelacanth (Latimeria Chalumnae)

Video: Coelacanth (Latimeria Chalumnae)

Video: Coelacanth (Latimeria Chalumnae)
Video: Finding the Coelacanth | DinoFish 2024, March
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The discovery of the coelacanth (West Indian Ocean coelacanth), the only living representative of the Celacanthus order and the cross-finned superorder, was the most amazing event in the history of ichthyology. Cisfeins lived in the ocean 360 million years ago, and 80 million years ago, it was believed, completely died out.

Much has been written about their "resurrection". The first fish was caught on December 22, 1938 in a bottom trawl off the east coast of South Africa, off East London, near the mouth of the Chalma (or Chalumna) river. After this first find, Professor J. Smith was looking for fish for 14 years, and the second specimen was caught only in December 1952 - it turned out that a permanent population of coelacanths lives in a small area off the three Comoros - Gran Comoros, Moheli and Anjouan, in western Indian Ocean. And the first fish caught just accidentally swam into the waters of South Africa.

Comorian coelacanth, or coelacanth (Latimeria chalumnae), drawing picture
Comorian coelacanth, or coelacanth (Latimeria chalumnae), drawing picture

Coelacanth (Latimeria chalumnae)

However, in 1992, one coelacanth was caught from southern Mozambique, and the other was caught in 1995 off the south-western part of Madagascar. It is believed that coelacanths are carried there by the powerful Mozambican current. True, the Madagascar authorities have long been convinced that coelacanth is found off the coast of their country and even ordered the image of this fish on a postage stamp. Of course, there is coelacanth - with every right to it - on the postage stamps of the Comoros.

Scientists are constantly monitoring the state of the Comorian population. Since the mid-80s. employees of the Institute of Physiology of Behavior. Max Planck (Germany), under the guidance of the zoologist H. Fricke, regularly descend on an underwater vehicle to a depth of about 200 m and conduct a census of all living fish. To recognize each of them "in the face" allow light spots scattered on the grayish-blue background of the body.

Lobe-finned fish, or choanic (Sarcopterygii)
Lobe-finned fish, or choanic (Sarcopterygii)

Related article Lobe-finned fish, or choanic fish (Sarcopterygii)

During the observations, it turned out that the coelacanth is nocturnal, descending to hunt to depths of 700 m or more. With the onset of day, the fish return to underwater caves located at a depth of 150-200 m. Celacanths are surprisingly good at controlling their seemingly awkward and heavy body. They can swim both backwards and with their belly up, they can stand on their heads or lie with their belly on the bottom … But, as it was believed earlier, they most likely cannot crawl along the bottom with the help of their powerful fins.

Head of coelacanth (Latimeria chalumnae), photo photograph of ancient fish
Head of coelacanth (Latimeria chalumnae), photo photograph of ancient fish

Coelacanths are slow fish. Most of the time, they seem to soar in the water, using the sea currents along the slopes of the islands. However, even "hovering", the fish easily go around obstacles and perfectly orient themselves in the surrounding space, using electroreception for this purpose.

When actively swimming, coelacanths use paired (especially pectoral), second dorsal and anal fins. The paired fins kick from top to bottom during acceleration, and the fish moves like a hydrofoil. To turn around, the coelacanth presses one pectoral fin to the body and straightens the opposite ones. The powerful blow of the tail fin is used only during a quick dash. When the coelacanth swims, striking with paired fins, they do not work synchronously, like in other fish, but alternately, like the legs of terrestrial tetrapods: left, right pectoral and right abdominal, and then vice versa. Fins also work in lung-breathing fish.

The total number of coelacanths in 1989-1991 remained, although small, about 200-300 specimens, but stable. However, by 1994, the number of observed fish began to decrease. Researchers believe that the most likely reason for this is illegal fishing of the most strictly protected species.

However, locals do not specifically catch coelacanths, since they are not very edible, but they regularly throw fishing rods in those places where it lives. And once it is hooked and pulled to the surface, the coelacanth dies, even if it is immediately released. At one time, in order to preserve the amazing fish, international organizations bought outboard motors for fishermen and installed buoys with bait for fishing various fish far from the coast, over depths that are too deep for coelacanth. However, by 1994, most of the engines were out of order, the fishermen still had nothing to buy new ones, and they again began to fish more and more often near the coast - where they could reach with the oars. Then Frike and his colleagues suggested moving the baited buoys even closer - to places that were already too small for coelacanth …

Comorian coelacanth, or coelacanth (Latimeria chalumnae), photo photograph of ancient fish
Comorian coelacanth, or coelacanth (Latimeria chalumnae), photo photograph of ancient fish

The interest of local residents in preserving coelacanths also increases income from the tourism business. So, in one of the villages, a special center has already been organized, in which visitors are told about amazing fish, and in front of the mouth of one of the caves, in which the coelacanth hides during the day, an underwater television camera has been installed, which allows tourists to watch the hero of the story with their own eyes.

And one more absolutely incredible event that happened in 1997-1998. allows us to hope that the coelacanth can be saved. The fact is that coelacanth was caught ten thousand kilometers from the Comoros, in the Celebes Sea off the coast of Indonesia.

Passion around coelacanth (Latimeria chalumnae)
Passion around coelacanth (Latimeria chalumnae)

An article on the subject of Latimeria chalumnae

In September 1997, the wife of the ichthyologist Erdman, walking through the market in the city of Manado (Sulawesi Island), saw a strange fish that was being transported on a cart. The woman immediately recognized the coelacanth, photographed it and, after asking the fishermen about where they caught the fish, sent a message to her husband. It is interesting that the first specimen of coelacanth was accidentally discovered among fishermen by a woman, curator of the museum Miss Latimer - it was in her honor that the fish got its name.

Comorian coelacanth, or coelacanth (Latimeria chalumnae), drawing picture
Comorian coelacanth, or coelacanth (Latimeria chalumnae), drawing picture

Erdman himself arrived in Sulawesi with a grant from the National Geographic Society. And on July 30, 1998, in front of his eyes, coelacanth was caught off the coast of the young volcanic island of Manado Tua. It was a medium-sized fish - 124 cm long and 29.2 kg in weight (the largest specimens from Comoros reach 180 cm in length and weigh about 95 kg). Outwardly, she was no different from the representatives of the Comorian population, only the color of her body was not steel-bluish, but brown. However, after death, Comorian coelacanths often turn brown. The shape and character of the location of the spots on the body of the newly caught coelacanth were the same as in the Comorian fish. So, most likely, we are talking about the same species.

It is clear that the coelacanth could not simply swim with Comoros in the vicinity of Sulawesi. By the way, local fishermen told scientists that they have known this fish for a long time and call it "raja laut" - the king of the sea. So there is no doubt that Indonesia has its own coelacanth population. It is possible that fish are found on the slopes of the volcanic islands of the northern and western parts of the Indonesian archipelago. DNA analysis should show how much the Sulawesi coelacanth differs from its Comorian counterparts. If the differences turn out to be insignificant, it will be possible to assume that these two populations are not completely isolated genetically, which means that the cross-finned fish can live in some other places in the Indian Ocean. Amazing discoveries are yet to come.

Source: N. Yu. Feoktistova, association of pedagogical publications "September First"

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