The coelacanth is the general name of coelacanthes with leaf fins and hard bones. It is about 1.5 meters long, spindly, covered with thick scales, with small spines attached to the scales. Two fat and strong fins, like limbs, are grown on the chest and abdomen respectively, compared with other fishes, and the tail has redundant round projections.The coelacanth has a rare intracranial joint in other fishes. It can raise the front of its head at will. The front and rear nostrils are opened above the head, which is not related to breathing.[6]
The coelacanth was found in the oceans all over the world during the Devonian period,[7]The living coelacanthes are generally the largest deep-sea fishes with a body length of more than 2 meters, but in the early days, coelacanthes were small fishes that lived in shallow water and freshwater waters, with a body length similar to goldfish and crucian carp.[8]The coelacanth is a typical night owl. It hides in a cave during the day and comes out to hunt at night, mainly feeding on small fish, squid and octopus.The reason for vision is that it can only catch the prey in front of its mouth and ignore the prey in other directions.Not only that, you can still see things normally in the dark ocean,[9]The breeding speed is relatively fast, and the environmental adaptability is relatively strong.[10]
The coelacanth is believed to be the earliest aquatic organism, and the first fish to land and grow feet. It has lived on the earth for 400 million years, and is known as the "living fossil of the dinosaur era".[6]The coelacanth is fleshy, and was once the favorite and most common prey of hunters in that period.[10]People have only found coelacanth fossils before, thinking that they had become extinct at the end of the Cretaceous Period. Today, coelacanth only has one family, the lancet family, which has not yet become extinct. They live in the deep sea 150~700 meters deep.[8]
Coelacanthiniteleost fish(bony fish)。Once thought to haveExtinction60 million years.In 1938AfricaSome live coelacanthes were found after the discovery of lancetail (Latimeria chalumnae) in the southeast waters.The fish is very heavy and 1.5 meters long.The head is short and the fins are limb shaped. It can crawl on the sea floor and feed on other fish.Order: Crossopterygii.[1]
History of Ethnology
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Coelacanth
Very oldfingerlingIt can be traced back to 400 million years. The coelacanth, once considered extinct, was rediscovered in 1938.
One day in 1938, in South AfricaEast LondonOn the nearby sea, aTrawlerA strange fish was caught.This is a big fish about two meters long with blue light,scaleIt is covered all over the body like armor, and the sharp fish head is extremely hard. What is particularly striking is that it has two fat and strong fins on its chest and abdomen, which look like the limbs of a wild animal.Unfortunately, the fishermen did not give special "care" to this strange fish. Instead, they mixed it with other fish and transported it back to the port and stacked it on the dock.
At this time, Ms. Radima, who worked in the East London Museum, happened to pass by the dock. When she saw the fish, she couldn't help but stop: she was interested in the fish with "limbs" that she had never seen before, so she took out her notebook from her satchel and drew the shape of the fish.Back home, Ms. Ladima found out all the books about fish, but neither the name, atlas or description of the fish was found.She came to the library again, hoping to find out the answer. But she searched all the professional books and fish atlases in the library, and found no clue about the fish.The result of nothing inspired Ms. Radima's determination to find out the ins and outs of this fish.So, she sent a letter to Professor Smith, a famous South African ichthyologist, and attached her own sketch to ask the professor for advice.
Specimen of coelacanth
When Professor Smith, who received the letter, saw the sketch of the fish, he cried out, "Isn't this a coelacanthancient extinct lifeThe coelacanth!But it has been extinct for tens of millions of years. Can it survive?This is incredible! "The professor immediately sent it to Ms. Radimatelegraph: This fish is very similar to the coelacanth of paleontology. I will go to your place right away. Please take good care of that fish.After sending the telegram, the excited professor immediately drove his car to East London.
No wonder Ms. Ladima has searched all the data and found no results. It turns out that this strange fish is called coelacanth, which was once prosperous 300 million years agomarine animalTo terrestrial animalsevolutionFor some reason, it has given birth to limbs and returned to live in the sea, and has disappeared tens of millions of years ago.People's understanding of coelacanth today is based onFossilThe coelacanth has disappeared from the earth forever.
When Professor Smithbe travel-stainedWhen the ground arrived, the professor was disappointed by what he saw: all he saw was some fish bones, fat fins and still green scales. After receiving the professor's telegram, Ms. Ladima flew to the dock. Unfortunately, the fishermen had eaten the fish.
Professor Smith, who was still in high spirits just now, has no strength to speak now, and the fatigue of the long journey of more than 500 kilometers has also sprung up.Although bonesscaleThe shark fin has been preserved, which is helpful for the study of coelacanth, but it has lost a complete research object!The professor confirmed that this fish was the only fish in the pastFossilThe coelacanth seen on.He believes that at least one fish is still alive, because it is absolutely impossible for only one fish to survive after tens of millions of years of changes. It can only survive after generations of reproduction.But where are the other coelacanthes?
Professor Smith immediately printed a large number of leaflets with the image of coelacanth, and wrote in English, French and Portuguese: "If you find this fish, you will be rewarded with 100 pounds", which is widely distributed in the Atlantic Ocean of Africa and along the coast of the Indian Ocean.The professor himself also went to the fishing boat to look for and investigate with the fishermen.Although we have tried our best, we still haven't seen any coelacanth.
Coelacanth
Soon,the Second World WarWhen it broke out, the whole world was involved in the vortex of war, and the search for coelacanth was gradually forgotten.Professor Smith did not forget, nor was he discouraged. When the long war was just over, he immediately began to look for coelacanth.
After years of hard searching, no clue of coelacanth has been found.By this time, it was December of 1952.So why did Professor Smith spare no effort to find the coelacanth?We know that animals on land come from the seaevolutionIn the process of evolution to land animals, aquatic animals without limbs like fish have given birth to limbs but returned to live in the sea. Scientists call this aquatic animal "coelacanth".If we compare the evolution of fish living in the sea to land animals to the growth of frogs, the coelacanth is just like a tadpole giving birth to limbs.Professor Smith believes that if you find the coelacanth, you will probably find the openingBiological evolutionThe key to the mystery gate.
Coelacanth
Did the coelacanth reallyExtinctionDid you?And the one found at that time was the only one?When the professor was almost in despair, a telegram from afar was sent to him: "We have caught a fish like a coelacanth, and we look forward to your arrival." The telegram wasComoros IslandsFrom fishermen.Surprised, the professor hurried to ask the South African government for helpMilitary aircraftFly to the Comoros Islands.It's true, this is the professordream ofThis coelacanth is 150 cm long and weighs 58 kg“living fossil”Was injectedformalinThen he salted it again, waiting for the arrival of the professor.
In the evening, Professor Smith, still immersed in excitement and joy, placed the box containing the coelacanth beside his bed. After 14 years of hard searching, today we finally got the result. The professor who had fulfilled his long cherished wish was filled with emotion and stayed up all night
morphological character
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Coelacanth
Modern coelacanth isSpeartailThe deep-sea fish of the family Latieriidae is named for its hollow fins and spines.Its body size is larger than that of most fossil species.It is a fierce predator with thick body and mucus, limb like fins and flexible movements.The color is bright and easy to distinguish.
Habitat environment
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Coelacanth
Many living coelacanth individuals have been found, confirming that at least two coelacanth species of the same genus still exist in the world.For example, in July 1955, German scientists found at least 15 such fish at a depth of 150-270 meters off the coast of the Comoros Islands in the Indian Ocean;In 1997, a related species of coelacanth was found on Sulawesi Island, Indonesia;In July 1998, Indonesian fishermen caught coelacanth with deep water shark nets, which is about 10000 kilometers away from the habitat of coelacanth colony in the West Indian Ocean;In 2010, a team found coelacanth in Sodwana Bay, South Africa
Indonesian coelacanth is obviously different from Comoros coelacanth - the latter is blue, while the former is brown.Therefore, the coelacanth found in Indonesia in 1999 was described asNew species。The existing coelacanth mainly belongs to the genus Spermopterus, which isLungfishAnd a close relative of four limbed mammals.
The coelacanth is widely distributed, but it began to decline from 100 million years ago to 75 million years agomesozoicAt the end of the period, its trace disappeared from the earth, leaving only fossils.
This is the oldest living fish in the world today. Before the fishermen caught two of them in the 1930s, they thought that this fish was extinct.Scientists thought that coelacanth only lived in eastern Africa, but in 1997, in IndonesiaSulawesi（Celebes）Another related species, Latimeria menadoensis, was found.May 16, 2007ZanzibarZanzibar is located in the Indian Ocean coastal city on an island in eastern Tanzania, East Africa. Fishermen caught a coelacanth, which lived for 17 hours in the fish pond of a coastal restaurant.Scientists from France, Japan and Indonesia have dissected coelacanth, and plan to carry outGene analysis。
Since this fish was caught near the beach and only 105 meters deep, the next thing scientists need to study is whether the habitat of Indonesian coelacanth is shallower than that of African coelacanth.
The coelacanth lives in a cave at the bottom of the sea. It has a short head and limb like fins. It can crawl on the bottom of the sea and feed on other fish. A single coelacanth can reach 1.8 meters long and weigh 90 kilograms.[3]
Very slow growth
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The research shows that the growth rate of coelacanth is extremely slow. The female coelacanth will become sexually mature at the age of more than 50 years, while the male coelacanth will become sexually mature at the age of 40 to 69 years.Scientists also studied two coelacanth embryos and calculated that the largest one has developed for 9 years and the smallest one has developed for 5 years.Scientists believe that female pregnancy can last for at least five years.Slow growing fish are more vulnerable to climate change and overfishing.[4]
Population status
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Latimeria chalumnae
Before 1938, most scientists believed that coelacanth had been extinct 60 million years ago.Until 1938, whenSouth AfricaFound live coelacanth.
Coelacanth
The so-called coelacanth is believed to have first appeared 350 million years agodevonian, once prosperous, distributed in many places.Coelacanth“Empty ratchet”, English name (coelacanths), named after the hollow spine.Because scientistsCretaceousNo trace of it can be found in the later stratum, so it is believed that this landing hero has left the world and is completely extinct.In 1938, one day near Christmas, in southern AfricaComoros IslandsNearby, Marjorie Courtenay Latimer, a South African museum member, discovered it when she was inspecting the fish caught by fishermen, which attracted worldwide attention.It is speculated that this fish is a coelacanth among the total finned species (the same species with spike side fins) that appeared about 350 million years ago and disappeared 65 million years ago.totalFinfishThe fish can not only breathe air, but also use fins to walk as feetAmphibianevolutionImportant evidence.400 million years agodevonianAt that time, the ancestors of coelacanth climbed onto the land with their strong fins.After a period of struggle, one of them became more and more adapted to land life and became a true quadruped;The other group suffered setbacks on the land and returned to the sea again. They found a quiet corner in the sea and bid farewell to the land completely.
Protection level
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Coelacanth
Some conservation work on coelacanth has been carried out.For example, the Convention on International Trade in Endangered Species ordered the trade of coelacanth to be prohibited.Now, a new protection measure may soon come into effect: the National Marine Fisheries Service (NMFS) proposed to list coelacanth as a "near threatened" species under the Endangered Species Act (ESA) in early March this year.
A fisherman in Indonesia recently caught a coelacanth.This fish isThe age of dinosaursAn ancient fish that was once considered extinct.
The scientist said: "Once the coelacanth leaves the water where it lives, it can only survive for about two hours. However, the coelacanth caught by the fishermen survived for 17 hours."
It was previously thought that the longest life span of coelacanth was 20 years, but this assumption was related to the low oxygen uptake capacity of coelacanththe new supersedes the oldSlow, low reproductive capacity and other biological characteristics are inconsistent, causing researchers' concern.[3]
Coelacanth
On June 17, 2021,Marine evolutionary ecologist of the French Institute of OceanographyBruno Hernand[3-4]Researchers reported in Current Biology, a journal of Cell Press Cell Press, that there is evidence that coelacanth can live for a long time in addition to its huge size - probably nearly a century.[2]Scientists usePolarizing microscope, found coelacanthscaleMany of them are only usefulPolarizationCan be seen.A thick line on the scale of coelacanth, which was previously considered（Fishwheel pattern[3]）In fact, it is composed of five thin lines, and each thin line represents one year old.Therefore, the age of coelacanth can approach one century.[4]
world record
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Recently reported existing coelacanthes:A relative species of coelacanth was officially announced in 1999.Before that, the only known coelacanth was the lancetail reported in 1938.Previously, it was believed that these primitive fish had been extinct 65 million years ago.The scales of coelacanth are very hard, which is said to be 10 times harder than ordinary glass.(Guinness World Records)[5]
