Coelacanth-like
A general term for some bony fishes of the order Crossopterygii. The related but extinct Rhipidistia species is considered as the ancestor of terrestrial vertebrates. In some classification systems, coelacanth and fanfin are considered to belong to different orders in the subclass Crossopterygii. Modern coelacanth is a kind of deep-sea fish in the family Brachytidae, so it is named because of its hollow fins. Bigger than most fossil species. It is a fierce predator, with a thick and sticky body, four-legged fins and flexible movements. Coelacanth appeared 350 million years ago, when it was extremely abundant on the earth. The coelacanth fossils were found from the end of Permian (245 million years ago) to the end of Jurassic (65.438+44 million years ago). Like other similar fish, coelacanth has a low degree of ossification, showing a general trend of leaving the early freshwater environment and turning to the marine lifestyle. For a long time, coelacanth has been thought to be extinct about 60 million years ago, but in 1938, a living species Latimeria chalumnae was captured in the coastal waters of southern Africa. Under the reward collection, 1952 caught a second tail (named Malania anjouanae, probably the same species as pike) in Comoros Islands. Later, several people were arrested in this area. Later, it was discovered that this kind of fish has long been familiar to islanders. Its meat can be eaten after being salted and dried, and the coarse lodicule is used as grinding material.
Coelacanth, also known as coelacanth, is named after its hollow spine. Because scientists can't find its trace in the strata after Cretaceous, they think that the hero who landed in Latimeria chalumnae has passed away and become extinct. 1938, one day near Christmas, Marjorie Courtenay-Latimer, a staff member of the South African Museum, discovered the fish caught by fishermen near the Comoros Islands in southern Africa, which attracted worldwide attention. This fish should be a coelacanth in the total fin (the same kind with fringed fins) that appeared about 350 million years ago and died out 65 million years ago. Total fin fish can not only breathe air, but also walk with fins as feet, which is an important evidence for the evolution of fish to amphibians. During the Devonian period 400 million years ago, the ancestors of coelacanth climbed onto the land with strong fins. After a period of struggle, one of them became more and more adapted to land life and became a real quadruped. The other suffered setbacks on land, returned to the sea again, found a quiet corner in the ocean and bid farewell to land completely.
The so-called coelacanth is believed to have first appeared in Devonian 350 million years ago. It once flourished and distributed in many places. But from the middle of 654.38 billion years to the end of Mesozoic 75 million years ago, it began to decline, and its traces disappeared from the earth, leaving only fossils.
This quiet corner is 1 1000 meters deep. As we all know, it is more difficult for human beings to enter the sea than to ascend to the sky. First of all, great pressure: every time the water depth increases by 1 0m, the pressure will increase by1atm. At the depth of 1 1000 meters, the pressure will be as high as 1 100 atmospheric pressure, not to mention human flesh and blood, even ordinary steel members will be crushed to pieces. And the harsh environment under the sea: dark and cold! Sunlight enters the sea and is quickly absorbed. The light energy at10m is only 18% of the ocean surface, and it is only 1% at the depth of100m. The light is scarce, the heat is naturally difficult to stay, and the cold and darkness under water can be imagined. However, coelacanths usually live in very deep seabed and hide themselves in caves of rocks on the seabed. In the harsh underwater world, they aimed at survival, constantly put pressure on themselves, learned to get along with the pressure, and lived painfully and happily in the history they created, which lasted for 400 million years beyond imagination!
Coelacanth
This is the oldest known fish in the world. Before being caught by fishermen in 1930, everyone thought this fish was extinct. Scientists originally thought that coelacanth only lived in eastern Africa, but in 1997, another related species, Latimeria menadoensis, was discovered in Sulawesi, Indonesia.
. From May 65438 to June 2007, Zanzibar (also translated as Zanzibar) was located in an Indian Ocean coastal city on an island in eastern Tanzania, East Africa. Fishermen caught a coelacanth, which lived in the fish pond of a seaside restaurant for 17 hours. Scientists in France, Japan and Indonesia have dissected the coelacanth, and they are going to analyze its genes.
Since this fish was caught near the beach with a water depth of only 105 meters, scientists will next study whether the Indonesian coelacanth lives in shallower waters than the African coelacanth.
Discovered story:
1938 One day, a trawler caught a strange fish in the sea near East London, South Africa. This is a big fish about two meters long with green light. Scales cover the whole body like armor, and sharp fish heads are extremely hard. What is particularly striking is that it has two fat and thick shark fins on its chest and abdomen, which look like limbs of wild animals. Unfortunately, the fishermen did not give special "care" to this strange-looking fish, but mixed it with other catches and transported it back to the port and piled it on the dock.
At this time, Ms. Latima, who works in the East London Museum, happened to pass by the pier. When she saw the fish, she couldn't help but stop: she was interested in a 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. When she got home, Ms. Ladima found all the books about fish, but she couldn't find the name, illustrations and descriptions of the fish. She went to the library again, hoping to find the answer, but she searched all the professional books and pictures of fish in the collection and found no clues about this fish. The result of nothing inspired Ms. Ladima's determination to find out the ins and outs of this fish. So she wrote a letter to Professor Smith, a famous South African ichthyologist, and attached her own sketch to ask the professor for advice.
Professor Smith, who received the letter, exclaimed when he saw the sketch of the fish: "Isn't this a coelacanth?" This is an ancient coelacanth! But it has been extinct for tens of millions of years. Is there anyone left? This is incredible! " The professor immediately sent a telegram to Ms. Latima: This fish is very similar to the ancient coelacanth. I'll come to your place right away. Please take good care of that fish. After sending the telegram, the excited professor immediately drove to East London.
No wonder Ms. Ladima searched all the data and found no results. It turns out that this strange fish is called coelacanth, which flourished 300 million years ago, but after it evolved from a marine animal to a land animal, it returned to marine life for some reason and disappeared tens of millions of years ago. Today, people's understanding of coelacanth comes from fossils. They think coelacanth has disappeared from the earth forever.
When Professor Smith arrived dusty, he was greatly disappointed with what he saw: all he saw was some fish bones, fat shark fins and green scales-after receiving the professor's telegram, Ms. Latima flew to the dock, but unfortunately, the ignorant fishermen had eaten the fish.
Professor Smith, who was in high spirits just now, has no strength to speak now, and the fatigue of the journey of more than 500 kilometers has also come up at once. Although the bones, fish scales and shark's fin are preserved, which is helpful for the study of coelacanth, it has lost its complete research object! The professor affirmed that this fish is a coelacanth that can only be seen in fossils in the past. He thinks that at least one fish is still alive, because a fish can never survive after tens of millions of years of changes. Only after several generations of reproduction can it survive to this day. But where are the other coelacanths?
Professor Smith immediately printed a large number of leaflets with images of coelacanth, and wrote in English, French and Portuguese: "Anyone who finds this fish will be rewarded with 100", which was widely distributed along the Pacific coast of Africa. The professor himself went to find, investigate and publicize to the fishermen by fishing boat. Despite the hardships and efforts, there is still no sign of coelacanth.
Soon, when the Second World War broke out, the whole world was involved in the whirlpool of war, and the search for coelacanth was gradually forgotten. Professor Smith didn't forget or lose heart. When the long war had just ended, he immediately began to look for coelacanth. ...
After years of hard work, no clues to coelacanth were found. This is February 1952. So, why did Professor Smith spare no effort to find coelacanth? As we all know, all animals on land evolved from the ocean. In the process of evolution to land animals, aquatic animals without limbs, such as fish, have given birth to limbs and returned to live in the ocean. Scientists call this aquatic animal "coelacanth". If the evolution of fish living in the ocean into land animals is compared to the growth of frogs, then coelacanth is completely equivalent to tadpoles with limbs. Professor Smith thinks that if we find coelacanth, we will probably find the key to the mystery of biological evolution.
Is coelacanth really extinct? And which one was the only one found at that time? Just when the professor was close to despair, a telegram came to him from far away: "We caught a fish that looks like a coelacanth and look forward to your arrival." This telegram was sent by fishermen in Comoros Islands. The pleasantly surprised professor hurried to the South African government for help and flew to Comoros by military plane. Yes, this is the professor's dream coelacanth: this "living fossil" with a length of one meter and fifty centimeters and a weight of 58 kilograms was injected into formalin and then pickled, waiting for the arrival of the professor.
In the evening, Professor Smith, still immersed in excitement and joy, put the box containing coelacanth on his bedside-after a long and hard search of 14 years, he finally got the result today. The professor whose long-cherished wish was realized was deeply moved and stayed up all night. ...
A fisherman in Indonesia recently caught a coelacanth. This kind of fish is an ancient fish in the dinosaur era and was once considered extinct.
Scientists say: "once the coelacanth leaves the living waters, it can only survive for about two hours." However, this coelacanth caught by fishermen survived 17 hours. "
Before 1938, most scientists thought that coelacanth was extinct as early as 80 million years ago. Until 1938, a living coelacanth was found in South Africa. Since then, coelacanth has been called "the living fossil of dinosaur era".