<h1 class="pgc-h-arrow-right" > introduction:</h1>
What is Wenchang Fish? In fact, it is not a fish, but a creature on the earth that plays an important role in the evolution of species, known as the "living fossil" of species evolution.
amphioxus
< h1 class="pgc-h-arrow-right" > Wenchang fish is not a fish</h1>
Fish on earth is one of the animals, and those with "fish" in the name are not necessarily fish, such as crocodiles are reptiles, and octopuses belong to mollusks. Of course, Wenchang fish is no exception, to be precise, it is like a worm, it is a kind of "worm" with high protein like a bee pupa. The Wenchang fish is a transitional species of cephalopod evolution into vertebrates. The chordate phylum consists of 3 subphylums: the subphylum cephalozoa, the subphylum caudosum, and the subphylum vertebrates. We humans belong to the vertebrates, and the human spine is like a bamboo knot, section by section. Modern fish are also mostly vertebrates. The Phylum Chordata is one of the most evolutionarily advanced phylums in the animal kingdom. Chordates have three major characteristics: they have a chord, they have a dorsal neural tube, and they have a fissure in the throat.
Wenchang fish existed on earth 500 million years ago, with an elongated body, pointed ends, a flat back, and a broad abdomen. There are "<" shaped muscle segments on the side of the body, overlapping left and right. dioecism. The body is translucent, shiny, with clear reproductive glands, about 4 cm long. The mouth is hidden inside the mouth, and there are 38 to 50 marginal membrane tentacles on the edges of the mouth. The half-cut body is buried in the sand, only the front end is exposed to the sand, and the half-cut body hides in the sand during the day, relying on the water flow to bring plankton and diatoms for food. Wenchang fish have higher environmental requirements and live in sea areas with a water depth of 8-15 meters, clear water quality, slow flow and sandy substrate. It has no visible eyes, not even a head in the strict sense of the word. To be precise, it is not a fish at all, and it does not have a real brain.
Anatomical diagram of Wenchang fish
So why is it called Wenchang fish?
<h1 class="pgc-h-arrow-right" > the origin of the name of Wenchang fish is related to Zhu Xi</h1>
Wenchang fish is commonly known as slugs, sea worms, pine carriers, headless fish, crocodile worms, double-pointed fish or sea spears. When it comes to Wenchang fish, many people have words such as Wuchang fish and Wenchang Pavilion in their minds. Wuchang fish is bream, and Wenchang Pavilion is the ancient official school site (similar to modern universities). The origin of the name of Wenchang fish is really related to Zhu Xi, folk legend Zhu Xi is "Wenchang Emperor", folk legend zhu Xi in addition to crocodile essence story, and Wenchang fish is also named because of this story. The common name "crocodile worm" about Wenchang fish also comes from such legends.
During the Shaoxing period of the Southern Song Dynasty, Zhu Xi went to Tong'an County, the capital of Quanzhou, as the chief bo, and often heard that crocodiles were refined into white women to sneak into the county to harm people. Once, Zhu Xi was writing a letter under the lamp, when he heard a gust of wind, he looked up and found a woman with suspicious behavior. Wondering if this was the legendary evil crocodile spirit, he hurriedly threw the cinnabar pen in his hand, and the tip of the pen was stabbing the navel of the woman in white. The woman in white escaped with her wounds, and early the next morning, Zhu Xi led people to search for blood to trace them to the seashore of Liu Wudian, and found that a small island floated on the surface of the sea, which was the body of a crocodile spirit. Today, the name crocodile island in the Xiamen sea is derived from this. The larvae that grow on the body after the death of the crocodile spirit are crocodile worms.
Xiamen Crocodile Island
In fact, it is not only Xiamen that produces Wenchang fish. Shandong Qingdao, Yantai), Hebei (Qinhuangdao), Guangdong (Shantou, Yangjiang, Maoming, Zhanjiang), Hainan and other coastal areas; Japan, Western Europe, North America and other seas have also found this species, but only Xiamen Liu Wudian sea area has a fish flood, is the world's wenchang fish fishing ground, fishing history has been 200 to 300 years of history. Wenchang fish, daguiyuan and Shoushan stone carvings are collectively known as the Three Treasures of Fujian. Wenchang fish has a delicious taste, high nutritional value, protein content of up to 70%, rich in iodine, has obvious effect on thyroid disease.
<h1 class= "pgc-h-arrow-right" > the biological evolutionary status of Wenchang fish</h1>
The morphological structure of Wenchang fish is very special, with the characteristics of both invertebrates and vertebrates, which is a typical representative organism of invertebrate evolution into vertebrates, and is a rare marine animal with research value.
Compared to vertebrate fish, Wenchang fish have no real eyes; no heart, the abdomen has a strong aorta to replace the function of the heart; there is no real head, simple enough to have only one brain vesicle; no spine, only a rod-like cord; no upper and lower jaws, more primitive than the jawless lamprey.
In terms of translucency, some real fish are significantly different from Wenchang fish in the above biometrics. Such as the glass cat in the ornamental fish, the blind fish living in the cave, the silver fish living in the river are vertebrate, they are real fish, they are real vertebrates.
Although the glass cat is all transparent, it has all the characteristics of a fish, with a head, eyes, fins, vertebrae, and five organs.
Glass cat
The big silver fish is also a fish in the full sense.
Big silver fish
The blind fish in the cave are translucent compared to the Wenchang fish, but they are also fish in the true sense.
Blind fish, silver fish and Wenchang fish
<h1 class="pgc-h-arrow-right" > how do Wenchang fish prey on and digest food? </h1>
The Wenchang fish does not have the ability to catch food on its own, but can only rely on drinking algae like drinking water, and its gill cavity is like a net that can filter the detritus and organisms in the water.
Most animals digest and absorb food, but Wenchang fish have a different digestive pattern. The intestines of Wenchang fish use a single cell to wrap algae particles for material digestion. And this digestive cell has immune genes, which can kill some harmful bacteria.
<h1 class="pgc-h-arrow-right" > resource conservation of Wenchang fish</h1>
Wenchang fish is a second-class protected animal in China. Because of people's over-mining of beaches, habitats have been polluted and destroyed, and the amount of fish resources in Wenchang has been greatly reduced. Xiamen Liu Wudian Crocodile Island coastal area is China's Wenchang fish rich production area, but also the only formation of fishing grounds in the sea area, due to the construction of embankment reclamation, resulting in seawater flow direction, flow rate, salinity, substrate changes, resulting in a large number of Wenchang fish deaths. In order to save this special species of Wenchang fish. China has established the Wenchang Fish Ecological Reserve.
For example, the Qingdao West Coast National Marine Park Conservation Area has been established in the Qingdao sea area near the Bohai Sea, which is an important protected area for marine biological resources such as Wenchang fish, wild ginseng, and wrinkled pan abalone.