China did not produce crayfish in the past. The origin of crayfish can be traced back to World War II. The Japanese biochemical troops stationed in China had to deal with a large number of corpses. However, considering the energy consumption of complete incineration in a crematorium, It was too big, and if primary cremation was used and then broken down into small pieces for discharge, it would cause serious eutrophication of the surrounding water bodies. Therefore, the Japanese thought of the crayfish (the predecessor of crayfish) that could be seen everywhere in Japan at that time. , after a series of genetic modifications, crayfish were transported to Japanese military bases in batches and took on the task of cleaning water bodies.

The improved crayfish shows better ability to adapt to highly corrupted water bodies than its predecessors, and has stronger reproductive capabilities, especially its ability to adapt to mineral-poisoned water bodies. The Japanese side Declassified files show that crayfish carry paragonimiasis and black gill disease in highly nutrient-rich, low-oxygen waters almost for life, but the mortality rate is close to normal values. However, even if lead, mercury, arsenic and other serious teratogenic chemical elements accumulate in the body of crayfish to hundreds of times the normal value, there are no large-scale genetic mutations in the offspring. (Experience has proved the Japanese research results. Rivers in various districts and counties in the south have experienced serious pollution many times, and even loaches have not been spared. However, I have observed polluted rivers many times and only saw one among the dead fish and shrimps. Only dead crayfish.)

From then on, the crayfish survived in mainland China by feeding crazily on the uncremated corpses of Chinese people, and retreated with the surrender of the Japanese army. **The crayfish brought by the military have not faded out of mainland China. On the contrary, the crayfish eat decaying animal carcasses, plankton poisoned by excessive use of DDT by farmers, and the excrement of various animals. and domestic waste discarded by humans, gradually developed and expanded, and finally spread all over the country today. In every small river with zero visibility, and in every sewage outlet of every chemical plant and septic tank, you can see the slow progress of crayfish. figure, and eventually became a delicacy for Chinese people: crayfish.

There are quite a few people who like to eat shrimps. I used to be very fond of it, but after having a meal with someone from Shanghai Entrepreneurship and Environmental Protection Corporation, I have never eaten that thing again. (Note: The main business of environmental protection is sewage treatment.) People from the head office said that Ma Xiao was cultivated by Japanese people with the purpose of using it to treat urban sewage, and was an important participant in the first treatment process. The dirtier the water and the higher the heavy metal content, the moister Ma Xiao will live, and the cleaner the water, the faster Ma Xiao will die. Later, Ma Xiao was introduced to China, and Entrepreneur Environmental Protection also used this heavy metal cleaner. I only ate half of that meal and ended it hastily. I am determined to die, but this year Ma Xiao is particularly popular and everywhere. I saw it with my own eyes at the restaurant on Miyun Road the day before yesterday. When I was waiting for the food, I heard many people ordering, and they were all enjoying their food. The taste is really hard to imagine. Everyone, please don’t eat crayfish. It grows in ditches. The worse and dirtier the growing environment, the more vigorous its vitality. Today’s crayfish are all artificially farmed, but have you ever seen the crayfish farming environment? In order to make the crayfish grow big and fat, shorten its growth period, and satisfy the greed of the poor inland people who deceive themselves because they cannot afford seafood, those black-hearted shrimp farmers use large leather pipes to pour chemicals into the pond. Lead, mercury, domestic garbage, and even more, metal oil. After the crayfish continue to absorb nutrients, the black garbage originally output from the leather tube becomes cleaner and cleaner in the pool, and the more food it eats, the more The more lobsters, the fatter they will be. It's absolutely true. A friend of mine was at Xinhuanet. He secretly followed and took photos and hoped to publish them for everyone. However, the editor-in-chief of Xinhuanet intercepted the photos. Later, this friend got angry and said, "I went to Guijie Street to treat the editor to some sesame seeds in the evening. Guess what the editor said: If you want to harm me, just say so!" After saying that, he made vomiting gestures again and again.

Origin: Central and South America and northeastern Mexico.

Distribution status in China: It has expanded to Anhui, Shanghai, Jiangsu, Hong Kong, Taiwan and other places, forming a large natural population.

Causes and harms of introduction and spread: It is now farmed all over the world and has formed a huge wild population. my country introduced it from Japan in the 1930s and 1940s, and Japan introduced it from the United States earlier, mainly for food and pets.

Procambarus clarkii are often mixed in crop (such as rice) fields. There is no need for artificial incubation. Once the original seeds are put in the pond, it can be self-sustaining. After harvest, there is no need to put the original seeds again. Escaped individuals survived by digging holes in the dikes. They can survive in temporary water bodies and have a wide range of food habits. They can establish populations very quickly and spread easily. It is extremely threatening to local fish, crustaceans, and aquatic plants and destroys the local food chain; it directly causes catastrophic damage to crops (especially aquatic and semi-aquatic crops such as rice) and natural vegetation because of its feeding on the root system; and the construction of holes causes irrigation. Loss of water and destruction of fields; because crayfish have a very complex diet, it will have a certain impact on the growth of fry and the cultivation of first-year-old fish, and will also harm the artificially bred young clams