Now we eat crayfish are actually not native to China, it originated from the southeast of the United States, so also known as the American crayfish, introduced to Japan in 1918, as a feed for raising bullfrogs, and then introduced to China by Japan, has now become an important resource in China's freshwater shrimp, widely distributed in the middle and lower reaches of the Yangtze River provinces and cities, crayfish like to live in clean places, crayfish in stinky ditches are not big.
The origin of crayfish
The real name of the crayfish is "Procambarus clarkii", and the scientific name is Procambarus clarkii, which is a freshwater shrimp that is like a fake bag. It is related to lobsters, taxonomically they are "decapods", lobsters are lobster family, orthopedic shrimp family or quasi-crawfish family, and the crayfish we eat are the cockroach family (so in some areas of northern China it is directly called "cockroaches").
Crayfish are native to the southeastern United States, so they are also called American crawfish. Its native land is near the Gulf of Mexico, especially in the mouth of the Mississippi River, so it is also called Louisiana Crawfish. It is the most edible freshwater lobster species, accounting for 70-80% of the total freshwater lobster production.
Crayfish belong to the southern State of Louisiana in the United States, a carrion-eating animal, introduced to Japan in 1918 as a bait for raising bullfrogs, and then introduced to China by Japan, and has now become an important resource in China's freshwater shrimp, widely distributed in the provinces and cities of the middle and lower reaches of the Yangtze River.
In May 2013, it was rumored on the Internet that crayfish were introduced to China by the biochemical forces of the Japanese army invading China to specifically dispose of corpses, which is purely a rumor.
The origin of the crayfish
Crayfish are native to louisiana in the southern United States, and in 1918, Japan introduced crayfish from the United States as a food for raising bullfrogs. According to some data, China did not produce crayfish in the past, the origin of crayfish dates back to the Second World War, the Ubiquitous crayfish (the predecessor of crayfish) that can be found everywhere in Japan, after a series of genetic modifications, Crayfish were transported to the Japanese military station in batches to clean the water body. The improved crawfish showed better ability to adapt to highly corrupt water bodies than its predecessors, stronger reproductive ability, especially the ability to adapt to mineral poisoned water bodies, and the Japanese declassified archives showed that: high nutrition, lung fluke disease and black gill disease in low-oxygen water bodies, Crawfish almost lifelong carry, but the mortality rate is close to normal. During World War II, crayfish were introduced to China from Japan and have now become an important resource in China's freshwater shrimp, widely distributed in the provinces and cities in the middle and lower reaches of the Yangtze River.
Crayfish have a high protein content, accounting for about 16%-20% of the total, the fat content is less than 0·2%, and the content of trace elements such as zinc, iodine and selenium in shrimp meat is higher than that of other foods. However, there is a very important nutrient of crayfish that many people may ignore, that is, astaxanthin, which mainly exists in the shrimp head of the shrimp yellow and the red substance on the shrimp shell, most of the cooking methods may be lost, because astaxanthin is a strong antioxidant, so it is easy to be oxidized. In addition, crayfish can also be medicated, which can dissolve phlegm and cough, and promote the healing of wound muscles after surgery.
Crayfish growing environment
Every year from June to August, when the crayfish is at its most "plump", it is also the best time for people to catch and enjoy it. Green artemisia grass, shallow water beach, this water is where Lao Gan often catches lobsters.
Shrimp farmers say that crayfish like to live in clean places, and in places like stinky gutters, crayfish don't grow much.
Why do crayfish in crimson can survive in large quantities in dirty silt, while pale red shrimp are not easy to survive even in clear water?
Scientific research has proved that the astaxanthin content of the body is positively correlated with its ability to resist the harsh environment outside, which means that the higher the astaxanthin content of the body, the stronger its ability to resist the harsh environment outside. The natural astaxanthin content in the body of the jujube red color crayfish is several times that of shrimp. Therefore, dark red crayfish can survive and multiply in dirty silt, while pale red shrimp are not easy to survive even in clear water.
Crayfish are omnivores, mainly eating plants, small fish, shrimp, plankton, benthic organisms, algae can be used as its food. The reproductive capacity of crayfish is not strong, and crayfish are bred once a year.
Did China have crayfish before?
In fact, there are four kinds of original and authentic crayfish in China, which are northeast black crayfish, Nanjing black crayfish, Shi's crayfish and Korean black crayfish. In addition, there are two kinds of "foreign monks", the original Crawfish of the United States and the red crayfish native to Oceania, but the protocrayfish of Klesi has a higher skill, blooming everywhere in the land of China, becoming the most famous crayfish.
Now the edible crayfish is during the Second World War crayfish introduced to China by Japan, began to breed in Nanjing, Jiangsu Province and suburban counties, after a long period of expansion, the number of populations continues to increase, living space continues to expand, the current crayfish has expanded to Anhui, Shanghai, Jiangsu, Hong Kong, Taiwan and other places, the formation of a large number of natural populations, become an important resource in China's freshwater shrimp.
So the delicious crayfish we eat is actually an invasive species, this shrimp is fierce, fast-breeding, and extremely adaptable to the environment.