Eriocheir sinensis (), commonly known as hairy crabs. Although their prices in China are staggering, they are actually an arthropod with strong viability. Eriocheir sinensis, a typical omnivore, mainly feeds on various aquatic plants, but also feeds on various insect larvae, snails, shellfish, small fish and carrion. They have seized the niches of many local species, and often can successfully crowd out their competitors in water with scarce food. Moreover, the Chinese mitten-handed crab has a strong mobility. According to the report of Greenwich residents in London, England, the Chinese mitten-handed crab was seen leaving the Thames for the bustling business district. There are also reports that Eriocheir sinensis has occupied private swimming pools. Of course, Eriocheir sinensis is not strong enough to migrate from China to Europe across the Eurasian continent. It is believed that they went to Europe on a European merchant ship at the beginning of last century. Of course, the way they stay in the ocean is not very glorious. After all, they are illegal immigrants. When the ship is empty, the center of gravity of the hull is high, and it is easy to capsize when it encounters heavy waves. In order to solve this problem, empty ships will load ballast in the ship to lower the ship's center of gravity. Water is one of the most commonly used ballast, also known as ballast water. As a ballast, the density of ballast water is not high, but the biggest advantage is that it can be loaded and unloaded at any time-but a large number of local species may be brought in when loading ballast water, and these animals and plants will be taken to the corresponding places when unloading. Eriocheir sinensis was smuggled to Europe by hiding in ballast water. Moreover, the main reason for the flood of Eriocheir sinensis in Europe is the lack of natural enemies. Like other crabs, the thick armor provides them with good protection. In Europe, only some local fish, such as eels, perches and yarrow fish, prey on Eriocheir sinensis, which has just changed its shell and is still soft, and herons occasionally eat hairy crabs for meat. However, the Chinese mitten-handed crabs lacked hard shell protection for a short time, and soon they returned to an almost invincible state. In fact, there are not many natural enemies of Eriocheir sinensis in China, except human beings. The German "eating goods" means eating only meat without bones (the answer in the reference), so it's no wonder that Eriocheir sinensis is rampant. Besides crowding out native species, Eriocheir sinensis also has the habit of digging holes and nesting.