First, prawns belong to arthropod crustaceans, and there are many kinds. Including green shrimp, river shrimp, grass shrimp, crayfish, prawns (Penaeus vannamei, Penaeus vannamei, China prawn, and Bohai Bay _ Niudao prawn), prawns, metapenaeus ensis, mussels and lobsters. Among them, prawn is a special product of our country, which is named prawn because it is often sold in pairs in a big sale. Shrimp live in warm sea, and can live and breed in Bohai Bay in summer and autumn. In winter, shrimp have to migrate to the waters with high seabed temperature in the southern Yellow Sea to avoid the cold.
Second, the activity ability of shrimps in winter is very poor, and they don't prey. Every March, shrimps scattered around the country begin to concentrate and swim to the north in droves. After two months' travel, they arrived in the shallow sea near the Bohai Sea and began to breed. Female shrimps were exhausted after a long journey, and most of them died after laying eggs. Only those with strong physical strength could continue to survive. The body structure of newly hatched shrimps had to undergo many changes, and it took more than 20 molts to grow into adult shrimps. Male shrimps mature that year, and female shrimps will not mature until the next year. Shrimp has slender tentacles twice as long as its body, which are used to sense the surrounding water. Strong muscles in its chest are conducive to long-distance migration. The tail fan of the abdomen can be used to control the balance of the body, and it can also bounce back.
Third, the prawn is long and flat, and the exoskeleton is calcareous, which is divided into two parts: the chest and the abdomen. The head and chest are covered with carapace. The abdomen consists of seven body segments. At the front end of the head breastplate, there is a serrated forehead sword and 1 pair of compound eyes with handles that can rotate. Shrimp breathes through gills, which are located on both sides of the head and chest and covered by crustaceans. The mouth of the shrimp is at the bottom of the head and chest. There are two pairs of antennae in the head and chest, which are responsible for smell, touch and balance, and there are also chewing devices composed of jaws. There are also three pairs of jaw feet in the head and chest to help hold food, and five pairs of walking feet, which are mainly used for hunting and crawling.
Four, there are five pairs of swimming limbs and a pair of short tail limbs in the abdomen. The tail limb and the last section of the abdomen are combined into a tail fan, which can control the swimming direction of shrimp. It is a Crustacea, Decapoda, Natantia, with nearly 2,000 species. It is closely related to crab, crayfish, _ _ _, sea crayfish, cicada shrimp and lobster. It is characterized by translucent body, flat side, flexible abdomen and tail fan at the end. The second antenna is long and whiplike. Abdominal limbs are swimming limbs. Ocean and fresh water lakes and streams. Many kinds are important foods. The size ranges from several meters to several millimeters, with an average of 4~8 cm. The big ones are called prawns. You can swim backwards quickly by bending your abdomen and tail. Eat tiny creatures, and some eat carrion. Female shrimp can lay 1, 500 ~14,000 eggs, which are attached to swimming limbs. There are five developmental stages before adulthood.