Pearl mussels, also called clams. Pearl mussels are named because they are rich in natural pearls. The shell of pearl mussel is large, thick and rectangular. The length, height and width of the shell can reach 180mm, 70mm and 40mm respectively. Shells are relatively large, with dark brown or nearly black surfaces and shiny spots, and generally live in rivers and streams. In China, it is mainly distributed in Heilongjiang, Jilin and other provinces, and also distributed in some reaches of Dalian. Freshwater pearls are also distributed and cultivated in Japan and the former Soviet Union. Most of the pearl components produced by pearl mussels are calcium carbonate, which is not only a beautiful ornament, but also a relatively precious Chinese herbal medicine.
To cultivate pearl mussels, we must first choose healthy and excellent varieties, and then choose suitable waters. We can choose to raise them in ponds or rivers. Generally, the water depth of the pond is about 1.5 meters. Some fish, such as grass carp and loach, can be kept in the pond, and the pH of the pond should be kept in balance. Slight alkalinity is a good state, because acidic water with low pH will affect the growth of pearl mussels and the formation of pearls in the body. In pond culture, water should be changed or added frequently to maintain good water quality and sufficient oxygen. River culture should choose a river with strong mobility, health and no pollution, and sufficient oxygen, which is conducive to the growth of pearl mussels, and then supplement nutrients to pearl mussels through fertilization. The food of pearl mussels is mainly algae, and inorganic fertilizer and organic fertilizer are applied, so that the pearls of freshwater pearl mussels will be larger.
Pearl mussels produce pearls because there is a covering film in their shells. When these membranes are stimulated to a certain extent, they will rapidly divide and proliferate, then gradually surround the stimulation source, then become complete pearl sacs, and then secrete nacre layer by layer, and finally become finished pearls. It usually takes two to three years for pearl mussels to produce pearls. Pearl culture can make pearl mussels produce pearls, but pearl culture is generally carried out in spring or autumn, when the water temperature is more suitable, the wound heals faster and the quality of pearls will be better. Pearl collection of pearl mussels is generally carried out when the water temperature is lower than 20 degrees, and the quality of pearls is better at this time. Pearls, mussels and vegetables are usually cut with knives. Cut the muscles under the shell with a knife, then pick up the pearls, wash them with water, dry them with a cloth, and finally polish them into finished products.