CATDOLL : CATDOLL: Why do river clams produce pearls?

Why do clams produce pearls?

Why can river clams produce pearls? The pearls produced by river clams can be processed into various decorations and handicrafts. Pearls are also precious medicinal materials. They can be made into powder and then mixed with other substances to form various Chinese patent medicines such as pearl powder, pills, pills and liquids. So why can river clams produce pearls?

Why do river clams produce pearls?

There are about 20-30 species of pearl oysters, but not every oyster will produce pearls. Pearls are only produced when parasites or foreign objects such as sand and gravel enter the oyster's body. When the oyster feels the stimulation, it will immediately secrete a kind of nacre from the mantle. So when we break the clam open, we can see the inner layer of the clam shell, which is often smooth and bright, and emits a pearl-like luster. This is the nacre.

Therefore, most artificially produced pearls are made by placing a core made of clam shell in the mantle tissue of the clam, which makes it difficult for the clam to spit it out. After a long period of friction and nacreous wrapping, artificially cultivated pearls are formed. This method is used to produce pearls in the coastal areas of my country. However, these mass-produced pearls are often not round and smooth enough, and because the molding time is very short, the price will not be very high.

However, as the breeding technology becomes more and more advanced, now artificial breeding can cultivate not only ordinary pearls, but also colorful and image pearls. The different organic metal elements contained in the pearls will show different colors, such as yellow, green, white, blue, etc. Generally, those cultivated in fresh water are purple-red and pure white.

What kind of oyster shell has pearls?

The triangular fan clam is the main pearl oyster in my country. It is widely distributed in the shallow waters of my country's lakes. It mainly feeds on plankton. It has a triangular shape with a sail-shaped wing protruding from the back. It has a brown or black shell that is very hard and thick, about 20 cm long. The pearl production of this triangular fan clam is significantly higher than others, and the quality is also good.

There is also a kind of pond clam imported from Japan, which is also a freshwater pearl oyster living in lakes. It is about 23 cm long. Because of its well-developed mantle muscles, the pearls it produces are large and round, and the quality is particularly good. It belongs to the same family as the triangular fan clam, but there are white marks on the top of the shell, which will fall off when it grows up. The clam shell is brown and the inside has a bluish-white luster.

Why can river clams produce pearls 2 The main reason for pearls to grow in river clams is the invasion of parasites or foreign objects. When small foreign particles accidentally enter the body of the river clams, the river clams cannot expel the foreign objects in their bodies in time. After being stimulated by the invasion of foreign objects, the mantle of the river clams will soon secrete nacre, and the nacre will gradually surround the invading foreign objects. Over time, the foreign objects will be coated with a thick layer of nacre, thus forming an exquisite and lovely pearl.

It does not mean that the bigger the clam shell, the bigger the pearl inside. This is determined by the length of time that the foreign object has been in the clam shell. The longer the time, the bigger the pearl. The body surface of the river clam has two thick backs. On the inner surface of the two backs, there is a soft membrane called the outer membrane. The covering wraps the soft body of the river clam. The outer shell on the surface of the river clam is formed by the secretion of the mantle.

The mussel has a fleshy axe foot in the front of its body. When the environment is quiet, the river clam slightly opens its back and extends its axe foot. The muscle contraction of the axe foot allows the river clam's body to move slowly. When the clam is disturbed, the axe foot immediately retracts and the back closes tightly to protect the soft body. When we were young, we often went to the river to catch mussels and put them on the windowsill to dry for a while. The shell opens, extends the fleshy axe foot, and moves slowly, but the river clam cannot leave the water and stay in the sun for too long, so the mussel will die soon.

In addition, the mantle of the mussel can secrete nacre, forming bright nacre on the inner surface of the shell. When the mantle is stimulated by foreign matter such as sand, the mantle will secrete a large amount of pearls to wrap the foreign matter, thus forming dazzling pearls. The pearls formed in this way are a small number of natural pearls. Pearls can not only be used as beautiful ornaments, but also have medicinal value and sedative effects.

In order to meet the huge demand for pearls, people use the principle of pearl formation, through certain surgical treatment, to implant artificial pearl nuclei into pearl oysters, and then put the pearl oysters back into the water for breeding, so as to obtain a large number of artificially cultured pearls. China is the first country in the world to artificially culture pearls. The method of artificially culturing pearls was invented as early as the Song Dynasty. Artificial pearl breeding in my country has developed rapidly.

Why can river clams produce pearls? 3 The reason why pearls grow in clams

Because the shells of clams growing in water are often invaded by parasites or sand, they cannot expel the parasites or sand. In order to protect the body from harm, the mantle secretes nacre to surround it layer by layer, and over time, pearls are formed. People use this habit of clams to cultivate pearls artificially.

What do river clams eat to grow pearls?

River mussels mainly live in rivers, lakes and other freshwater lakes. They are a kind of shellfish food. River mussels usually replenish their energy by absorbing some water and nutrients from aquatic plants. River mussels feed on organic particles, rotifers, flagellates, algae, small crustaceans, etc.

Under accidental conditions, when tiny irritating foreign matter enters and contacts the mantle of the river clam, it does not react like most of us - to expel the matter from the body. Instead, its mantle secretes a kind of nacre that wraps these tiny matter layer by layer to form growths, and after a certain period of time, pearls are formed.

River clams are omnivorous animals that live in water. They feed on organic particles, rotifers, algae, small crustaceans, etc. They replenish nutrients and energy through water and aquatic plants. The formation of pearls is a kind of excretion secreted by their mantle.

Knowledge of mussel farming

1. The water surface cannot be too small, requiring more than 6000m2. If the area is too small, the water quality environment will change greatly and be unstable, which will affect the growth of clams.

2. Pearls can be bred in waters with a depth of 1.5-4.0 meters, preferably 2-3 meters. It is not suitable to breed pearls if the water depth is less than 1 meter or more than 5 meters.

3. The water source is sufficient and free of pollution, and the content of toxic substances shall not exceed the fishery water quality standards.

4. Flowing water at a certain speed (no more than 0.1 meters per flow) is beneficial to the growth of oysters and pearls. Production practice has shown that oysters can produce 5-8 grams of pearls per pearl in one year in rivers and lakes with flowing water and good conditions, while it takes 3 years to produce 5-8 grams of pearls per pearl in still water.

5. Adequate sunlight can directly produce a thermal effect, thus providing energy for pearl oysters and their bait organisms. Light also has a direct impact on the color and luster of pearls. It can increase the dissolved oxygen in the water, promote the movement of water bodies and the transfer of heat.

6. Clay is the best soil for pearl breeding waters, followed by river soil, and loess and sandy soil are the worst. There should be appropriate silt at the bottom of the pond.

7. The pH value of 7-8 is most suitable for the growth of pearl oysters and the secretion of nacre.

8. The dissolved oxygen content in water should generally be greater than 5 mg/L in summer and greater than 3 mg/L in winter.

9. The transparency of clam waters is best at 30 cm.

10. The optimum water temperature range for clams is 18-28℃.