What's the difference between clam and clam?

There are two kinds of clams, one is mud clam and the other is sand clam. I didn't know these differences before, until I went to a distant fishing village to play, because I went to the sea to find all the food every day. From then on, I knew the difference, but I remember that clams are rough and have no delicious feeling. When a clam is cooked, it sticks out a long tongue-shaped thing.

Scapharca subcrenata (Mollusca), bivalve, Ranunculaceae, Ranunculaceae, is a kind of marine economic shellfish. Distributed in the western Pacific coast of Japan, Korea and China. In China, it is distributed in the Yalu River in the north and Guangxi in the south, especially in the shallow water areas such as Laizhou Bay, Bohai Bay, Liaodong Bay and Haizhou Bay.

The characteristic shell of Scapharca subcrenata is thick and wide, and the double shell bulges; The left shell is slightly larger than the right shell. The front end of the belly edge of the shell is round, and the back end is slightly long and oval. There are about 32 convex and dense radial ribs on the surface of the shell, and small square nodules can be seen on the ribs, which is more obvious on the left shell. The shell surface is covered with a brown fluffy epidermis, which is the name of the clam.

Biological characteristics Scapharca subcrenata lives in muddy sediments with a water depth of less than 20 meters in shallow water, especially at a water depth of 2 ~ 10 meters; It is also often distributed in the lower intertidal zone. Buried shallowly, it generally deepens with individual growth, and the depth is about 3 ~ 10 cm. It is suitable to inhabit the inner bay with proper inflow of fresh water. Generally, the salinity is 265,438+0 ~ 28.8, and the water temperature varies from 0 ~ 32℃, so it belongs to a wide temperature species. Feeding on organic detritus of phytoplankton.

Scapharca subcrenata is dioecious, and the sex ratio is 1: 1. The gonads of the second-instar shellfish began to mature. The female gonad is orange, and the male is milky white, which is more obvious when it matures. The breeding period is mostly from July to September; The water temperature is 25 ~ 27℃ and the salinity is 23.5 ~ 28.8. 3.5 ~ 4.0 cm long shells can ovulate 2.5 ~ 3 million at a time. Mature eggs are round. The egg diameter is 62 ~ 73 microns. Sperm is tiny, with a total length of only over 40 microns. In the process of reproduction, sperm and eggs are discharged at the same time and fertilized and developed in water. Within 2 days, the shell formed. After 10 days, the shell grew to about 300 microns, and it changed from plankton to attached organisms. The secreted foot silk attached to underwater gravel, shells and macroalgae, which could cut off crawling activities, and then secreted the attached foot silk separately. Some young shellfish with shells several millimeters long are attached to other things with foot silk. The growth rate of Scapharca subcrenata is related to the temperature, salinity and bait in the living waters. 1 The age increases the fastest, with an annual increase of 2.3 cm; The 2 nd instar shell is 3.7 cm long; After 3 years, the shell is 4.6 cm long; The growth rate is slow over 4 years old. The service life can reach 10 year.

Scapharca subcrenata can be harvested almost all year except in cold and hot summer. Trawls mainly used by motor fishing boats. However, if trawling back and forth for a long time, the beach sediment components in the distribution area will be seriously damaged, thus affecting the attachment and life of Scapharca subcrenata. The artificial propagation of Scapharca subcrenata has also begun.

Scapharca subcrenata can be eaten fresh after being cooked, and can also be dried. Shells can be used as raw materials for calcium carbide and cement, and can also be used as feed for poultry and livestock after crushing.