Oyster is the shell of Crassostrea gigas, Crassostrea gigas and Crassostrea Dalian. Oysters near the river and long oysters are distributed along the coast of China, and oysters in Dalian Bay are distributed along the northern coast of China 1. Oysters along the river have round, oval, triangular or slightly longer shells, which are firm and thick. The larger one is 100-242mm in length and 70- 150 mm in height, and the left shell is large and thick with attachments on the back. The right shell is slightly flat, and the surface ring has thin and flat scales, yellow-brown or deep purple. It is an individual of 1-2 years old, with thin and brittle scales and sometimes free edges. Individuals from 2 to several years old have flat scales, and sometimes the tail edge fluctuates slightly in water waves; Perennial scales are layered and very thick. The inner surface of the shell is white or gray-white, and the edge is often gray-purple, uneven, the hinge is toothless, and the ligament groove is long and wide, such as horn and purple-black ligament. The adductor muscle has a large scar, which is located at the back of the middle, pale yellow and irregular in shape, often changing with the shell shape, mostly oval or kidney-shaped. 2. Long oysters with long and thick shells. Generally, the shell length is 140-330mm, the height is 57- 1 15mm, and the ratio of length to height is about 3 times higher. The largest known oyster is 722 mm. The left shell is slightly concave, the attachment surface of the top of the shell is small, the right shell is flat as a cover, the dorsal and ventral edges are almost parallel, and the shell surface is lavender, grayish white or yellowish brown. Sparse scales are arranged in a ring shape from the top of the shell to the back edge, slightly wavy, with few layers and no obvious radial ribs. The inner surface of the shell is porcelain white, the ligament groove is long and wide, and the muscle scar of the closed shell is large, which is located at the back of the shell and is brown horseshoe-shaped. 3. The oyster in Dalian Bay has a slightly triangular shell and a thick shell. Generally, the shell is 55-63mm long and 95- 130mm wide, and the shell gradually widens from the top to the rear edge. The right shell is flat, such as the lid, and the scales at the top of the shell tend to heal and are thicker; Gradually, the scales at the belly edge become loose, undulating and wavy, without obvious radial ribs. The shell surface is light yellow with purple-brown markings, and the left shell is protruding. From the top, there are several thick radial ribs, and the scales on the ribs are thick and inclined. The shell is concave, white, with a small hinge and a long and deep ligament groove, which is in the shape of the Yangtze River Delta. The adductor scar is white or purplish, located at the back. Oyster salvage 4. Pacific oyster, with round or oval shell and thick shell, is generally 46- 122mm long and 58- 138mm high. The left shell is large and concave, and the top of the shell is an attachment surface, which is often irregular in shape. The scales at the top of the right shell heal smoothly, and gradually ring to the abdominal edge, thin and brittle, flaky, closely arranged in a strip shape, with many radial ribs, making the abdominal edge slightly wavy, and the shell surface is gray-blue mixed with purple-brown. The inside of the shell is white with a little pearl luster. There are often 1 rows of small teeth on both sides of the hinge, about 5-8. Ligament sulcus is short and triangular. The muscles with closed shells have large scars. Irish stone oysters have a strong taste. Take a sip of white wine after the entrance, and the fragrance of white wine will bring out the taste of oysters. I feel the thick smell of oysters around my teeth. Scottish scallop oysters first tasted salty sea water, but later the taste of the sea water faded and the skirt was slightly pinched. The fat surface of the tail is sticky. The western Pacific stone oyster is neutral in taste, sweet in meat and light in seawater. Seattle stone oysters are fragrant, refreshing and not fat. The sea water tastes weak. After eating, the aroma of oysters remains in the mouth. Eat oysters by the month: American oysters, Australian oysters: September 65438+ 1 October 65438+1October Irish oysters: early February 65438+Japanese oysters, French oysters: 65438+mid-February Figure: In counterclockwise order:1.