1, different definitions
Many people say that oysters are oysters, which is actually a very broad statement. Oysters are widely distributed in China, from south to north, and from Yalu River in Hainan. Therefore, there are more than 30 kinds of oysters with different latitudes and different growth environments in the world, while there are more than 20 kinds of oysters with economic value in China, and oysters are a better one among the more than 30 kinds of oysters, so it is a big mistake to say that oysters are oysters.
2, the growth environment is different
Oysters are mainly grown or farmed at the intersection of rivers and the sea. Due to the limitation of growing environment, the number is very small. In recent years, with the increase of market demand, oysters have been farmed in a large area, but unfortunately, the growth cycle of oysters is long, usually in 2~3 years, so the price is expensive, while oysters are generally born on rocks by the sea, which has low environmental requirements, high yield, large quantity, short growth cycle and a little expensive.
Morphological characteristics of oysters
Oysters, except cryptosporidium, are attached to hard objects, such as rocks, stones, bamboo and wood. Use their left shells or early left shells. The shape of the shell varies greatly with the habitat environment and substrate. The left and right shells of some species are basically symmetrical, but in general, the right shell is flat and the left shell is sunken, and the left shell is even several times larger than the right shell. The outer layer is the stratum corneum, which is easy to fall off, and some individuals have no this layer.
Most species in prismatic layer form scales on the surface, and the density of scales varies greatly among different species. Some species roll up scales to form tubular spines of various sizes, such as hyoid spines. The nacre is usually milky white, green or brown and shiny. This layer participates in the formation of some special structures of shells, such as cavities in shells. The surface of shells is generally white or grayish white with black or purple-brown stripes.