CATDOLL : CATDOLL: How many species of shellfish are there in the world?

●There are 120,000 species of shellfish in the world, which is the second largest group of organisms in nature after insects.

● More than 2,000 species of shellfish live in the South China Sea, adding rich colors to Hainan’s marine culture

●It is not enough to learn about shellfish only from the dining table

When I first arrived in Hainan, I often ate a kind of fragrant and light winter melon and conch soup. After staying on the island for a long time, I learned that this soup is known as the best soup in Hainan. When I was suffering from indigestion, fatigue, and tiredness, I would cook a pot of this soup, and I would feel much more comfortable immediately after eating it. Many people began to know this marine life---shellfish from the dining table. However, knowing shellfish only from the dining table is too superficial. Shellfish is a very precious resource given to human beings by nature. There are about 120,000 species of shellfish in the world. There are traces of shellfish everywhere in rivers, streams, lakes, and oceans. It is the second largest group of organisms in nature after insects. The peculiar shapes, pleasing colors, and wonderful patterns show the gifts of nature's magic, which is amazing. In the long river of history, shellfish have reflected the evolution and progress of human society with their unique charm. Types of Shells Shells in the world can be roughly divided into two types: terrestrial and aquatic, of which aquatic marine shells account for more than 80% of the total. Marine shells are essentially mollusks, characterized by a soft and unsegmented body, consisting of five parts: head, foot, visceral sac, mantle and shell. Shells can be divided into five categories according to the shape and structure of their shells. Gastropods: including snails, conchs and periwinkles, which are spirally twisted; Bivalves: including clams, oysters and scallops, which are generally composed of two shells, in the shape of petals; Cephalopods: including squid, nautilus and octopus; Polyplacopods: This type of shell has up to 8 shell plates, forming a peculiar shape; Scaphopods: The top of the shell is forward, the membrane surface is curved, and it is shallowly hat-shaped. Among the five types of shells, gastropods and bivalves are the most, accounting for more than 80-90% of the total existing shells. The structure of shells. Typical shells have three layers. The outer layer is a textured layer called chitin, which is a hard protein. The middle layer is thicker and is called the prismatic layer or shell layer. The inner layer is a leaf-shaped aragonite structure, which is very shiny and is called the nacre layer. The outer and middle layers are secreted by the back edge of the outer membrane, while the inner layer is secreted by the entire surface of the mantle. Some shells do not have these three layers, such as clams and squids. The main component of shells is calcium carbonate, which accounts for 95% of the total composition. Other components include inorganic substances such as magnesium, iron, calcium phosphate, calcium sulfate and silicate, as well as a small amount of organic substances such as chitin. In Chinese, there are many names for shells. The most commonly used ones are shells, conchs, oysters, clams, etc.; others are chitons, abalones, giant clams, octopuses, cuttlefish, dugongs, mussels, snails, slugs, insects, clams, razor clams, squids, snails, etc., which can be said to be varied. There are more than 100,000 types of shellfish in terms of shape. Some are shaped like bamboo hats or hats, some are shaped like gyroscopes, cones, pagodas, and others are shaped like disks or spheres. The shellfish of different shapes also vary greatly in size. The rainbow pupa snail is as small as 0.03 mm long, and the largest shell of the giant clam is 1.8 meters long and weighs about 500 kilograms. The colors of shellfish include almost all natural colors, and their patterns are even more varied and amazing. Hainan's shellfish have a variety of vast marine environment. Hainan Island has excellent water quality, stable salinity, and moderate water temperature, which provides good living conditions for various mollusks to live and reproduce, forming Hainan's unique and rich shellfish resources. According to incomplete statistics, there are nearly 2,000 species of marine shellfish in Hainan waters, and some species are unique. Among them, abalone, horse hoof snails, mussels, mud clams, hairy clams, river clams, scallops, sun and moon shells, clams, etc. are edible. The abalone shells, turban shells (called mica stone in Chinese medicine), cone shell shells and meat, treasure shells, red snail shells and their shells and meat, lychee snail shells, mud clam shells, mussel shells, oyster shells, clam shells and meat, etc. can be used for medicinal purposes. The pearl oysters growing in the waters of Hainan are one of the precious shellfish. The main pearl oysters that produce seawater pearls are the Pinctada martensii, the Pinctada edulis (commonly known as the black butterfly shell), the Pinctada maxima (commonly known as the white butterfly shell), etc. Among them, the Pinctada maxima is the largest species, with a shell length of more than 30 cm, a solid and thick shell, a gray-yellow-brown radial rib on the shell surface, and a rich silver-white pearl layer inside the shell. It often inhabits the sea area with a depth of about 20 meters and is a unique species of Hainan Island. The pearls and shells of the pearl oysters, the luminous conch shells, the nautilus, the tiger-striped treasure, the conch, the crown snail, the hedge conch, the spotted conch, the cone snail, etc. can be used to make decorations and handicraft shell carvings. These handicrafts, which have been carefully or simply carved, convey a different kind of marine cultural atmosphere. Shells, known as natural and precious works of art, have also become treasures in the collection world. Many natural museums in the world have special shell museums, which have become a good place for people to watch. At present, the shell museum with the largest exhibition area and the most shell varieties in my country is the Shell Art Museum of Haikou Tropical Ocean World, which was built in June 2001. Its exhibition area is more than 700 square meters, and the original shell collection has more than 800 species. The museum also has a collection of world-famous shells. The Shell Museum in Yalong Bay, Sanya, is the first professional shell exhibition hall in my country. The museum has a rich variety of shell art and is a shopping paradise for shell crafts.

Shellfish belongs to the class Bivalvia (or Bivalvia) in the phylum Mollusca. They are named because they are generally covered with 1-2 shells. Many common oysters, mussels, clams, razor clams, etc. belong to this category. There are about 11,000 species in existence, of which 80% live in the ocean. my country has vast sea areas, with a mainland coastline of 18,000 km, and the coastlines of the mainland and islands are tortuous, forming many excellent harbors and tidal flats. The area of ​​tidal flats and shallow waters below 5 m in the Bohai Sea, the Yellow Sea, the East China Sea and the South China Sea is more than 14 million hectares. Among them, the shallow sea area is more than 12 million hectares, and the intertidal zone tidal flat area is more than 2 million hectares. The area is vast and the natural bait is abundant. There are many kinds of shellfish naturally distributed along the coast of my country, of which more than 40 species can be cultivated, and the source of seedlings is wide. The promotion of semi-artificial seed collection in natural sea areas, factory-based indoor artificial seedling cultivation, and artificial seedling cultivation in earthen ponds has provided rich seedling resources for the development of shellfish farming. Shellfish farming in my country has made great progress in the past 20 years. Shellfish farming has also occupied an increasingly large proportion in the marine aquaculture industry due to its small investment, high efficiency, labor saving and simple management technology, which can effectively utilize natural elimination to the greatest extent.