Clam is called Clam philippinarum, and its Chinese name is Clam philippinarum. The south of China is usually called Gehua, Liaoning is called Killer, and Shandong is called Gala. The Latin scientific name Ruditapes philippinarum or tapes philippinarum or Venerupis philippinarum is named by Adams et Reeve, and the English name 1850 is the classification of shellfish, molluscs, bivalves, clams and clams in the family short necked clam. The shell ligament of the Philippine clam is outside and located at the back. There are three main teeth and front teeth. Musculus bicuspidatus The sleeve bay is triangular or round or lacking. Shells are small, thin and oval. The top of the shell is slightly protruding, and the rear edge is slightly bent forward. The radial ribs are thin and thick before and after, and interweave with concentric growth rings to form a cloth pattern. The color and pattern of the shell surface vary greatly, with spots or patterns composed of brown, dark brown, dense brown or reddish brown. The inner surface of the shell is light gray or flesh red, and there are 2 ~ 3 light-colored bands from the top of the shell to the ventral surface. Habitual environment (1) Habitual environment Clam philippinarum mostly lives in the inner bay with less wind and waves, and there is a proper amount of fresh water injected in the middle and low tide areas, but occasionally coastal islands with high salinity and several meters deep subtidal zones are found; Sandy mudflats with a sediment concentration of 70% ~ 80% have the largest number. In mudflats with less sand content and sandy or gravel areas with less mud content, although there are some, the number is very small. (2) Lifestyle The Philippine clam lives in caves and digs sand and soil with developed axe feet. At high tide, it rises to the surface of the beach and extends out of the water pipe for breathing, feeding and excretion. After the dry tide or when encountering external stimulation, the double shells are closed tightly, or the telescopic activities of the feet retreat into the bottom of the cave, leaving two holes formed by the close proximity of the inlet and outlet pipes on the beach surface. The digging depth of Ruditapes philippinarum varies with individual size, sediment composition and seasonal changes. In the season when the individual is small, the bottom is soft or the water temperature is high, the cave is shallow; But if the individual is large, the bottom material is hard or in cold winter, it will dive deeper. But in general, the depth of the cave is about 3 ~ 15 cm. (3) Requirements for water quality 1. Water temperature: Clam philippinarum belongs to wide-temperature shellfish. In the natural sea area, the water temperature is in the range of 0 ~ 36℃, which can be adapted. When the water temperature is 5 ~ 35℃, the growth is normal, and it grows fastest at 18 ~ 30℃. The upper limit of suitable temperature for Meretrix meretrix is 43℃, and when the water temperature rises to 44℃, the mortality rate reaches 50%. When the water temperature rises to 45℃, all die; When the water temperature drops to 0℃, gill cilia stop moving and feeding stops; When the water temperature dropped to -2 ~ 3℃, the mortality rate reached 10% after three weeks. 2. Salinity: Ruditapes philippinarum also has strong adaptability to the change of seawater specific gravity. Life is normal when the specific gravity is 1.004 ~ 1.027, and it grows best when the specific gravity is1.015 ~1.020. In the inner bay culture area near the estuary without flood dike, a large number of Clam philippinarum died due to flash floods, not only because the proportion of seawater dropped sharply, but also because the flood brought a lot of sediment, which made the seawater turbid for a long time and affected the breathing and feeding of Clam philippinarum. 3. Dissolved oxygen: Ruditapes philippinarum can live normally in seawater with dissolved oxygen of 1 mg/L, so the dissolved oxygen content in normal seawater can meet the life needs of Ruditapes philippinarum. However, if the seawater is seriously polluted and the dissolved oxygen content continues to be lower than 0.5 mg/L 10 day, it will lead to the death of Ruditapes philippinarum. 4. Drought tolerance: Meretrix meretrix living in intertidal zone has strong drought tolerance, and the drying time is related to the individual size, temperature and ventilation of Ruditapes philippinarum.