blood clam

Latin scientific name

Scapharca subcrenata

another/alternative name

Clam, clam, blood clam

boundary

animal kingdom

door

Mollusca (Mollusca)

outline

Bivalvia (Bivalvia)

eye

Taxodonta (Taxodonta)

branch of academic or vocational study

Arcidae (Arcidae)

belong to

Scapharca

distribution area

China, Korea and the Japanese coast. China, Bohai Sea and the East China Sea are more offshore.

morphological character

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Common shells are 3 cm high, 4 cm long and 3 cm wide. The shell is thick and oval, usually the two shells are different in size, and the right shell is slightly smaller. The dorsal ends are slightly angular, the front end of the abdominal edge is round, and the back end is slightly extended. The top of the shell is protruding and curled inward, and the position is biased forward, and the distance between the top of the two shells is not far. There are about 35 radial ribs on the shell surface, and there are square knots on the ribs, which are like tiles. Growth line is very obvious on the ventral side. The shell is white and covered with brown fluffy shell. The shell is white, and the edge of the shell has teeth. The hinge is very narrow, straight and with fine teeth.

biological property

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The digestive organ consists of mouth, esophagus, stomach, intestine and anus. The main foods are diatoms and organic debris. The gonad is wrapped around the digestive gland (visceral mass). When the female is sexually mature, the gonad village is purple, while the male is yellow-white. The opening of the gonad hole is on the ventral surface of the posterior obturator muscle, and the left and right are 1 piece. Eggs (50-60 microns in diameter) are fertilized and hatched in seawater. Scapharca subcrenata, which lives in Liaodong Bay of Bohai Sea, mostly lays eggs from early July to early August. During the breeding period, there are 2-3 peaks of sperm egg discharge, with an interval of about half a month each time. Left-handed and right-handed individuals with a shell length of 4 cm can ovulate 2-3 million eggs at a time. The spawning water temperature is mostly between 25-27℃. The larvae float in seawater and enter D-shaped larvae in trochophore stage. At 150 μ m, the top of the shell begins to be obviously larger than the height of the shell and nearly oval. After the shell is 220 microns long, "eye point" appears, and it is about to enter the attached metamorphosis life. The whole floating period takes about 16- 17 days. After the larvae end their floating life, they attach themselves to sand, shells, seaweed and other solid objects with sufficient silk. Foot silk is banded and exists for life; After shedding, it has the ability to regenerate and attach. When the shell is as long as 1.2- 1.5 cm, it falls into the bottom of the sea and becomes a shallow-buried life, and it takes about 2-2.5 years to grow into a shell.

living environment

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Living in the mud and sand bottom with a water depth of more than 10 meters from the low tide line of the shallow sea in the inner bay, especially near the estuary where fresh water flows out, mostly 4-8 meters.

The separation of subcrena subcrenata larvae from the attachment base to the dormant life is mainly related to the water temperature and individual size. When the water temperature dropped to 19℃, 80% of the larvae with body length ≥4 5mm began to break away from the attachment base, and the time for them to live in seclusion was from mid-September to1early October of that year. The body length of 4 5mm basically does not leave the attachment base. The larvae of the same size grow 36% faster after hiding than on the attachment base. The optimum water temperature for the growth of young shellfish is 20 ~ 26℃, and the growth gradually slows down below 20℃, and basically stops growing and feeding at 7℃.