Calcium concentration inside the mantle cavity changes when

Calcium concentration inside the mantle cavity changes when the clam opens and closes.
• What happens to calcium concentration when the valves are closed? Open?
• Why does calcium concentration change when the valves are closed?

Solution

Under normal condition, when valves close, oxygen cannot enter to the mamle cavity. In this condition anaerobic respiration takes place due to which accumulation of succinic acid takes place inside the mantle cavity. To neutralize this succinic acid, dissolution of inner shell (valve, clamp) occurs. Due to dissolution of shell, release of calcium ion, CO₂ and hydrogen ion into the fluid of mental cavity occurs. Hence the calcium ion concentration increases during valve closing. When valve opens, aerobic respiration starts and the level of succinic acid decreases in mantle cavity, consequentlly the calcium ion deposition to the shell from mantle cavity starts again. Hence the calcium ion concentration decreases during valve opening.