アコヤガイの幼生期・稚貝期における殻体の内部構造

概要

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The internal shell structure of Pinctada fucata martensii(DUNKER) in the larval and juvenile stages was examined by an electron micro-probe analyser(EPMA), a X-ray diffractometer and a scanning electron microscope. The shell in umbo larval stage is made of aragonitic crystallites. This result is different from WATABE'S inference (1956), that is the larval shell may be composed of calcite. Moreover, calcium is detected by EPMA in the shell of straight-hinge larva stage, but phosphorous is not. Then, it is probable that the larval shell is made of carbonate crystal, maybe aragonite. After metamorphism, the calcite crystal of a shell newly is formed in addition to aragonite formation. Next, the umbo larval shell is made of aggregation of small crystallites. They do not arrange regularly, but partly arrange right to an inner surface. The shell structure is different from one of juvenile and adult shells which is composed of an outer calcareous shell layer of prismatic structure and an inner calcareous shell layer of nacreous structure.
地学団体研究会の論文
1981-09-25