Attachment of mature oysters (Saccostrea cucullata) to natural substrata

It has been suggested that mature oysters attach to their natural substrata by means of a combination of a modification of the prismatic outer-shell layer formed within the periostracum and a ''pressing'' action of the mantle (Yamaguchi 1994). However, marine surfaces are seldom smooth enough to allow adhesion without the addition of a fluid adhesive to allow electromagnetic interactions to hold the two bodies together. An electron microscope study of the attachment of the oyster Saccostrea cucullata to its natural substrata has confirmed the presence of a crystalline calcareous cement. The cement shows a range of spherulitic and irregular blocky textures that are reminiscent of diagenetic cement fabrics. Their form suggests that the cement crystallises from a calcium-carbonate-saturated liquor trapped between the underside of the shell and the substratum, with crystallites nucleating on all bounding surfaces of the void.