Abstract
Cementation and related shell structure in oysters (Expanded Abstract)
Yamaguchi, Keiko
Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen Band 190 Heft 2-3 (1993), p. 347 - 348
published: Dec 22, 1993
DOI: 10.1127/njgpa/190/1993/347
ArtNo. ESP155019002012, Price: 29.00 €
Abstract
Cementation is an adaptation that enables epibionts to fasten themselves to alien substrates. Shell structures of oysters have been described by several authors and are well known, but few studies have compared the cemented to the non-cemented part. This paper deals with the shell structure of the cemented part and the behaviour of the mantle margin during cementation, and examines cementation in oysters in order to understand how the cementing habit evolved. A significant structure named ’ridge-and-furrow structure’ occurs in the outermost shell layer in the cemented part of oysters. This structure was observed with the scanning electron microscope on adults of Crassostrea gigas, Saccostrea mordax and S. kegaki. The ridge-and-furrow structure is explained as a modification of the prismatic structure at sites of cementation. It consists of calcified ridges that are only a few microns wide and separated by narrow furrows. These ridges are arranged parallel to growth direction; the furrows between them become ultimately filled with shell material. The thickness of the ridge-and-furrow layer varies from 3-40 𝜇m depending on the topography of the substrate, on which it fills minute irregularities and hollows, thus allowing the shell to fit closely to the substrate. The organic matrix of this layer is continuous with the periostracum which acts as an initial adhesive. Laterally, the ridge-and-furrow structure grades into the prismatic structure, which forms the outermost layer in non-cemented parts of the shell.
Keywords
shell structure;oyster