File:American malacological bulletin (1987) (18130058746).jpg

Title: American malacological bulletin
Identifier: americanmal4519861987amer (find matches)
Year: 1983 (1980s)
Authors: American Malacological Union
Subjects: Mollusks; Mollusks
Publisher: (Hattiesburg, Miss. ?) : (American Malacological Union)
Contributing Library: Smithsonian Libraries
Digitizing Sponsor: Biodiversity Heritage Library

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174 AMER. MALAC. BULL. 5(2) (1987)
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Plate 1. Central line figure represents right valve of Geukensia demissa granosissima (internal shell surface with retractor scars omitted) sur- rounded by micrographs of corresponding shell microstructure (45° angle view of fractures with internal shell surfaces towards the top). Horizontal field width of micrographs = 16 ^m. A. Nacre towards shell center (l2). B. Homogeneous (s.s.) just inside pallial line (h). C. Short prisms composing pallial line (P). D. Tall prisms of adductor myostracum (A). E. Nacre between pallial line and outermost rim of shell (0). Fig. E) again makes up the internal shell surface. The inter- nal shell surface microstructure of the outermost rim (i.e. peripheral edge), however, can also be prismatic, blocky prismatic or homogeneous (s.s.). Variation of internal shell surface microstructure in the outermost rim can be a reflec- toin of intermediate steps in the production of typically multiphasic outer shell layers. We predicted that baseline and experimental emerged mussels would have similar internal shell microstructure unless the emerged mussels were "impinged" by the environ- ment (over the one month duration of the experiment) or in- fluenced by a cage effect. Indeed, these two groups were similar in internal shell structure with minor exceptions. Emerged mussels lacked the well formed nacre (mature tablets and growing nuclei) that were found in isolated pockets inside and outside the pallial line of baseline mussels. For the comparative study of internal shell surface microstructures of emerged verus submerged mussels, on- ly mussels of similar lengths (about 50 mm) were used. The main difference between emerged and submerged mussels in 1984 (limited sample) was in the posterior region of the shell outside the pallial line (Plate 2, Figs. A-B). Sizes and shapes of tablets in submerged mussels (Plate 2, Fig. A) were different from those of emerged mussels (Plate 2, Fig. B). Tablets of the former were elongated along one axis. The 1985 transplantation experiment yielded greater internal shell surface microstructural differences between emerged and submerged mussels (Table 1). Relevant results presented in table 1 were based on examination of 10 valves of 10 individuals for each of the emerged and submerged

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