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Family Gryphaeidae - honeycomb oysters
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Order |
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Class |
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Bivalvia |
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No. of Genera in Ref. |
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No. of Species in Ref. |
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Environment |
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Fresh : No |
Brackish : No |
Marine : Yes |
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Remark |
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To about 30 cm. Marine (Ref. 94508). Shell solid, often irregularly shaped, more or less inequivalve, cemented to substrate by the left (lower) valve which is generally somewhat deeper and larger. Both valves convex and similarly sculptured, with large, irregular radial ribs provided with hollow tubular extensions, or right (upper) valve quite flat, with imbricating thin plates of horny material tending to protrude beyond the shell margin. Shell with a microscopic vesicular structure, easily seen under a lens on an eroded part of the shell or along peripheral area of the interior. Ligamental area with a shallow median groove. Hinge without teeth. Umbonal cavity generally very shallow. A single, large and rounded (posterior) adductor muscle scar, placed closer to the hinge than to the ventral margin. Pallial line without a sinus, obscure to absent. Internal periphery of the valves with a slight inframarginal fold or line. Internal margins with long, branched, sinuous chomata on either side of the ligamental area. Gills of eulamellibranchiate type. Pallial lobes free, with marginal tentacles. Suspension filter-feeding animals, living cemented to the substrate by the left valve, either in littoral and shallow subtidal levels, or in deeper waters. Sexes separate. Fertilization external, without an incubator stage, yielding free-swimming planktonic larvae. Though they are collected in many areas, Gryphaeidae are generally less prized than species of the related family Ostreidae (Ref. 348). |
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