Intertidal Invertebrates of the Monterey Bay Area, California

Compiled & photographed by Gary McDonald, Long Marine Laboratory, University of California, Santa Cruz
Crassadoma gigantea (Gray, 1838)
Giant Rock-scallop
Mollusca: Bivalvia: Pteriomorphia: Ostreoida: Pectinina: Pectinoidea: Pectinidae
Geographic Range: Queen Charlotte Islands, British Columbia, Canada to Punta Abreojos, Baja California, Mexico. Synonyms: Hinnites giganteus, Hinnites multirugosus.
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Crassadoma_gigantea_slide_002.jpg
Monterey Bay, CA; 1982.

Description: Upper valve with imbricated radial ribs, often eroded in larger adults. Hinge purple on interior of shell. Mantle orange, with numerous small, blue eyes.

Size: Up to about 150mm diameter in the intertidal, up to 250mm in the subtidal.

Notes: Juveniles up to about 45mm are free-living and capable of swimming. Adults attach to substrate by the right valve, often becoming deformed to match the substrate.
Crassadoma_gigantea_slide_001.jpg
Monterey Bay, CA; 1982.		 Crassadoma_gigantea_0007.jpg
Carmel Pt., Monterey Co., CA; 23 Nov 2007; ~15mm. Free-living juvenile.

Crassadoma_gigantea_0010.jpg
Davenport Landing, Santa Cruz Co., CA; 24 Mar 2010; 105mm width of shell. View of hinge end of right (lower) valve, showing scallop shape of shell (22mm width) when the animal settled, and also the purple color of the hinge area.

  

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