© Joseph Dougherty. All rights reserved.
Crassadoma gigantea (J.E. Gray, 1825)
Adults of Crassadoma gigantea have one valve (the right valve) fixed to a base, often a vertical rock face. This valve often becomes deformed to fit the contours of the rock. The left valve is roughly circular but irregular in outline, thick and heavy, with deep radial ribs. Every third or fourth rib is clad with blunt spines that overhang each other. These often get abraded and worn smooth as the scallop ages. There are flaps of shell known as auricles on either side of the straight hinge. The general color is brown with the inside of the shell being glossy white with a purple patch at the hinge and a large, central adductor muscle scar. Crassadoma gigantea grows to a diameter of 15 centimeters (5.9 in) in the intertidal zone and 25 centimeters (9.8 in) in the subtidal zone. Between the valves, the margin of the orange mantle can be seen, with a row of tiny blue eyes and a sparse fringe of short tentacles.
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From Old 35mm Slide Scans