page_title: Crassadoma
section_title: Description
hierarchical_section_title: Crassadoma / Description
caption_attribution_description: The giant Pacific rock scallop Crassedoma giganteum lives with one valve attached to the rock and the other free to open and close. A sponge covers the shell entirely.
context_page_description: Crassadoma is a genus of rock scallops, marine bivalve molluscs in the family Pectinidae. It is monotypic, the only species being Crassadoma gigantea, the rock scallop, giant rock scallop or purple-hinge rock scallop. Although the small juveniles are free-swimming, they soon become sessile, and are cemented to the substrate. These scallops occur in the eastern Pacific Ocean.
context_section_description: 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 colour 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 centimetres (5.9 in) in the intertidal zone and 25 centimetres (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.
caption: A rock scallop with a sponge covering its shell
exif: {"Image Make": "Canon", "Image Model": "Canon EOS DIGITAL REBEL", "Image Orientation": "Horizontal (normal)", "Image XResolution": "300", "Image YResolution": "300", "Image ResolutionUnit": "Pixels/Inch", "Image Software": "Adobe Photoshop Elements 2.0", "Image DateTime": "2006:09:22 12:38:41", "Image YCbCrPositioning": "Centered", "Image ExifOffset": "232", "Thumbnail Compression": "JPEG (old-style)", "Thumbnail XResolution": "72", "Thumbnail YResolution": "72", "Thumbnail ResolutionUnit": "Pixels/Inch", "Thumbnail JPEGInterchangeFormat": "1066", "Thumbnail JPEGInterchangeFormatLength": "6827", "EXIF ExposureTime": "1/125", "EXIF FNumber": "8", "EXIF ISOSpeedRatings": "100", "EXIF ExifVersion": "0221", "EXIF DateTimeOriginal": "2005:09:16 13:48:28", "EXIF DateTimeDigitized": "2005:09:16 13:48:28", "EXIF ComponentsConfiguration": "YCbCr", "EXIF CompressedBitsPerPixel": "3", "EXIF ShutterSpeedValue": "228255/32768", "EXIF ApertureValue": "6", "EXIF ExposureBiasValue": "0", "EXIF MaxApertureValue": "43317/16384", "EXIF MeteringMode": "Average", "EXIF Flash": "Flash did not fire", "EXIF FocalLength": "50", "EXIF FlashPixVersion": "0100", "EXIF ColorSpace": "Uncalibrated", "EXIF ExifImageWidth": "1200", "EXIF ExifImageLength": "800", "EXIF FocalPlaneXResolution": "768000/223", "EXIF FocalPlaneYResolution": "409600/119", "EXIF FocalPlaneResolutionUnit": "2", "EXIF SensingMethod": "One-chip color area", "EXIF FileSource": "Digital Camera", "EXIF CustomRendered": "Normal", "EXIF ExposureMode": "Manual Exposure", "EXIF WhiteBalance": "Auto", "EXIF SceneCaptureType": "Standard"}