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Marine species

Rock Scallop

Crassadoma gigantea

The rock scallop (Crassadoma gigantea) is a large bivalve mollusk found along the Pacific coast of North America. Adults reach 15-25 cm in diameter and cement their lower valve permanently to rocky substrates, unlike their free-swimming relatives. When open, they reveal a vivid orange mantle edge lined with rows of tiny, iridescent blue-green eyes that detect shadows and movement, triggering the shell to snap shut when predators approach. The shell exterior becomes encrusted with coralline algae, sponges, and other organisms, providing camouflage. They inhabit rocky reefs, kelp forests, and boulder surfaces at depths of 2-80 meters, filter-feeding on plankton and organic particles. Their sedentary lifestyle and camouflaged exterior make them easy to overlook, but once spotted, the brilliant orange and blue eye display is stunning. They can live for over 50 years, and large specimens become permanent features of their reef environment.

Where to see Rock Scallop

Dive sites where Rock Scallop is recorded.

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