Beyond Shells: The Giant Rock Scallop
The Giant Rock Scallop, Crassadoma gigantea, is another nice highlight from the cold-water touch pool at the Museum. The fact that many species of scallops can swim, relying on bursts of jet-propelled water, always comes up when we talk about the cool things mollusks do for a living. But Giant Rock Scallops are large scallops that don’t swim, spending instead their adult lives attached to hard surfaces such as rocks. Like their swimming relatives, Giant Rock Scallops have a large number of small eyes that help them detect approaching predators. They live in shallow waters off the West Coast of North America, where they spend their early lives as swimming larvae, then as free-living young scallops. By the time they reach about 45 mm (about 1.8 inch), they start cementing their bottom valves to rocks. From then on, they spend the rest of their lives on the same spot, camouflaged against the general landscape of the rocky shore, where they filter the water to gather micro-algae for food.