Significance to humans

Many kinds of bivalves, especially clams, cockles, mussels, oysters, and scallops, have served as important food sources for fish, vertebrates, other invertebrates, and humans. Aboriginal populations of many cultures have left evidence of eating bivalves in their kitchen middens (mounds or deposits of refuse from meals). Recent practices rely both on harvesting wild populations and on aquaculture in either open or closed aquatic systems. Members of the marine Pteriidae and freshwater Unionoidea have been sources of natural pearls and mother-of-pearl shell for centuries. Since the 1950s, cultured pearls have increased the quantity and quality of this biological gem through aquaculture and husbandry. The Japanese perfected the process of culturing pearls using pearl oysters of the species Pinctada fu-cata (Gould, 1850).

Bivalves have also had negative impacts on human activities. Because most bivalves are filter feeders, they are frequent vectors of human disease related to the concentration of bacteria, viruses, pesticides, industrial wastes, toxic metals, and petroleum derivatives from the water column. Shipworms (Tere-dinidae) have a long historical record of bioerosion of such human-made wooden structures as ships and docks. Species introduced in freshwaters of the United States, such as the bio-fouling zebra mussel Dreissena, have required millions of dollars to repair clogged water treatment plants and irrigation systems. Damage caused by such species to the environment, in terms of altered habitat and impact on native species, is irreversible; their spread has been largely unstoppable.

1. Eastern American oyster (Crassostrea virginica); 2. Queen scallop (Chlamys opercularis); 3. Yo-yo clam (Divariscintilla yoyo); 4. Common blue mussel (Mytilus edulis); 5. European pearly mussel (Margaritifera margaritifera); 6. Noble pen shell (Pinna nobilis); 7. Black-lipped pearl oyster (Pinctada margaritifera); 8. P. margaritifera internal view. (Illustration by Barbara Duperron)

1. Zebra mussel {Dreissena polymorpha); 2. Shipworm {Teredo navalis); S. Giant vent clam {Calyptogena magnifica); 4. Giant clam {Tridacna gi-gas); 5. Northern quahog {Mercenaria mercenaria); B. Watering pot shell {Brechites vaginiferus); l. Coquina clam {Donax variabilis); B. Coquina clam color morph 1; 9. Coquina clam color morph 2. {Illustration by Barbara Duperron)

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