Bivalves: Bivalvia

Clams, mussels, oysters, and scallops are raised commercially in the ocean for food. Oysters are sources of natural pearls and mother-of-pearl shell. For more than fifty years, cultured pearls have increased in both quantity and quality through advanced techniques in oyster culturing perfected by the Japanese.

Some bivalves are considered pests. They may concentrate bacteria, viruses, harmful chemicals and other pollutants in their bodies and can cause sickness and spread disease when eaten by humans. Shipworms burrow into and damage or destroy wooden structures, such as boats and piers. In the United States, introduced freshwater zebra mussels clog pipes of water treatment plants and irrigation systems, which cost millions to repair.