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Bivalves: Bivalvia

Behavior And Reproduction

Most bivalves stay in the same place for much of their lives, but others are able to move around. Burrowers move up and down through mud and sand by extending their foot. Then they expand the tip of their foot to anchor themselves and pull their shelled bodies up or down in the burrow. Others "swim" through the water by clapping their valves together.


The geoduck (gooey-duck) is the common name for the clam Panopea abrupta. It burrows in the sandy beaches along the North American shore of the Pacific Ocean from Alaska to California. The Nisqaully tribe of southern Puget Sound hunted and ate this clam and called it gweduc, which means "dig deep." The first European settlers in the region changed the name to gooeyduck or goeduck. In time, through countless misspellings, the bivalve became known as a geoduck.

Bivalves usually require both males and females to reproduce, although some species individuals either have the organs of both sexes or start out as males and later become females. Bivalve eggs and sperm are usually released into the water, where fertilization takes place. The eggs hatch into veligers (VEL-ih-jerz), or young, that live among and eat other plankton. Plankton is made up of microscopic plants and animals that drift about on ocean currents. Eventually, the veligers settle on rocks, wood, or the ocean bottom and begin to develop their valves.

Additional topics

Animal Life ResourceMollusks, Crustaceans, and Related SpeciesBivalves: Bivalvia - Physical Characteristics, Behavior And Reproduction, Bivalves And People, Conservation Status, Black-lipped Pearl Oyster (pinctada Margaritifera): Species Accounts - GEOGRAPHIC RANGE, HABITAT, DIET