Geodock (Panope generosa: Bivalvia) Age as Determined by Internal Growth Lines in the Shell

Abstract
Geoduck (Panope generosa) age was determined by counting internal growth lines in the hinge plates of the shells. Several experiments substantiated the hypothesis that one growth line is deposited every year. Growth line deposition was found to occur during the winter.Key words: age, geoducks, Bivalvia, growth lines