Responses of the amphipod crustaceanGammarus palustris to waterborne secretions of conspecifics and congenerics.

A choice-test apparatus designed to mimic field conditions was employed to test for the presence of waterborne attractants in the amphipod crustaceanGammarus palustris. It was found that both males and females were attracted to secretions from all conspecifics, but not to the secretions of a sympatric congener. When given the choice of secretions from different types of conspecifics, males behaved differently than females. Males were attracted more often to receptive females' and females were attracted more often to males' secretions. In the field, then, it is likely that all conspecifics travel toward each other, then sort themselves into competent heterosexual couples. The results suggest that this apparatus can be employed in future studies to determine the chemical nature of these pheromones.