Behavioral responses of a herbivorous calanoid copepod to the presence of other zooplankton

Abstract
Swimming behavior of the herbivorous calanoid copepod Diaptomus minutus consists of periods of rest interrupted by short jumps. Jumping frequency decreased in the presence of predatory copepods and increased in the presence of the herbivorous Daphnia pulex, a potential competitor. Because D. minutus is detected by vibration-sensitive predators when it jumps, its response in the presence of predators may be a prey defense mechanism. Since feeding by D. minutus takes place during the rest period and is interrupted by jumps, the response to the presence of D. pulex may indicate interference competition. The results demonstrate the behavioral flexibility of zooplanktonic organisms.