Responses of an aquatic isopod and amphipod to chemical alarm cues from damaged conspecifics

Abstract

Alarm cues are produced by an organism when injury occurs, and serve to signal danger when detected by conspecifics or to attract other predators that may disrupt the predation event. We exposed aquatic isopods (Caecidotea intermedius) and amphipods (Crangonyx setodactylus) to chemical stimuli from macerated conspecifics to test for the presence of alarm cues in these taxa. Three variables were examined during this experiment: time spent moving, time in refuge, and time in open. Despite previous evidence for the presence of alarm cues in both taxa, we found that only amphipods responded to alarm cues by decreasing overall movement. Isopods did not display any differences in behavior following exposure to alarm cues, which may be due to degradation of the active compounds in the alarm cues due to preparation and not the absence of these cues in general.