SEROTONIN AND AGGRESSIVE MOTIVATION IN CRUSTACEANS - ALTERING THE DECISION TO RETREAT

In crustaceans, as in most animal species, the amine serotonin has bee n suggested to serve important roles in aggression, Here we show that injection of serotonin into the hemolymph of subordinate, freely movin g animals results in a renewed willingness of these animals to engage the dominants in further agonistic encounters, By multivariate statist ical analysis, we demonstrate that this reversal results principally f rom a reduction in the likelihood of retreat and an increase in the du ration of fighting, Serotonin infusion does not alter other aspects of fighting behavior, including which animal initiates an encounter, how quickly fighting escalates, or which animal eventually retreats, Prel iminary studies suggest that serotonin uptake plays an important role in this behavioral reversal.