Morphotype Related Dominance Hierarchies in Males of Macrobrachium Rosenbergii (Crustacea, Palaemonidae)

Agonistic interactions in groups of Macrobrachium rosenbergii males were investigated in the laboratory. Each of the ten replicate groups consisted of the three distinct male morphotypes of this species: two Blue Clawed (BC) males and two Orange Clawed (OC) males matched to size, and two, much smaller, Small Males (SM). Male prawns formed a linear dominance hierarchy in which BC males were dominant over OC males which, in turn, were dominant over SM. Stabilization of the hierarchy over a period of three days was evident from reduction in the number of agonistic interactions and their intensity with time. The three male morphotypes differed in the extent to which they were involved in agonistic interactions and the nature of these interactions.