Video Analysis and Documentation of Eusocial Behavior in Commensal Amphipod Crustaceans

Video Analysis and Documentation of Eusocial Behavior in Commensal Amphipod Crustaceans

Eusociality is a term used in reference to the highest level of social organization in a hierarchical classification of populations and is typically associated with terrestrial invertebrates such as ants and bees. A species is typically deemed to have eusocial organization when it exhibits several complex social behaviors including cooperative care of young, nest guarding, and reproductive division of labor. Recently, scientists such as Emmet Duffy have documented eusociaity in marine crustaceans like the snapping shrimp, Synalpheus filidigitus. It is known that Gammeridian Amphipods have a social structure, but a determination as to whether or not their behavior is eusocial, sensu-stricto, remains to be determined. Specimens of Gammeridian Amphipods residing commensally within transparent tunicates, Ecteinascidia turbinata, were collected in situ from the Florida Keys. The amphipods were filmed within in the tunicates in microaquaria by special video cameras to record and document all behaviors, interactions, and any recognizable fixed actions responses for later analysis and classification. The resulting behavior profile revealed that the commensal amphipod under study, Anamixis cavitura Thomas, 1997, exhibits several complex behaviors and fixed action responses as well as recognition of "kin". The documented behavior profiles provide a strong basis for further investigation into possible mechanisms of eusocial structure in these amphipods.