Differential chemosensory feeding behaviour by three co-occurring mysids (Crustacea, Mysidacea) from southeastern Tasmania

Three mysid species showed differences in chemosensory feeding as judged from stereotyped food capturing responses to dissolved mixtures of feeding stimulant (either betaine–HCl or glycine) and suppressant (ammonium). The strongest responses were to 50:50 mixtures of both betaine–ammonium and glycine–ammonium solutions. In general, the response curve to the different mixtures tested was bell-shaped. Anisomysis mixta australis only showed the normal curve in response to the glycine–ammonium mixture. The platykurtic curve for Tenagomysis tasmaniae suggests a less optimal response to the betaine–HCl–ammonium solution. Paramesopodopsis rufa reacted more strongly to the betaine–ammonium than to the glycine–ammonium solutions, and more individuals of this species responded to both solutions than the other two species. It is suggested that these contrasting chemosensitivities of the three coexisting mysid species serve as a means of partitioning the feeding niche.