Particle size selectivity and resource partitioning in five species of Thalassinidea (Crustacea: Decapoda)

Abstract

Particle selectivity was examined in Calocaris macandreae, Callianassa subterranea, Jaxea nocturna, Upogebia deltaura and U. stellata by comparing the inorganic particle size range within the gut with that from their respective environments. C. subterranea and C. macandreae are both deposit feeders, whilst J. nocturna is a re- suspension feeder, i.e. this shrimp flicks up deposited material ahead of the mouthparts and suspension feeds. U. deltaura and U. stellata are both predominantly suspension feeders. Particle size selectivity was not observed for either C. macandreae or J. nocturna. When the particle size range of the sediment taken from the upogebiid site was compared with that of the gut, particle selectivity was observed for both species. When particle size distribution from the gut was compared to that of the water column, however, no such evidence of particle selectivity was noted. For C. subterranea, no evidence of particle selectivity was observed in the specimens taken from a very fine muddy sediment. However, those taken from a sandier site showed clear evidence of particle selectivity. Interspecific and intraspecific particle size selection is discussed in relation to resource partitioning.