The trophic behaviour, stomach contents, and morphology of the feeding appendages, with emphasis on setae, of a species of Laomediidae, Axianassa australis (Crustacea: Decapoda: Thalassinidea), were investigated. This species is a deposit feeder. The 32 described setal types were clustered in four main categories: plumed, serrate, plumodenticulate and simple. By examining the setae and spatial position of the segments of the appendages, it is possible to infer that the main function of the 1st and 2nd pereiopods, the 3rd pair of maxillipeds, as well as the dactylus, propodus, carpus and merus of the 2nd maxilliped, is to brush particles. The ischium, basis and coxa of the 2nd maxilliped appear to be specialized for particle retention. For the remaining mouthparts, brushing is generally the main function of the basal endites, while the coxal endites retain particles. Patterns of morphological adaptations to feeding habits are proposed for the Thalassinidea based on a review of the literature. Setal diversity, ratio of plumodenticulate to serrate setal types and mandible morphology are linked to ecological adaptations to trophic modes. Conversely, the presence and degree of development of the crista dentata appear to be related to phylogenetic heritage rather than to feeding mechanisms. Stomach contents are also indicative of trophic modes used by the species; while the predominance of small particles can indicate either filter or deposit feeding, stomach contents with high quantities of large particles suggest deposit feeding as the exclusive trophic mechanism.