Sound production mechanism in triggerfish (Balistidae): a synapomorphy

The ability to produce sounds for acoustic communication is known in different Balistidae species but the eventual synapomorphic aspect of the mechanism remains to be shown. In Rhinecanthus aculeatus, sounds result from alternate sweeping movements of the right and left pectoral fins, which push a system of three scutes against the swim bladder wall. In this study, we made a comparison between the sounds produced by this species and two additional ones (Balistapus undulatus and Rhinecanthus rectangulus) using hand held specimens to provide a description of the sound mechanism in B. undulatus. Results highlighted that the sound production mechanism is similar in the three species. According to recent phylogenetic data and shared morphological features, it means this mechanism could be common to the majority of the family members and that all Balistidae species could be all able of sound production using pectoral fins.