Acoustico‐lateralis communication in coral reef butterflyfishes

Abstract

Butterflyfishes are conspicuous members of coral reefs and well known for their pairing behavior and visual displays during social interactions. Members of the genus Chaetodon have a unique arrangement of the anterior swim bladder horns that connect with the lateral line (the laterophysic connection) and also project towards the inner ear, but functions for this putative acoustico‐lateralis adaptation were not known. Field experiments demonstrate that the monogamous multiband butterflyfish, C. multicinctus, produces hydrodynamic pulses and sounds during territorial defense, and pulse trains that may be an alert call to the mate. In field choice tests, individuals could distinguish mates from nonmates and produced different calls to each, thus demonstrating the existence of mate recognition and context‐specific sound production. Laboratory experiments show that sound production differs among sexes, hydrodynamic pulses are of low frequency (<100 Hz), and sounds have peak energy from 100–500 Hz. Auditory evo...