title: A novel hearing specialization in the New Zealand bigeye, Pempheris adspersa.
abstract: The New Zealand bigeye, Pempheris adspersa, is a nocturnal planktivore and has recently been found to be an active sound producer. The rostral end of the swim bladder lies adjacent to Baudelot's ligament which spans between the bulla and the cleithrum bone of the pectoral girdle. The aim of this study was to use the auditory evoked potential technique to physiologically test the possibility that this structure provides an enhanced sensitivity to sound pressure in the bigeye. At 100 Hz, bigeye had hearing sensitivity similar to that of goldfish (species with a mechanical connection between the swim bladder and the inner ear mediated by the Weberian ossicles) and were much more sensitive than other teleosts without ancillary hearing structures. Severing Baudelot's ligament bilaterally resulted in a marked decrease in hearing sensitivity, as did swim bladder puncture or lateral line blockage. These results show that bigeye have an enhanced sensitivity to sound pressure and provide experimental evidence that the functional basis of this sensitivity represents a novel hearing specialization in fish involving the swim bladder, Baudelot's ligament and the lateral line.
authors.affiliation: Leigh Marine Laboratory, University of Auckland, Warkworth 0941, New Zealand. c.radford@auckland.ac.nz
authors.forename: C A
authors.initials: CA
authors.lastname: Radford
authors.forename: J C
authors.initials: JC
authors.lastname: Montgomery
authors.forename: P
authors.initials: P
authors.lastname: Caiger
authors.forename: P
authors.initials: P
authors.lastname: Johnston
authors.forename: J
authors.initials: J
authors.lastname: Lu
authors.forename: D M
authors.initials: DM
authors.lastname: Higgs
mesh_terms: D000400:Air Sacs / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000502:physiology*; D000818:Animals; D001307:Auditory Perception; D005072:Evoked Potentials, Auditory; D006309:Hearing; D008279:Magnetic Resonance Imaging; D009520:New Zealand; D010473:Perciformes / Q000033:anatomy & histology / Q000502:physiology*; D011312:Pressure; D013016:Sound; D055114:X-Ray Microtomography
keywords: ancillary hearing structures; auditory evoked potentials; fish hearing