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Advisor(s)
Abstract(s)
The ontogenetic development of acoustic communication has so far only been investigated in one fish species. In order to
determine whether detectability of conspecific sounds changes during growth in a species with limited hearing abilities
(generalist), we investigated the development of auditory sensitivity and agonistic vocalizations in the Lusitanian toadfish
Halobatrachus didactylus. Agonistic grunts were recorded, their sound pressure levels determined, and auditory sensitivities
measured in five different size groups ranging from 3 to 32·cm standard length. Hearing thresholds were obtained using the
auditory evoked potentials (AEP) recording technique. Dominant frequency, sound duration and number of pulses decreased,
whereas pulse period and sound level increased with increasing fish size. The best hearing was below 300·Hz in all groups. Lower
hearing sensitivity was found in the smallest juveniles at 100·Hz as well as at higher frequencies (800 and 1000·Hz). Comparisons
between audiograms and sound spectra within the same-sized fish revealed that smaller juveniles would be barely able to detect
agonistic grunts, while these vocalizations were clearly perceived by larger fish. In the latter, the main energy of sounds was
found at the most sensitive frequencies. This study demonstrates that acoustic communication in the Lusitanian toadfish might
be absent in early developmental stages and seems to start when juveniles are able to generate grunts of higher sound level and
lower dominant frequency.
Description
Keywords
Ontogeny Sound spectra Hearing Auditory evoked potential Acoustic communication Halobatrachus didactylus
Citation
Journal of Experimental Biology, 211, 502-509