311
Fuiman et al. ( 1999 ) used acoustic startle responses to investigate hearing in the
sciaenid Sciaenops ocellatus (red drum) and observed an increase in sensitivity to
acoustic stimuli, as well as to visual stimuli, throughout ontogeny (mostly in early
larval stages with less than 8 mm TL). Several variables, such as response magnitude, frequency, duration, speed, and distance (to the auditory stimulus source)
increased considerably during early development.
Among the family Osphronemidae, the croaking gourami ( Trichopsis vittata ) has
been investigated by Wysocki and Ladich ( 2001 ), which revealed an increase in auditory sensitivity with size/age (from 20 mm to greater than 52 mm TL) for a frequency
range of 0.8–3 kHz. The authors also reported a shift in the most sensitive frequency
during development from 2.5 to 1.5 kHz (Fig. 4 ). According to Wysocki and Ladich
( 2001 ), such developmental changes in hearing sensitivity are most likely related to
morphological changes in the air-breathing apparatus of the suprabranchial chamber
that functions as an accessory hearing organ.
In contrast, the round goby ( Neogobius melanostomus ) belonging to the family
Gobidae has been investigated by Belanger et al. ( 2010 ) and showed similar AEP
thresholds with no changes in sensitivity during development across different size
stages ranging from 40 mm TL to greater than 120 mm TL. The authors of this
study suggest that the lack of size effects on auditory sensitivity is likely due to the
concurrent growth of both otolith (sulcus) area and auditory epithelium, which
results in maintaining hair cell density in the auditory macula during development.
In the spotfi n butterfl yfi sh ( Chaetodon ocellatus , family Chaetodontidae), Webb
et al. ( 2012 ) also reported the absence of ontogenetic changes in auditory sensitivity
to sound pressure in fi sh of 21–31 mm SL. However, the authors did report a signifi -
cantly higher sensitivity of larvae from this species compared to other similar-sized
larvae of other coral reef species that lack the swim bladder horns found in C. ocellatus . The absence of developmental hearing improvements in C. ocellatus may be
due to the fact that the swim bladder horns (accessory morphological hearing structures) are established earlier in development prior to a size of 21 mm SL.
More recently, Caiger et al. ( 2013 ) investigated the hearing abilities of hapuka
( Polyprion oxygeneios , family Polyprionidae) using AEP recordings and described
increases in both ontogenetic auditory sensitivity (up to 27 dB re 1 μPa) and in auditory bandwidth (from maximum of 800 up to 1000 Hz) within the fi rst year of
development (from 10 to 262 mm fork length). The authors suggested that the
development of rostral extensions of the swim bladder to the otic capsule may
explain the increased auditory sensitivity of this species during development.
3.2 Development of Auditory Capabilities for Social
Communication
Communication requires both a sender and receiver, thus one must analyze both the
development of auditory sensitivity and sound production when investigating how
acoustic communication develops in fi shes. Only three non-related species have
Development of Structure and Sensitivity of the Fish Inner Ear
Fuiman et al. ( 1999 ) used acoustic startle responses to investigate hearing in the
sciaenid Sciaenops ocellatus (red drum) and observed an increase in sensitivity to
acoustic stimuli, as well as to visual stimuli, throughout ontogeny (mostly in early
larval stages with less than 8 mm TL). Several variables, such as response magnitude, frequency, duration, speed, and distance (to the auditory stimulus source)
increased considerably during early development.
Among the family Osphronemidae, the croaking gourami ( Trichopsis vittata ) has
been investigated by Wysocki and Ladich ( 2001 ), which revealed an increase in auditory sensitivity with size/age (from 20 mm to greater than 52 mm TL) for a frequency
range of 0.8–3 kHz. The authors also reported a shift in the most sensitive frequency
during development from 2.5 to 1.5 kHz (Fig. 4 ). According to Wysocki and Ladich
( 2001 ), such developmental changes in hearing sensitivity are most likely related to
morphological changes in the air-breathing apparatus of the suprabranchial chamber
that functions as an accessory hearing organ.
In contrast, the round goby ( Neogobius melanostomus ) belonging to the family
Gobidae has been investigated by Belanger et al. ( 2010 ) and showed similar AEP
thresholds with no changes in sensitivity during development across different size
stages ranging from 40 mm TL to greater than 120 mm TL. The authors of this
study suggest that the lack of size effects on auditory sensitivity is likely due to the
concurrent growth of both otolith (sulcus) area and auditory epithelium, which
results in maintaining hair cell density in the auditory macula during development.
In the spotfi n butterfl yfi sh ( Chaetodon ocellatus , family Chaetodontidae), Webb
et al. ( 2012 ) also reported the absence of ontogenetic changes in auditory sensitivity
to sound pressure in fi sh of 21–31 mm SL. However, the authors did report a signifi -
cantly higher sensitivity of larvae from this species compared to other similar-sized
larvae of other coral reef species that lack the swim bladder horns found in C. ocellatus . The absence of developmental hearing improvements in C. ocellatus may be
due to the fact that the swim bladder horns (accessory morphological hearing structures) are established earlier in development prior to a size of 21 mm SL.
More recently, Caiger et al. ( 2013 ) investigated the hearing abilities of hapuka
( Polyprion oxygeneios , family Polyprionidae) using AEP recordings and described
increases in both ontogenetic auditory sensitivity (up to 27 dB re 1 μPa) and in auditory bandwidth (from maximum of 800 up to 1000 Hz) within the fi rst year of
development (from 10 to 262 mm fork length). The authors suggested that the
development of rostral extensions of the swim bladder to the otic capsule may
explain the increased auditory sensitivity of this species during development.
3.2 Development of Auditory Capabilities for Social
Communication
Communication requires both a sender and receiver, thus one must analyze both the
development of auditory sensitivity and sound production when investigating how
acoustic communication develops in fi shes. Only three non-related species have
Development of Structure and Sensitivity of the Fish Inner Ear