305
the thresholds decrease during ontogeny. Further studies need to be performed on
other cartilaginous fi sh to determine whether these results are representative of
hearing changes during development within this group of fi shes.
3.1.2 Teleostomi/Osteichthyes (Bony Fishes)
Clupeiformes
Within this order that includes several species with high commercial value, such as
herrings ( Clupea sp.), sardines ( Dussumieria sp., Escualosa sp. Sardina sp.,
Sardinella sp., and Sardinops sp.), shads ( Alosa sp.), and anchovies (over 15 species
with the most common being Anchoa sp., Thryssa sp., Stolephorus sp. and Coilia
sp.), very little is known on development of their hearing capabilities. Many species
that belong to this order are capable of ultra sound detection and understanding how
their auditory sense is adapted throughout ontogeny would certainly provide valuable information for the fi sheries industry and conservation.
In one of only two studies that have examined the development of hearing in
fi shes from this order, Blaxtey and Batty ( 1985 ) used a behavioral technique that
examined the development of startle responses evoked by auditory stimuli in the
larvae herring ( Clupea harengus ). These researchers found that the acoustic startle
response (i.e., the Mauthner mediated C-start escape response) to auditory stimuli
in herring larvae appeared after hatching. Herring larvae were observed to respond
to sound at 22–36 mm TL, while only responding to touch stimuli during earlier
stages of development at 10–12 mm TL.
In a second study, Higgs et al. ( 2004 ) conducted an ontogenetic physiological
study to evaluate the onset of ultrasound detection in the American shad, Alosa
sapidissima . According to the authors, once the developing shad was capable of
detecting sounds, the auditory sensitivity as measured using the AEP technique was
not observed to change with age/size. No improvements in sensitivity were registered with age/size, namely from larvae of 30–34 mm TL to adults greater than
100 mm TL over a frequency range of 0.1–90 kHz (Fig. 4 ). According to the authors,
the onset of ultrasound detection was coincident with the early development and
specialization of the utricle.
Cypriniformes
This order contains the Ostariophysian fi shes that possess accessory morphological
hearing structures (i.e., Weberian ossicles), which couple the inner ear to the anterior
part of the swim bladder that enable the fi sh to detect sound pressure stimuli.
The zebrafi sh ( Danio rerio ), a well-studied model, belongs to this taxon. This
species has become a signifi cant biomedical research model for investigating
human hearing and vestibular disorders as it combines genetics, embryology, and
excellent in vivo visualization all in a single organism (Whitfi eld et al. 2002 ; Lu and
Development of Structure and Sensitivity of the Fish Inner Ear
the thresholds decrease during ontogeny. Further studies need to be performed on
other cartilaginous fi sh to determine whether these results are representative of
hearing changes during development within this group of fi shes.
3.1.2 Teleostomi/Osteichthyes (Bony Fishes)
Clupeiformes
Within this order that includes several species with high commercial value, such as
herrings ( Clupea sp.), sardines ( Dussumieria sp., Escualosa sp. Sardina sp.,
Sardinella sp., and Sardinops sp.), shads ( Alosa sp.), and anchovies (over 15 species
with the most common being Anchoa sp., Thryssa sp., Stolephorus sp. and Coilia
sp.), very little is known on development of their hearing capabilities. Many species
that belong to this order are capable of ultra sound detection and understanding how
their auditory sense is adapted throughout ontogeny would certainly provide valuable information for the fi sheries industry and conservation.
In one of only two studies that have examined the development of hearing in
fi shes from this order, Blaxtey and Batty ( 1985 ) used a behavioral technique that
examined the development of startle responses evoked by auditory stimuli in the
larvae herring ( Clupea harengus ). These researchers found that the acoustic startle
response (i.e., the Mauthner mediated C-start escape response) to auditory stimuli
in herring larvae appeared after hatching. Herring larvae were observed to respond
to sound at 22–36 mm TL, while only responding to touch stimuli during earlier
stages of development at 10–12 mm TL.
In a second study, Higgs et al. ( 2004 ) conducted an ontogenetic physiological
study to evaluate the onset of ultrasound detection in the American shad, Alosa
sapidissima . According to the authors, once the developing shad was capable of
detecting sounds, the auditory sensitivity as measured using the AEP technique was
not observed to change with age/size. No improvements in sensitivity were registered with age/size, namely from larvae of 30–34 mm TL to adults greater than
100 mm TL over a frequency range of 0.1–90 kHz (Fig. 4 ). According to the authors,
the onset of ultrasound detection was coincident with the early development and
specialization of the utricle.
Cypriniformes
This order contains the Ostariophysian fi shes that possess accessory morphological
hearing structures (i.e., Weberian ossicles), which couple the inner ear to the anterior
part of the swim bladder that enable the fi sh to detect sound pressure stimuli.
The zebrafi sh ( Danio rerio ), a well-studied model, belongs to this taxon. This
species has become a signifi cant biomedical research model for investigating
human hearing and vestibular disorders as it combines genetics, embryology, and
excellent in vivo visualization all in a single organism (Whitfi eld et al. 2002 ; Lu and
Development of Structure and Sensitivity of the Fish Inner Ear