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See detailFurther insight into the sound-producing mechanism of clownfishes: what structure is involved in sound radiation?
Colleye, Orphal ULg; Nakamura, Masaru; Frederich, Bruno ULg et al

in Journal of Experimental Biology (2012), 215

It was recently demonstrated that clownfishes produce aggressive sounds by snapping their jaw teeth. To date, only the onset of the sound has been studied, which raises the question, what structure is ... [more ▼]

It was recently demonstrated that clownfishes produce aggressive sounds by snapping their jaw teeth. To date, only the onset of the sound has been studied, which raises the question, what structure is involved in sound radiation? Here, a combination of different approaches has been used to determine the anatomical structure(s) responsible for the size-related variations observed in sound duration and frequency. Filling the swimbladder with physiological liquid specifically modified size-related acoustic features by inducing a significant decrease in pulse duration of approximately 3 ms and a significant increase in dominant frequency of approximately 105 Hz. However, testing the acoustics of the swimbladder by striking it with a piezoelectric impact hammer showed that this structure is a highly damped sound source prevented from prolonged vibrations. In contrast, the resonant properties of the rib cage seems to account for the size-related variations observed in acoustic features. For an equivalent strike on the rib cage, the duration and dominant frequency of induced sounds changed with fish size: sound duration and dominant frequency were positively and negatively correlated with fish size, respectively. Such relationships between sonic features and fish size are consistent with those observed in natural sounds emitted by fish. Therefore, the swimbladder itself does not act as a resonator; its wall just seems to be driven by the oscillations of the rib cage. This set of observations suggests the need for reassessment of the acoustic role of swimbladders in various fish species. [less ▲]

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See detailAgonistic sounds in the clownfish Amphiprion clarkii: implication of the swimbladder in the sound-producing mechanism
Colleye, Orphal ULg; Nakamura, Masaru; Parmentier, Eric ULg

Poster (2009)

Clownfishes are aggressive fishes that use sound production to defend their anemone territory. It has been shown that they produce agonistic sounds using a jaw teeth snapping. At present, this mechanism ... [more ▼]

Clownfishes are aggressive fishes that use sound production to defend their anemone territory. It has been shown that they produce agonistic sounds using a jaw teeth snapping. At present, this mechanism has highlighted the onset of the sound but has not explained yet which structure is responsible for the sound modulation. Interestingly, some acoustic features such as dominant frequency and pulse duration are directly related to fish size. Such variations are linked to a morphological constraint. Also, the existent relationship between fish size and swimbladder size implies that the swimbladder might be involved in the sound production. Sound analyses in Amphiprion clarkii showed that the experimental filling of the swimbladder with physiological liquid (NaCl 9‰) significantly modified the acoustic features. The most striking changes were a significant increase in dominant frequency and a significant decrease in pulse duration. These observations highlighted the implication of the swimbladder in sound modulation. In clownfishes, dominant frequency and pulse duration are morphologically determined signals. The swimbladder appears to modulate these acoustic features by acting as a resonant chamber. [less ▲]

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