Abstract :
[en] The ability to produce sounds has been reported in various Ostraciidae but not
deeply studied. In some Ostracion species, two different sound-producing muscles
allow these boxfishes to produce two different kinds of sounds in a sequence. This
study investigates sound production in another Indo-Pacific species, the longhorn
cowfish Lactoria cornuta that also possesses two pairs of sonic muscles associated
with the swim bladder: extrinsic sonic muscles (ESMs) and intrinsic sonic muscles
(ISMs). The cowfish produces two kinds of sounds called hums and clicks. Hums are
made of trains of low amplitude pulses that last for long periods of time, suggesting
that they are produced by fatigue-resistant muscles, whereas clicks correspond to
shorter sounds with greater amplitude than the hums, suggesting that they result
from more powerful contractions. Ultra-structural differences are found between
extrinsic and intrinsic sonic muscles. According to features such as long sarcomeres,
long I-bands, a high number of mitochondria, and a proliferation of sarcoplasmic reticulum
(SR), ESMs would be able to produce fast, strong, and short contractions corresponding
to clicks (the shortest sounds with the greatest amplitude). ISMs have the
thinnest cells, the smallest number of myofilaments that have long I-bands, the highest
volume of mitochondria, and well-developed SR supporting these muscles; these
features should generate fast and prolonged contractions that could correspond to
the hums that can be produced over long periods of time. A concluding figure shows
clear comparisons of the different fibers that were studied in L. cornuta. This study
also compared the call features of each sound with the cowfish's hearing ability and
supports L. cornuta was more sensitive to frequencies ranging between at least 100
and 400 Hz with thresholds of 128–143 dB re 1 μPa over this range, meaning that
they are sensitive to the frequencies produced by conspecifics.
Title :
Sound production, hearing sensitivity, and in-depth study of the sound-producing muscles in the cowfish (Lactoria cornuta)
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