bagvette

Eric Parmentier*, Jean-Paul Lagardère, Jean-Baptiste Braquegnier,
Pierre Vandewalle and Michael L. Fine

*Author for correspondence (e-mail: E.Parmentier@ulg.ac.be)


Fish sonic swimbladder muscles are the fastest muscles in vertebrates
and have fibers with numerous biochemical and structural adaptations
for speed. Carapid fishes produce sounds with a complex swimbladder
mechanism, including skeletal components and extrinsic sonic muscle
fibers with an exceptional helical myofibrillar structure. To study
this system we stimulated the sonic muscles, described their
insertion and action and generated sounds by slowly pulling the sonic
muscles. We find the sonic muscles contract slowly, pulling the
anterior bladder and thereby stretching a thin fenestra. Sound is
generated when the tension trips a release system that causes the
fenestra to snap back to its resting position. The sound frequency
does not correspond to the calculated resonant frequency of the bladder,
and we hypothesize that it is determined by the snapping fenestra
interacting with an overlying bony swimbladder plate. To our knowledge
this tension release mechanism is unique in animal sound generation.

Key words:
Carapidae, sound production, sonic muscle, sonic mechanism, swimbladder.


The Journal of Experimental Biology 209, 2952-2960
Published by The Company of Biologists 2006
doi:10.1242/jeb.02350


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