Movement and sound generation by the toadfish swimbladder

Abstract

Although sound-producing (sonic) muscles attached to fish swimbladders are the fastest known vertebrate muscles, the functional requirement for such extreme speed has never been addressed. We measured movement of the swimbladder caused by sonic muscle stimulation in the oyster toadfish Opsanus tau and related it to major features of the sound waveform. The movement pattern is complex and produces sound inefficiently because the sides and bottom of the bladder move in opposite in and out directions, and both movement and sound decay rapidly. Sound amplitude is related to speed of swimbladder movement, and slow movements do not produce perceptible sound. Peak sound amplitude overlaps fundamental frequencies of the male's mating call because of muscle mechanics and not the natural frequency of the bladder. These findings suggest that rapid muscle speed evolved to generate sound from an inefficient highly damped system.

Vocal production complexity correlates with neural instructions in the oyster toadfish (Opsanus tau)

“…Although 'tethered' by the electrode wires, the preparation allowed investigation of an intact system in a freely swimming animal. Rhythmic VN stimulation volleys up to 300 Hz showed no irregular P1 waveforms (Figs 1, 2), which contrasts with previous a report on toadfish removed from the water where the first few cycles of contraction were partially fused before the muscle exhibited regular contractions at frequencies over 200 Hz (Fine et al, 2001). At the onset of nerve stimulation bursts, we observed a gradual increase of sound amplitude in all fish during the first six to 10 stimuli (Fig.…”

“…An excellent model system to study the interactions between neural control and peripheral mechanics in sound production is the batrachoidid fishes (midshipman and toadfish), which produce sound by swimbladder wall movements (Fine et al, 2009;Fine et al, 2001;Skoglund, 1961) actuated by pure-fibre superfast muscles that are among the fastest vertebrate skeletal muscles (Rome, 2006;Rome et al, 1996). Each swimbladder muscle (SBM) is innervated by vocal motor neurons specialised for superfast muscles (Chagnaud et al, 2012) and receives input from a vocal network consisting of distinct hindbrain nuclei (Chagnaud et al, 2011).…”

The outcome of male–male encounters affects subsequent sound production during courtship in the cichlid fish Oreochromis mossambicus

“…The 'resonance hypothesis' proposes that the peak frequency of pulsed sounds is imparted by the resonance characteristics of the swimbladder causing this feature to be size dependent (Harris 1964;Myrberg et al 1993). More recently, Connaughton et al (2000) and Fine et al (2001) have put forward the 'forced response' hypothesis, which suggests that the dominant frequency of fish pulsed sounds involving a swimbladder results from the forced response of the sonic muscles. In this case, the peak frequency of sounds depends on the duration of muscle contraction, which is dependent on body scaling (e.g.…”

Novel vocal repertoire and paired swimbladders of the three-spined toadfish,Batrachomoeus trispinosus: insights into the diversity of the Batrachoididae

“…More detailed biomechanical studies of each swimbladder (e.g. Fine et al, 2001) will be required to better understand the role of dimorphisms in sound production.…”

“…Vocalizations are produced by the rapid contraction of paired striated muscles attached to the walls of the swimbladder (Fine et al, 2001;Fine et al, 2002), with ultrastructural traits divergent from trunk skeletal muscles (e.g. Bass and Marchaterre, 1989;Fawcett and Revel, 1961), that are adapted to contraction frequencies which are among the fastest of vertebrate skeletal muscles (Rome, 2006;Rome et al, 1996;Skoglund, 1961).…”