Full Description

"Stimulation experiments on Carapus acus indicate that unlike other fish sonic muscles, the sonic muscle was surprisingly slow: a twitch averaged 490±3·ms (mean ± s.e.m., N=17) with contraction and relaxation times of approximately 110·ms and 380·ms, respectively."

"In C. acus, the dominant frequency of 340·Hz in each isolated pulse (Parmentier et al., 2006) does not correspond to the contraction rate of its sonic muscle, which tetanizes in the vicinity of 10·Hz."

Observation Environment Quotes

"Fish were stored in a community tank (0.6·m0.6·m0.4·m) with running seawater at 19°C. Recordings were made in a smaller tank (0.4·m0.4·m0.31·m). These fish were transported to the Aquarium Dubuisson (Liège, Belgium) where their sonic muscles were stimulated electrically."

Behaviour Description Quotes

"Fish were stored in a community tank (0.6·m0.6·m0.4·m) with running seawater at 19°C. Recordings were made in a smaller tank (0.4·m0.4·m0.31·m). These fish were transported to the Aquarium Dubuisson (Liège, Belgium) where their sonic muscles were stimulated electrically."

Sound Name Quotes

"In C. acus, the dominant frequency of 340·Hz in each isolated pulse (Parmentier et al., 2006) does not correspond to the contraction rate of its sonic muscle, which tetanizes in the vicinity of 10·Hz."

Full Description

"Slowly pulling the sonic muscles with forceps in deeply anesthetized specimens was sufficient to generate sound pulses (Fig.·6). The sound was produced during the manual extension when the hook released the tubercle, and the swimbladder snapped back to its resting position (Fig.·5). Therefore, the contraction speed is likely not important in generating a sound pulse; the role of the muscle is to provoke the decoupling of the hook anchored on the swimbladder. Manually generated sounds exhibited many similarities to voluntary sounds although they were shorter (pulse duration: 30.9±2.6·ms, N=37) than voluntary sounds (pulse duration: 73.5±0.05·ms, N=24) (t=13.40, d.f.=59, P<0.0001) and exhibited a slow exponential decay not previously seen in fish swimbladder sounds. Manually generated sounds had between 7 and 14 peaks compared to around 15 for natural sounds, but amplitude of the voluntary sound maintained a steadier level without the exponential decay."

"Voluntary Carapus boraborensis sounds were more sharply tuned (Q3dB=15, N=25; Q3dB=quotient of the dominant frequency divided by the bandwidth 3·dB down from the peak frequency) than manually generated sounds (4.3±0.3; P<0.001), but it is likely that opening the fish could have changed its vibratory properties."

"On the other hand, the pulse period was between 4.5 and 6.9·Hz in C. boraborensis (Parmentier et al., 2003a; Lagardère et al., 2005), which likely corresponds to the muscle contraction rate."

Observation Environment Quotes

"Following published protocol (Lagardère et al., 2005), a specimen of the host was placed in the centre of the tank, and several individual Carapus boraborensis were introduced successively into the aquarium. Sounds were recorded using an Orca hydrophone (sensitivity: –186·dB re 1V/uPa) connected via an Orca-made amplifier (ORCA Instrumentation, Brest, France) connected to a Sony TCD-D8 digital audio tape-recorder (recording band width: 20–22000·Hz ±1.0·dB)."

Behaviour Description Quotes

"Manually generated sounds were obtained by pulling the sonic muscles forward with forceps. They were recorded in a small vessel (38·cm28·cm5·cm) full of seawater as described above."

Sound Name Quotes

"Slowly pulling the sonic muscles with forceps in deeply anesthetized specimens was sufficient to generate sound pulses (Fig.·6). The sound was produced during the manual extension when the hook released the tubercle, and the swimbladder snapped back to its resting position (Fig.·5). Therefore, the contraction speed is likely not important in generating a sound pulse; the role of the muscle is to provoke the decoupling of the hook anchored on the swimbladder. Manually generated sounds exhibited many similarities to voluntary sounds although they were shorter (pulse duration: 30.9±2.6·ms, N=37) than voluntary sounds (pulse duration: 73.5±0.05·ms, N=24) (t=13.40, d.f.=59, P<0.0001) and exhibited a slow exponential decay not previously seen in fish swimbladder sounds. Manually generated sounds had between 7 and 14 peaks compared to around 15 for natural sounds, but amplitude of the voluntary sound maintained a steadier level without the exponential decay."