Wall structure and material properties cause viscous damping of swimbladder sounds in the oyster toadfishOpsanus tau

Abstract

Despite rapid damping, fish swimbladders have been modelled as underwater resonant bubbles. Recent data suggest that swimbladders of soundproducing fishes use a forced rather than a resonant response to produce sound. The reason for this discrepancy has not been formally addressed, and we demonstrate, for the first time, that the structure of the swimbladder wall will affect vibratory behaviour. Using the oyster toadfish Opsanus tau, we find regional differences in bladder thickness, directionality of collagen layers (anisotropic bladder wall structure), material properties that differ between circular and longitudinal directions (stress, strain and Young's modulus), high water content (80%) of the bladder wall and a 300-fold increase in the modulus of dried tissue. Therefore, the swimbladder wall is a viscoelastic structure that serves to damp vibrations and impart directionality, preventing the expression of resonance.

Development and sexual dimorphism of the sonic system in three deep-sea neobythitine fishes and comparisons between upper mid and lower continental slope

“…We hypothesized that the tendons would be coupled with slow muscles whose contraction would put the tendons and swimbladder under strain that could result in multiple bladder oscillations upon muscle relaxation, depending on vibratory properties of the tendon (Parmentier and Fine, 2016) and restorative forces of the stretched swimbladder. We note that swimbladders not associated with tendons typically experience rapid damping (Fine et al, 2001(Fine et al, , 2009(Fine et al, , 2016Millot et al, 2011). Muscle contraction and tendon strain would pull the swimbladder forward and compress the ventral and lateral walls of the swimbladder.…”

Disturbance calls of five migratory Characiformes species and advertisement choruses in Amazon spawning sites

“…There is a wide diversity of independently‐derived sonic muscles in teleosts (Fine & Parmentier, ) and these have arisen as exaptations of structures used in other contexts such as buoyancy, swimming and feeding (Parmentier et al ., ). Sonic muscles may be intrinsic, attaching exclusively to the swimbladder, or extrinsic with a variably‐distant origin and attaching directly to the swimbladder or indirectly to a bone or tendon that moves the swimbladder (Ali et al ., ; Fine et al ., ; Fine & Parmentier, ). Within characiforms, several intercostal muscles have been modified into extrinsic drumming muscles that move the swimbladder indirectly by attached ribs or connecting to an aponeurosis surrounding the anterior swimbladder.…”

Ontogenetic change in predicted acoustic pressure sensitivity in larval red drum (Sciaenops ocellatus)

“…In considering the implications of bladder resonance for fish hearing, it is important to remember that our model includes only the swim bladder and otolith geometries in a sphere of water, leaving out the muscles and other tissues that will influence the cumulative response of the bladder to acoustic stimuli (e.g. McCartney and Stubbs, 1971;Sand and Hawkins, 1973;Fine et al, 2016). Tissues between the bladder and otoliths that have a viscosity greater than that of water would dampen the energy received at the otoliths from the bladder (Love, 1978;Feuillade and Nero, 1998), thus reducing the magnitude of the effect we observed.…”

“…Tissues between the bladder and otoliths that have a viscosity greater than that of water would dampen the energy received at the otoliths from the bladder (Love, 1978;Feuillade and Nero, 1998), thus reducing the magnitude of the effect we observed. Further, properties of the adult bladder wall can prevent it from acting as a resonant structure, drawing into question the appropriateness of modeling swim bladders as resonant bubbles (Fine, 2012;Fine et al, 2016). However, here we were interested in the larval stage; in the larval condition, swim bladders are thinwalled, even in species of chaetodontids and cichlids that have a thick tunica externa as adults (J. F. Webb, University of Rhode Island, personal communication).…”