425
fi sh lateral line system. Using the gadiform fi sh Lota lota , they demonstrated that
local application of streptomycin to CN over several minutes transiently and reversibly suppressed lateral line microphonic potentials, opening up the possibility of
using aminoglycoside treatment as a tool in functional studies (Wersäll and Flock
1964 ). Most recent studies use bath immersion for one or more hours, rather than
short-term focal application, to deliver aminoglycosides to the entire lateral line
system, resulting in ablation (death) of sensory hair cells rather than short-term
functional suppression (e.g., Song et al. 1995 ; Buck et al. 2012 ; Suli et al. 2012 ;
Sampson et al. 2013 ).
Chemical ototoxins are important tools for studying the role of the lateral line in
feeding behavior. Both largemouth bass ( Micropterus salmoides ) and muskellunge
( Esox masquinongy ) altered their approach to a prey item when the lateral line was
inactivated with cobalt chloride (New et al. 2001 ; Gardiner and Motta 2012 ). Under
these conditions, bass increased pre-strike velocity and muskellunge changed their
approach angle, suggesting that near-fi eld vibratory stimuli contribute to a more
nuanced approach to prey capture (New et al. 2001 ; Gardiner and Motta 2012 ).
Similarly, lateral line ablation altered the orienting response of mottled sculpin
( Cottus bairdi ) to a vibrating (prey-like) stimulus (Coombs et al. 2001 ). In keeping
with the importance of the lateral line for feeding, larval striped bass ( Morone saxatilis ) prey-capture rates decreased following neomycin exposure, particularly for
fi sh tested in the dark (i.e., without visual cues) (Sampson et al. 2013 ). Furthermore,
experimentally blinded muskellunge have similar prey capture rates as sighted ones,
providing strong evidence that mechanosensory cues detected via the lateral line are
suffi cient for feeding (New et al. 2001 ). Selective physical ablation of superfi cial
neuromasts vs. chemical ablation of canal neuromasts with gentamicin (which selectively damages CN in some species, although see Van Trump et al. 2010 and Brown
et al. 2011 for evidence of damage to SN) suggests that orientation to a prey- like
stimulus depends primarily on canal neuromasts, at least in sculpin (Coombs et al.
2001 ). As sculpin are bottom dwelling “lie and wait” predators, it remains to be
determined if this fi nding applies to fi shes that use different prey capture strategies
or if species occupying similar ecological niches use the lateral line in similar ways.
Further evidence supporting the role of canal neuromasts in feeding comes from
recent comparative studies in cichlid fi shes, where canal morphology is correlated
with lateral line-mediated feeding behavior. Aulonocara stuartgranti , which has
wide canals and enlarged neuromasts, can feed successfully in both light and dark
conditions, based on video analysis of prey capture behavior (Schwalbe et al. 2012 ).
Inactivation of the lateral line with cobalt chloride inhibited the ability of these fi sh
to feed in the dark, demonstrating that without visual cues, the lateral line is necessary for prey detection and/or strike behavior (Schwalbe et al. 2012 ). In contrast,
cichlids from the genus Tramitichromis , which have narrow canals and smaller neuromasts, did not strike at prey in lightless conditions, and lateral line ablation did not
substantially alter prey capture behavior in the light (Schwalbe and Webb 2014 ).
Collectively, these data demonstrate that different fi shes rely on different combinations of sensory modalities for feeding, and that the lateral line is important for prey
detection and capture in some fi shes.
Chemical Ototoxicity of the Fish Inner Ear and Lateral Line
fi sh lateral line system. Using the gadiform fi sh Lota lota , they demonstrated that
local application of streptomycin to CN over several minutes transiently and reversibly suppressed lateral line microphonic potentials, opening up the possibility of
using aminoglycoside treatment as a tool in functional studies (Wersäll and Flock
1964 ). Most recent studies use bath immersion for one or more hours, rather than
short-term focal application, to deliver aminoglycosides to the entire lateral line
system, resulting in ablation (death) of sensory hair cells rather than short-term
functional suppression (e.g., Song et al. 1995 ; Buck et al. 2012 ; Suli et al. 2012 ;
Sampson et al. 2013 ).
Chemical ototoxins are important tools for studying the role of the lateral line in
feeding behavior. Both largemouth bass ( Micropterus salmoides ) and muskellunge
( Esox masquinongy ) altered their approach to a prey item when the lateral line was
inactivated with cobalt chloride (New et al. 2001 ; Gardiner and Motta 2012 ). Under
these conditions, bass increased pre-strike velocity and muskellunge changed their
approach angle, suggesting that near-fi eld vibratory stimuli contribute to a more
nuanced approach to prey capture (New et al. 2001 ; Gardiner and Motta 2012 ).
Similarly, lateral line ablation altered the orienting response of mottled sculpin
( Cottus bairdi ) to a vibrating (prey-like) stimulus (Coombs et al. 2001 ). In keeping
with the importance of the lateral line for feeding, larval striped bass ( Morone saxatilis ) prey-capture rates decreased following neomycin exposure, particularly for
fi sh tested in the dark (i.e., without visual cues) (Sampson et al. 2013 ). Furthermore,
experimentally blinded muskellunge have similar prey capture rates as sighted ones,
providing strong evidence that mechanosensory cues detected via the lateral line are
suffi cient for feeding (New et al. 2001 ). Selective physical ablation of superfi cial
neuromasts vs. chemical ablation of canal neuromasts with gentamicin (which selectively damages CN in some species, although see Van Trump et al. 2010 and Brown
et al. 2011 for evidence of damage to SN) suggests that orientation to a prey- like
stimulus depends primarily on canal neuromasts, at least in sculpin (Coombs et al.
2001 ). As sculpin are bottom dwelling “lie and wait” predators, it remains to be
determined if this fi nding applies to fi shes that use different prey capture strategies
or if species occupying similar ecological niches use the lateral line in similar ways.
Further evidence supporting the role of canal neuromasts in feeding comes from
recent comparative studies in cichlid fi shes, where canal morphology is correlated
with lateral line-mediated feeding behavior. Aulonocara stuartgranti , which has
wide canals and enlarged neuromasts, can feed successfully in both light and dark
conditions, based on video analysis of prey capture behavior (Schwalbe et al. 2012 ).
Inactivation of the lateral line with cobalt chloride inhibited the ability of these fi sh
to feed in the dark, demonstrating that without visual cues, the lateral line is necessary for prey detection and/or strike behavior (Schwalbe et al. 2012 ). In contrast,
cichlids from the genus Tramitichromis , which have narrow canals and smaller neuromasts, did not strike at prey in lightless conditions, and lateral line ablation did not
substantially alter prey capture behavior in the light (Schwalbe and Webb 2014 ).
Collectively, these data demonstrate that different fi shes rely on different combinations of sensory modalities for feeding, and that the lateral line is important for prey
detection and capture in some fi shes.
Chemical Ototoxicity of the Fish Inner Ear and Lateral Line