82
4.3 Stimulation of the Lateral Line System in Chaetodon
and the Potential Effect of the Swim Bladder Horns
and LC
Body motions that generate sound produce dipole or higher order hydrodynamic fl ow
fi elds that can be directed towards a receiver fi sh. Butterfl yfi shes have a well- developed
set of cranial and trunk lateral line canals (and presumably superfi cial neuromasts on
the head and trunk) that can respond to these hydrodynamic stimuli. In addition to
stimulating the ear by whole body accelerations (as described above), such hydrodynamic fl ows generated by body motions produce steep pressure gradients across the skin
of the receiver that can stimulate the lateral line system at distances within a few body
lengths (Coombs and Montgomery 1999 ). Weak tail slaps by Chaetodon multicinctus
create slow fl uid vortices that impinge on the skin of the receiver fi sh (Hanke et al.
2008 ) and potentially provide information on the intensity and frequency components
of water velocity via superfi cial neuromasts and acceleration via canal neuromasts (as
defi ned by Kroese and Schellart 1992 ; Weeg and Bass 2002 ). The somatotopic organization of these hydrodynamic mechanoreceptors can potentially provide direction
and distance information for social stimuli as demonstrated for the detection of stimuli
generated by prey (Coombs et al. 1996 ). During territory border confl icts that occur
among pairs in several butterfl yfi sh species (Hourigan 1989 ; Tricas 1989 ; Tricas et al.
2006 ) such lateral-line mediated directional information may be complementary to
visual and auditory cues and provide unambiguous directional information, as proposed by Braun et al. ( 2002 ) and Coffi n et al. ( 2014 ). In addition, the mechanosensory
lateral line system may also be activated by sound pressure that is transduced by the
LC (see Sect. 2.1 ). Thus, coincident sound pressure information may be received by
both the ear and a portion of the lateral line canal system in the vicinity of the LC,
while different features of the hydrodynamic fl ow fi eld are detected by the ear and the
greater lateral line system. However, the transduction of sound pressure stimuli to the
mechanosensory lateral line via the LC awaits experimental confi rmation. Experiments
that involve the pharmacological or physical ablation of neuromasts are also needed
to determine the relative contribution of the lateral line and auditory systems to the
perception of an acoustic fi eld (Higgs and Radford 2013 ).
5 The Behavioral Ecology of Acoustic Communication
in Butterfl yfi shes
Sound production provides important information for social interactions in a wide
range of fi sh species (Myrberg and Lugli 2006 , reviewed by Ladich and Myrberg
2006 ). Honest signals provide accurate information about the condition of the signaler (Fitch and Hauser 2002 ) and can contribute to a dependable assessment of the
quality of an opponent. Evidence is accumulating that the acoustic stimuli generated
by butterfl yfi shes contain reliable information about the size or motivation of the
signaler, which may be important for decision-making in social contexts as reported
T.C. Tricas and J.F. Webb
4.3 Stimulation of the Lateral Line System in Chaetodon
and the Potential Effect of the Swim Bladder Horns
and LC
Body motions that generate sound produce dipole or higher order hydrodynamic fl ow
fi elds that can be directed towards a receiver fi sh. Butterfl yfi shes have a well- developed
set of cranial and trunk lateral line canals (and presumably superfi cial neuromasts on
the head and trunk) that can respond to these hydrodynamic stimuli. In addition to
stimulating the ear by whole body accelerations (as described above), such hydrodynamic fl ows generated by body motions produce steep pressure gradients across the skin
of the receiver that can stimulate the lateral line system at distances within a few body
lengths (Coombs and Montgomery 1999 ). Weak tail slaps by Chaetodon multicinctus
create slow fl uid vortices that impinge on the skin of the receiver fi sh (Hanke et al.
2008 ) and potentially provide information on the intensity and frequency components
of water velocity via superfi cial neuromasts and acceleration via canal neuromasts (as
defi ned by Kroese and Schellart 1992 ; Weeg and Bass 2002 ). The somatotopic organization of these hydrodynamic mechanoreceptors can potentially provide direction
and distance information for social stimuli as demonstrated for the detection of stimuli
generated by prey (Coombs et al. 1996 ). During territory border confl icts that occur
among pairs in several butterfl yfi sh species (Hourigan 1989 ; Tricas 1989 ; Tricas et al.
2006 ) such lateral-line mediated directional information may be complementary to
visual and auditory cues and provide unambiguous directional information, as proposed by Braun et al. ( 2002 ) and Coffi n et al. ( 2014 ). In addition, the mechanosensory
lateral line system may also be activated by sound pressure that is transduced by the
LC (see Sect. 2.1 ). Thus, coincident sound pressure information may be received by
both the ear and a portion of the lateral line canal system in the vicinity of the LC,
while different features of the hydrodynamic fl ow fi eld are detected by the ear and the
greater lateral line system. However, the transduction of sound pressure stimuli to the
mechanosensory lateral line via the LC awaits experimental confi rmation. Experiments
that involve the pharmacological or physical ablation of neuromasts are also needed
to determine the relative contribution of the lateral line and auditory systems to the
perception of an acoustic fi eld (Higgs and Radford 2013 ).
5 The Behavioral Ecology of Acoustic Communication
in Butterfl yfi shes
Sound production provides important information for social interactions in a wide
range of fi sh species (Myrberg and Lugli 2006 , reviewed by Ladich and Myrberg
2006 ). Honest signals provide accurate information about the condition of the signaler (Fitch and Hauser 2002 ) and can contribute to a dependable assessment of the
quality of an opponent. Evidence is accumulating that the acoustic stimuli generated
by butterfl yfi shes contain reliable information about the size or motivation of the
signaler, which may be important for decision-making in social contexts as reported
T.C. Tricas and J.F. Webb