73
and Karlsen 2000 ). This sound is generated by a tail slap locomotor behavior during
agonistic interactions with conspecifi cs (Fig. 6 ; Tricas et al. 2006 ; Tricas and Boyle
2015a ). The tail slap is a stereotyped motion of the body that follows other aggressive movements, such as a rapid approach or intense lateral display, which is
described in detail by Dewan and Tricas ( 2011 ). Swift movements of the lateral
body surface and tail creates a hydrodynamic acceleration that may produce complex vortices that impinge on the lateral body surface of the receiver fi sh (Hanke
et al. 2008 ), and at high intensities can displace a receiver’s body (Tricas et al.
2006 ). Whole body acceleration directly stimulates the ear of the receiver, but the
associated sound pressure wave is thought to produce only relatively small displacements of the wall of the swim bladder and swim bladder horns relative to
hydrodynamic motions from the source at frequencies <10 Hz, as modeled in the
cod swim bladder (Sand and Hawkins 1973 ). The tail slap behavior is most commonly observed in paired, monogamous, and territorial species such as C. multicinctus and C. ornatissimus , which aggressively defend food resources and mates.
The tail slap behavior is not commonly observed in planktivorous species such as
C. miliaris or C. kleinii , and is not yet described for other butterfl yfi sh genera. These
differences in aggressive behavior and the production of the tail slap sound among
butterfl yfi sh species are also associated with differential expression of arginine
vasotocin neuropeptide by neurons that project to the forebrain (Dewan et al. 2008 ,
2011 ; Dewan and Tricas 2011 , 2014 ). Further neuroanatomical and physiological
investigations are required to determine the proximate mechanisms responsible for
the central neural control of aggressive acoustic behaviors in butterfl yfi shes.
3.2 The Broad Palette of Butterfl yfi sh Sound Characteristics
The acoustic stimuli produced by Chaetodon species during social interactions span
a frequency range of at least four decades (<1 to >1000 Hz). Extreme low frequency
sounds with an average peak frequency of <10 Hz and long duration (400 ms) are
associated with the tail slap behavior in C. ornatissimus , C. multicinctus , and C.
unimaculatus (Tricas and Boyle 2015a ), and this sound is also produced by C.
auriga in the fi eld but is not yet quantifi ed (Tricas and Boyle unpublished observations). Other low frequency pulse sounds in the ~10–30 Hz range are produced by
C. multicinctus , C. ornatissimus , C. auriga , and Forcipiger via different mechanisms.
Sounds with higher peak frequencies of 100–1000 Hz are also readily produced
during social interactions in the lab by C. kleinii , C. unimaculatus , C. multicinctus ,
and Forcipiger . These have pulse durations of ≤50 ms and are similar with respect
to frequency and bandwidth characteristics. There is also great variation in the frequency range of sounds produced by different species (Tricas and Boyle 2014 ,
2015a ). For example, each Chaetodon species (with the exception of C. kleinii )
produces at least one sound type with a peak frequency of 1–30 Hz and another
sound type at 10–100 Hz. Sounds with peak frequency in the 10–100 Hz band can
include several sound types, and the 6 or 10 dB bandwidth of these sounds often
Acoustic Communication in Butterfl yfi shes…
and Karlsen 2000 ). This sound is generated by a tail slap locomotor behavior during
agonistic interactions with conspecifi cs (Fig. 6 ; Tricas et al. 2006 ; Tricas and Boyle
2015a ). The tail slap is a stereotyped motion of the body that follows other aggressive movements, such as a rapid approach or intense lateral display, which is
described in detail by Dewan and Tricas ( 2011 ). Swift movements of the lateral
body surface and tail creates a hydrodynamic acceleration that may produce complex vortices that impinge on the lateral body surface of the receiver fi sh (Hanke
et al. 2008 ), and at high intensities can displace a receiver’s body (Tricas et al.
2006 ). Whole body acceleration directly stimulates the ear of the receiver, but the
associated sound pressure wave is thought to produce only relatively small displacements of the wall of the swim bladder and swim bladder horns relative to
hydrodynamic motions from the source at frequencies <10 Hz, as modeled in the
cod swim bladder (Sand and Hawkins 1973 ). The tail slap behavior is most commonly observed in paired, monogamous, and territorial species such as C. multicinctus and C. ornatissimus , which aggressively defend food resources and mates.
The tail slap behavior is not commonly observed in planktivorous species such as
C. miliaris or C. kleinii , and is not yet described for other butterfl yfi sh genera. These
differences in aggressive behavior and the production of the tail slap sound among
butterfl yfi sh species are also associated with differential expression of arginine
vasotocin neuropeptide by neurons that project to the forebrain (Dewan et al. 2008 ,
2011 ; Dewan and Tricas 2011 , 2014 ). Further neuroanatomical and physiological
investigations are required to determine the proximate mechanisms responsible for
the central neural control of aggressive acoustic behaviors in butterfl yfi shes.
3.2 The Broad Palette of Butterfl yfi sh Sound Characteristics
The acoustic stimuli produced by Chaetodon species during social interactions span
a frequency range of at least four decades (<1 to >1000 Hz). Extreme low frequency
sounds with an average peak frequency of <10 Hz and long duration (400 ms) are
associated with the tail slap behavior in C. ornatissimus , C. multicinctus , and C.
unimaculatus (Tricas and Boyle 2015a ), and this sound is also produced by C.
auriga in the fi eld but is not yet quantifi ed (Tricas and Boyle unpublished observations). Other low frequency pulse sounds in the ~10–30 Hz range are produced by
C. multicinctus , C. ornatissimus , C. auriga , and Forcipiger via different mechanisms.
Sounds with higher peak frequencies of 100–1000 Hz are also readily produced
during social interactions in the lab by C. kleinii , C. unimaculatus , C. multicinctus ,
and Forcipiger . These have pulse durations of ≤50 ms and are similar with respect
to frequency and bandwidth characteristics. There is also great variation in the frequency range of sounds produced by different species (Tricas and Boyle 2014 ,
2015a ). For example, each Chaetodon species (with the exception of C. kleinii )
produces at least one sound type with a peak frequency of 1–30 Hz and another
sound type at 10–100 Hz. Sounds with peak frequency in the 10–100 Hz band can
include several sound types, and the 6 or 10 dB bandwidth of these sounds often
Acoustic Communication in Butterfl yfi shes…