200
behavior and social interactions. I also had become familiar with their vocal behavior
(Tavolga 1958, 1964). The locally available species was an obvious choice in which
to address questions about how a fish locates a vocalizing conspecific. Arthur
Popper approved, and thus began more than 20 years of research on auditory processing in oyster toadfish.
This review of research completed during collaborations with Arthur Popper and
Richard Fay not only summarizes some of the important contributions to understanding what toadfish (and other teleosts) hear but also reflects their influence on
the questions asked, the hypotheses generated, and the interpretation of the data
obtained. None of this research would have taken place without them.
The focus of my research has been on how the toadfish ear and central nervous
system encode and process sounds of biological significance. Sound consists of the
alternating compression and rarefaction of the medium through which sound travels, producing both a pressure wave and particle motion. Although some fish can
detect the pressure component of sound through an indirect mechanism (involving
an internal, gas-filled structure), all fish ears respond directly to the particle motion
component (Popper and Fay 2011). Lu (2011) provides an excellent introduction to
auditory processing in fishes in general and Radford et al. (2012) provide an experimental comparison of particle motion and pressure stimulation among three teleost
species that differ in the presence or absence of an association between the ear and
the gas bladder. The physiological research that we conducted on toadfish has investigated only how the toadfish ear responds to particle motion and how the vector of
particle motion is encoded in the central nervous system as the basis for determining
the location of a sound source.
As in other vertebrates, the ear in fishes has three orthogonal semi-circular canals
and three otolithic endorgans that provide information about the position and movement of the head (orientation with respect to gravity, linear acceleration, angular
acceleration). The reader is referred to Straka and Baker (2011) for a general introduction to the vestibular (or positional) sense, which is fairly consistent across species and is applicable to what the toadfish ear tells the toadfish brain with regard to
position. Unlike other vertebrates, one or more of the three otolithic endorgans in
fishes encode the particle motion component of sound. The otolithic endorgan acts
as an inertial accelerometer: the sensory hair cells are stimulated by the shearing
motion caused by relative motion of the sensory epithelium with respect to the
much denser, calcareous otolith. The sensory hair cells are oriented in various directions on the endorgan, resulting in response characteristics across the endorgan that
could be used to compute the direction of the sound source in 3-dimensional space
(see Sect. 3.1). The focus of this paper will be what we have learned about what the
toadfish ear tells the toadfish brain about the particle motion component of sound.
The behavioral repertoire of oyster toadfish includes the establishment of reproductive territories around a nest site constructed by males, sound production in both
agonistic and reproductive contexts, and behavioral responses to conspecific sounds
by both sexes (Gray and Winn 1961; Winn 1972; Fish 1972). Behavioral observations confirm that multiple reproductive males do not occupy the same nest sites,
and that females are attracted to nest sites with vocal males (Gray and Winn 1961;
P.L. Edds-Walton
behavior and social interactions. I also had become familiar with their vocal behavior
(Tavolga 1958, 1964). The locally available species was an obvious choice in which
to address questions about how a fish locates a vocalizing conspecific. Arthur
Popper approved, and thus began more than 20 years of research on auditory processing in oyster toadfish.
This review of research completed during collaborations with Arthur Popper and
Richard Fay not only summarizes some of the important contributions to understanding what toadfish (and other teleosts) hear but also reflects their influence on
the questions asked, the hypotheses generated, and the interpretation of the data
obtained. None of this research would have taken place without them.
The focus of my research has been on how the toadfish ear and central nervous
system encode and process sounds of biological significance. Sound consists of the
alternating compression and rarefaction of the medium through which sound travels, producing both a pressure wave and particle motion. Although some fish can
detect the pressure component of sound through an indirect mechanism (involving
an internal, gas-filled structure), all fish ears respond directly to the particle motion
component (Popper and Fay 2011). Lu (2011) provides an excellent introduction to
auditory processing in fishes in general and Radford et al. (2012) provide an experimental comparison of particle motion and pressure stimulation among three teleost
species that differ in the presence or absence of an association between the ear and
the gas bladder. The physiological research that we conducted on toadfish has investigated only how the toadfish ear responds to particle motion and how the vector of
particle motion is encoded in the central nervous system as the basis for determining
the location of a sound source.
As in other vertebrates, the ear in fishes has three orthogonal semi-circular canals
and three otolithic endorgans that provide information about the position and movement of the head (orientation with respect to gravity, linear acceleration, angular
acceleration). The reader is referred to Straka and Baker (2011) for a general introduction to the vestibular (or positional) sense, which is fairly consistent across species and is applicable to what the toadfish ear tells the toadfish brain with regard to
position. Unlike other vertebrates, one or more of the three otolithic endorgans in
fishes encode the particle motion component of sound. The otolithic endorgan acts
as an inertial accelerometer: the sensory hair cells are stimulated by the shearing
motion caused by relative motion of the sensory epithelium with respect to the
much denser, calcareous otolith. The sensory hair cells are oriented in various directions on the endorgan, resulting in response characteristics across the endorgan that
could be used to compute the direction of the sound source in 3-dimensional space
(see Sect. 3.1). The focus of this paper will be what we have learned about what the
toadfish ear tells the toadfish brain about the particle motion component of sound.
The behavioral repertoire of oyster toadfish includes the establishment of reproductive territories around a nest site constructed by males, sound production in both
agonistic and reproductive contexts, and behavioral responses to conspecific sounds
by both sexes (Gray and Winn 1961; Winn 1972; Fish 1972). Behavioral observations confirm that multiple reproductive males do not occupy the same nest sites,
and that females are attracted to nest sites with vocal males (Gray and Winn 1961;
P.L. Edds-Walton