WILLIAM N. TAVOLGA
166
those of the lagena, were shown to respond to both vibratory and static
bending ( Furukawa and Ishii, 1967a,b). Using neurophysiological techniques, some determinations of hearing capacities have been made in
herring, Clupea, codfish, Gadus, and sculpin, Cottus, by Enger (1963,
1967a) and Enger and Andersen (1967). The connections between
acoustic nerve fibers and Mauthner's neurons were reviewed by Moulton
and Dixon (1967), together with extensive discussion and evidence for
the relation of these connections to directional responses to sound in
fishes.
2. SWIM BLADDER AND HEARING
According to Griffin (1950, 1955) and Pumphrey (1950), a fish is
essentially transparent to water-borne sound and its only acoustic discontinuity is the swim bladder (or other air chamber). Sound reception
under water requires the presence of a transducer constructed of material
very different in acoustic properties and density from the surrounding
medium. Air bubbles are known to be excellent reflectors and resonators
(Horton, 1959; Meyer, 1957) and certainly the swim bladder can serve
efficiently as a transducer. Jones and Pearce (1958), N. B. Marshall
(1951), and Midttun and Hoff (1962) have shown that fish swim bladders
are effective sonic reflectors and that 50% or more of impinging sound
energy is returned by the bladder, while a smaller percentage is reflected
by the rest of the fish's body. Kleerekoper and Roggenkamp (1959) demonstrated that damage to the swim bladder in the catfish, Zctalurus, raised
thresholds by 20 dB or more. It is quite probable, however, that some
portions of the fish, such as the skull, may also serve as acoustic discontinuities and thus permit sound reception by bone conduction, although
the swim bladder still appears to be the most obvious and efficient sonic
transducer that the fish possesses.
If the above is correct, then fishes with swim bladders should have
better hearing than those without. Furthermore, those species in which
the swim bladder is acoustically coupled to the inner ear should have the
highest auditory sensitivity and broadest range.
It appears that the Ostariophysi possess the lowest auditory thresholds
and highest upper frequency limits. This is undoubtedly a function of the
Weberian apparatus which couples the auditory signal received by the
swim bladder to the inner ear in a manner analogous to the operation of
the middle ear ossicles in mammals. Other air chambers can serve in
similar fashion, as, for example, the branchial cavity in the labyrinthine
fishes ( Schneider, 1941).
Among nonostariophysines, there are a number of forms in which the
166
those of the lagena, were shown to respond to both vibratory and static
bending ( Furukawa and Ishii, 1967a,b). Using neurophysiological techniques, some determinations of hearing capacities have been made in
herring, Clupea, codfish, Gadus, and sculpin, Cottus, by Enger (1963,
1967a) and Enger and Andersen (1967). The connections between
acoustic nerve fibers and Mauthner's neurons were reviewed by Moulton
and Dixon (1967), together with extensive discussion and evidence for
the relation of these connections to directional responses to sound in
fishes.
2. SWIM BLADDER AND HEARING
According to Griffin (1950, 1955) and Pumphrey (1950), a fish is
essentially transparent to water-borne sound and its only acoustic discontinuity is the swim bladder (or other air chamber). Sound reception
under water requires the presence of a transducer constructed of material
very different in acoustic properties and density from the surrounding
medium. Air bubbles are known to be excellent reflectors and resonators
(Horton, 1959; Meyer, 1957) and certainly the swim bladder can serve
efficiently as a transducer. Jones and Pearce (1958), N. B. Marshall
(1951), and Midttun and Hoff (1962) have shown that fish swim bladders
are effective sonic reflectors and that 50% or more of impinging sound
energy is returned by the bladder, while a smaller percentage is reflected
by the rest of the fish's body. Kleerekoper and Roggenkamp (1959) demonstrated that damage to the swim bladder in the catfish, Zctalurus, raised
thresholds by 20 dB or more. It is quite probable, however, that some
portions of the fish, such as the skull, may also serve as acoustic discontinuities and thus permit sound reception by bone conduction, although
the swim bladder still appears to be the most obvious and efficient sonic
transducer that the fish possesses.
If the above is correct, then fishes with swim bladders should have
better hearing than those without. Furthermore, those species in which
the swim bladder is acoustically coupled to the inner ear should have the
highest auditory sensitivity and broadest range.
It appears that the Ostariophysi possess the lowest auditory thresholds
and highest upper frequency limits. This is undoubtedly a function of the
Weberian apparatus which couples the auditory signal received by the
swim bladder to the inner ear in a manner analogous to the operation of
the middle ear ossicles in mammals. Other air chambers can serve in
similar fashion, as, for example, the branchial cavity in the labyrinthine
fishes ( Schneider, 1941).
Among nonostariophysines, there are a number of forms in which the