Printed in Great Britain THE RESPONSE OF THE SWIM BLADDER OF THE GOLDFISH {CARASSIUS AURATUS) TO ACOUSTIC STIMULI

The teleost swim bladder is a gas-filled chamber located in the abdominal cavity just below the vertebral column. It consists of one or more inter-connected chambers which may be partially divided into ' subchambers ' by septa that are extensions of the inner lining of the swim-bladder wall (Demski, Gerald & Popper, 1973; Greene, 1924; Tavolga, 1962 and others). The swim bladder appears to have multiple roles in fish behaviour. One major function is as a hydrostatic organ involved in control of the density of the fish through changes in the amount of gas within the bladder (Steen, 1970). A second role in many species is in the production and detection of sounds (see reviews by Demski et al. 1973; Lowenstein, 1971; Popper & Fay, 1973; Tavolga, 1971). During the production of certain types of sound the swim bladder acts as an acoustic transformer between the water and vibrating body structure (e.g. muscles) (Demski et al. 1973; Harris, 1964; Tavolga, 1962; Skoglund, 1959, 1961). While the role in sound detection is not as clear as the role in sound production, the gas-filled bladder is of considerably different density from sea water and so it presents an impedance discontinuity that woul