Ultrasound Detection in Fishes and Frogs: Discovery and Mechanisms

The frequency range of hearing in fishes and frogs historically has been thought to be confined to relatively low frequencies in comparison to mammals (Hawkins, 1981; Fay, 1988). The fishes with the greatest sensitivity and frequency bandwidth, such as the otophysans, a group of species that have a mechanical coupling between the swim bladder and inner ear, have upper frequency sensitivities below 5 kHz (Fay, 1988). Similarly for frogs, audiogram studies typically have tested only up to 4–5 kHz (Fay, 1988). However, there have been hints of higher frequency sensitivity in some fishes and frogs. In 1982 Boyd Kynard discovered that ultrasonic sonar (about 160 kHz) caused behavioral responses in migrating Alosa sapidissima (Kynard & O’Leary, 1990).