Neuroethology and Sensory Ecology of Teleost Ultrasound Detection

Recent discoveries have shown that some species of fish can detect frequencies as high as 180 kHz. This is well above what had been thought to be the limit of fish detection abilities but it remains unclear exactly how fish are performing this ultrasound detection. One obvious selective mechanism for evolution of ultrasound detection by fishes is prédation by echolocating odontocetes. Little evidence is available to either accept or refute this hypothesis however. The current chapter reviews the evidence for ultrasound detection in fish, both in the field and under laboratory conditions. Possible adaptations responsible for this detection ability are reviewed, with special emphasis on the morphology of the auditory system of fishes in the order Clupeiformes (the group most associated with ultrasound detection). The current state of our knowledge of the phylogenetics of the Clupeiformes does not allow definite testing of evolutionary hypotheses in this group but the current hypotheses concerning evolution of ultrasound detection in clupeiform fishes are discussed. The ecological consequences of ultrasound detection are stressed throughout the chapter, especially with regards to the behavioral ecology of predator: prey interactions as they may relate to odontocetes preying upon fish. Future experiments are encouraged that 1) examine how widespread is the ability to detect ultrasound, 2) assess the actual survival advantage of ultrasound detection in response to dolphin prédation, 3) determine the precise mechanism responsible for ultrasound detection, and 4) examine the developmental timing of ultrasound detection. It is not until these questions are answered that we can obtain a true picture of the evolution of ultrasound detection in teleosts.