Acoustic Behaviour in Fish –

Abstract

It has long been known that some fish can be acoustically active. But the assumption that the vast majority of fish spend their life without emitting sound is still widespread. A recent study has shown that the number of potentially acoustically active fish is much higher than previously assumed. Fish emit sound in a variety of contexts, most notably during agonistic encounters and during reproduction. The acoustic signal is a fundamental element of social communication, sometimes even more important than visual displays. Sounds are produced primarily by vibrations of the swimbladder or by rigid structures rubbing against each other, termed stridulation. The small acoustic repertoire and simplicity of the sounds make acoustic fish excellent model organism. The neural control of acoustic communication has been studied mainly in toadfishes, which emit tonal courtship sounds, largely by a group led by Andrew H. Bass. Toadfish calls are structured in the vocal pattern generating circuit of the hindbrain. Call characteristics, such as duration, appear to be regulated by vocal centres in the mid- and forebrain, as well as by certain neuropeptides. In this review, I will outline behavioural and seasonal / diurnal aspects of acoustic communication in fish. Furthermore, I will elucidate the pattern generating circuit in the hindbrain and discuss aspects of call modulation controlled by the mid- and forebrain. At the end, I will present some questions that need further research, such as exploring the neural control of stridulation.