A personal account of work on anatomy, physiology, and behavior of fish sound production

Abstract

My research has been devoted to neuromuscular control of sound production in toadfish, catfish, and other species along with an occasional foray into hearing. Toadfish utilize a heart shaped swim bladder and superfast muscles with small fibers and an unusual ultrastructure. Both sonic motor neurons and muscle fibers increase in size and number for multiple years, and large muscle fibers fragment and likely divide, maintaining energetic efficiency. Toadfish sonic muscles drive the swim bladder directly (a forced response), and the sound waveform parallels bladder movement. The forced response differs from traditional interpretations of swim bladders as underwater resonant bubbles. High water content in the swim bladder wall inhibits resonance by viscous damping at shallow but likely less effectively at deeper depths, suggesting both notions might apply. Catfish produce sounds with their pectoral spines by rubbing a ridged surface on the dorsal process against a rough surface on the cleithrum: a series of quick jerks produce sounds via a slip-stick mechanism. Recent discoveries on other species reveal novel adaptations for sound production and suggestions are made for future work.