Fig. 2. Behaviors associated with sound production in the Hawaiian sergeant fish, Abudefduf abdominalis. (A) Nest preparation; males clean and prepare substrate adjacent to an existing nest (dotted circular area) and produce sounds when they scrape the substrate with their mouths, jaws and teeth. (B) Aggressive: males chase (arrow) both con- and heterospecific (e.g. egg-predator wrasse) intruders away from the nest area while producing short-pulse aggressive sounds. (C) Courtship–female-visit: males in blue nuptial coloration perform looping and zig-zag swims (solid arrow line) in the water column towards passing conspecific females. When a female follows the male back to the nest (broken arrow line), the courtship–female-visit sound is produced. Fish with a dotted outline in B and C represent the initial position, while fish with a solid outline represent the final position in the behavior sequence. Insets at the top left of A–C show example waveforms of sounds produced during each behavior. The recording hydrophone was positioned perpendicular to the plane of the page at about 1 m from the block spawning substrate. Scale bars, 100 ms.