01923nas a2200169   4500008004100000022001300041245007400054210006900128260001600197300001600213490000700229520139000236100001801626700002201644700002001666856006701686       2019                        eng d  a0960982200aRemarkably loud snaps during mouth-fighting by a sponge-dwelling worm0 aRemarkably loud snaps during mouthfighting by a spongedwelling w  cJan-07-2019  aR617 - R6180 v293 a<p>Many aquatic animals, including mammals, fishes, crustaceans and insects, produce loud sounds underwater 1, 2, 3, 4, 5, 6. Soft-bodied worms would seem unlikely to produce a loud snap or pop because such brief, intense sounds normally require extreme movements and sophisticated energy storage and release mechanisms [5]. Surprisingly, we discovered a segmented marine worm that makes loud popping sounds during a highly stereotyped intraspecific agonistic behavior we call &lsquo;mouth fighting&rsquo;. These sounds &mdash; sound pressures up to 157 dB re 1 &mu;Pa at 1 m, with frequencies in the 1&ndash;100 kHz range and a strong signal at &sim;6.9 kHz &mdash; are comparable to those made by snapping shrimps, which are among the most intense biological sounds that have been measured in the sea [6]. We suggest a novel mechanism for generating ultrafast movements and loud sounds in a soft-bodied animal: thick, muscular pharyngeal walls appear to allow energy storage and cocking; this permits extremely rapid expansion of the pharynx within the worm&rsquo;s body during the strike, which yields an intense popping sound (likely via cavitation) and a rapid influx of water. Clearly, even soft-bodied marine invertebrates can produce remarkably loud sounds underwater. How they do so remains an intriguing biomechanical puzzle that hints at a new type of extreme biology.</p>
1 aGoto, Ryutaro1 aHirabayashi, Isao1 aPalmer, Richard  uhttps://linkinghub.elsevier.com/retrieve/pii/S0960982219306177