Stereolepis gigas
Five putative sonic muscles were discovered between each of the first six pleural ribs of the male examined (Fig. 2). These five massive muscles (1⁄4obliquus superioris?) unite ribs 3 to 9 and were found at the level of the hypaxial musculature. Histological examination confirmed this tissue to be striated muscle tissue with elongate multinucleate cells with striations (Fig. 2). These extrinsic muscles were notably missing from the verified, mature female that was examined post-mortem. The pleural ribs were rostro-posteriorly flattened, canted, and found to sit directly adjacent and parallel to the lateral wall of the swimbladder. Further, the ribs were hinged to their respective vertebrae (3 to 8), allowing the ribs to pivot and deform the swimbladder. The muscle fibers of the tissue run obliquely between the ribs, originating on the posterior edge of the leading rib and inserting more distally on the anterior margin of following rib.
Manual traction of these ribs and muscles pulled ribs 2 to 6 medially and rostrally. No corresponding muscle tissue was found originating on the head and inserting on the ribs of either mature fish examined. [1]
References
Four basic sounds plus combi- nations were identified from the tank recordings when fish were present and were encountered on numerous occasions throughout the study. We classified the basic sounds as two types of pulses (A and B), short bursts, and long bursts, and combinations of short and long bursts (Fig. 1). Mean peak frequencies of the four sound types were less than 39 Hz, while mean durations ranged from 67 ms to 545 ms, depending on sound type (Table 1). Short bursts were similar to the sounds we earlier characterized as ‘‘booms’’ (Clark and Allen, 2018) although the peak frequencies were lower in the tank than in the wild. The short and long bursts along with their combinations are new to the Giant Sea Bass sound repertoire and only occurred during spawning events (the eve and night of spawn verified by fertilized egg collection). None of the four sound types were recorded in the absence of fish during control recordings. [1]