Gross anatomy of the head lateral line and hearing system of the Ophidiinae, Genypterus blacodes, Raneya brasiliensis and Ophidion holbrookii, of Southern Brazil

Alberto Zavala-Camin, LuisMarcos Rotundo, Matheus

Cusk-eels (Ophidiinae) have been studied as fish that produce sound by using their swim bladder, but fish that are well-known for producing sound have a free swim bladder, associated with paired muscle. However, in addition to producing sound, the complex anatomy associated with the swim bladder of cusk-eels suggests that their hearing system is equivalent to or more complex than the Weberian apparatus of the Ostariophysi. The anatomy has been studied in fish caught in commercial shrimp fishery and dissected fresh or after being fixed in formalin; the bones were stained with alizarin; the head lateral lines were observed after skin removal and red syrup was then injected to enhance the lines on the head. The associated anatomy shows specializations in the head lateral line, the center of the swim bladder is fixed on the vertebrae, three specific muscles are associated and there are some exclusive organs, the complexity of which suggests great expertise in the perception of sound/pressure waves. Some hypotheses about their functions are presented in order to stimulate research into this subject.Key words: Fish. Lateral line. Sound/pressure detectors. Swimbladder.