Form and function in the unique inner ear of a teleost:: The silver perch (Bairdiella chrysoura)

Members of the teleost family Sciaenidae show significant variation in inner ear and swim bladder morphology as well as in the relationship between the swim bladder and the inner ear. In the silver perch (Bairdiella chrysoura), a Stellifer-group sciaenid, both the saccular and utricular otoliths are enlarged relative to those in other teleosts. Additionally, its swim bladder is two-chambered, and the anterior chamber surrounds the otic capsule and terminates lateral to the saccules. Structure and function of the auditory system of the silver perch were explored by using gross dissections, scanning electron microscopy, CT scan reconstruction, and auditory brainstem response approach. Several morphological specializations of the auditory system of the silver perch were found, including expansion of the utricular and lagenar otoliths, close proximity between the saccules and the utricles, deeply grooved sulci on the saccular otoliths, two-planar saccular sensory epithelia, and a unique orientation pattern of sensory hair cell ciliary bundles on the saccular sensory epithelium. It was determined that the silver perch can detect up to 4 kHz, with lowest auditory thresholds between 600 Hz and 1 kHz. Audition in the silver perch is comparable to that in the goldfish (Carassius auratus), a hearing specialist. The morphological specializations of the inner ear and swim bladder of the silver perch may be linked to its enhanced hearing capabilities. The findings of this study support the proposal that sciaenids are excellent model species for investigating structure-function relations in the teleost auditory system. (C) 2004 Wiley-Liss, Inc.