Retention of generalized hair cell patterns in the inner ear of the primitive flatfish psettodes

Flatfish are a group of uniquely asymmetrical vertebrates, lying always on one side. This postural control depends on the vestibular receptors of the inner ear. From the most primitive living flatfish, orientations of sensory hair cells in the inner ear were mapped by scanning electron microscopy. The maps of the three otolith organs, the three semicircular cristae, and the macula neglecta (newly discovered here for flatfish) show patterns that are very similar to those in many upright teleosts, particularly perches. Thus, peripheral sensory structure does not require modification for the unusual postural control of flatfish.