Ear and hearing in Sphenodon punctatus

Abstract

Observations on Sphenodon punctatus have revealed new features of the anatomy of the ear, and measurements in a living specimen by means of cochlear potentials show the form and level of this ear's performance in sound reception. For an animal lacking an external ear opening and a functional tympanic membrane, the sensitivity of from 100-900 Hz is surprisingly good in low tones with peak response around 200-400 Hz. The inner ear is well developed, with a tectorial membrane connected to a tectorial plate that extends throughout the cochlea. The best region of sensitivity agrees well with the main frequency components of the animal's vocalizations.