AUDITORY SENSITIVITY IN THE FAN-TOED GECKO, Ptyodactylus hasselquistii BOUTAN

Abstract

Measurements of cochlear potentials were carried out in a series of 15 geckos, Ptyodactylus hasselquistii puiseuxi, especially the sensitivity of the ears, the efficiency of the middle-ear mechanism, and the variation of cochlear output as a function of sound pressure. The ears of these animals were most sensitive in the region of 700-1,000 cycles/sec, which is fairly similar to the forms of sensitivity functions seen in other gecko species and the degree of sensitivity exhibited is the best seen in any lizard ear. The observation of intensity functions containing multiple maximums is interpreted as indicating the presence of frequency differentiation in terms of place along the basilar membrane. There was a progressive development of structure in lizards showing in the more advanced types a discrimination of tones by the place principle.