Original Paper

Journal of Comparative Physiology A

, Volume 192, Issue 3, pp 267-277

Ossicular differentiation of airborne and seismic stimuli in the Cape golden mole (Chrysochloris asiatica)

  • U. B. WilliAffiliated withDepartment of Physiological Science, University of California at Los Angeles
  • , G. N. BronnerAffiliated withDepartment of Zoology, University of Cape Town
  • , P. M. NarinsAffiliated withDepartment of Physiological Science and Department of Ecology & Evolutionary Biology, University of California at Los Angeles Email author 

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Abstract

Comparison between the middle ear anatomy of the Cape golden mole (Chrysochloris asiatica), which exhibits a club-shaped malleus head, and the Desert golden mole (Eremitalpa granti), with a ball-shaped malleus head, suggests differences in sensitivity to airborne sound. Scanning laser Doppler vibrometric measurements of the ossicular behavior in response to both vibration and airborne sound were made in C. asiatica. Two distinct vibrational modes were observed. In response to low-frequency vibration (70–200 Hz), the malleus oscillates about the ligament of the short process of the incus, whereas in response to high-frequency airborne sound (1–6 kHz) the ossicular chain rotates about the long axis of malleus. It is proposed that the club-shaped malleus head in C. asiatica constitutes an adaptation towards bimodal hearing—sensitivity to substrate vibrations and airborne sound. Possible functional differences between these two middle ear types are discussed.

Keywords

Middle ear Bimodal Sound Vibration Chysochloridae