Directional asymmetry of middle-ear ossicles in the free-tailed Mexican bat Tadarida brasiliensis

T. Lifschytz*, E. Tchernov, Y. L. Werner

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

The mammalian hearing system uses several spectral cues to determine the location of a sound source in space. Of these, the time difference of the soundwaves' arrival to the two ears and their intensity difference are of utmost importance. Bats use their hearing system to locate sound sources in the dark in a process called echolocation: the bat emits pulses of sound toward a target in space, and determines its position by analysis of the returning echoes. The target may be an insect prey or a predator to avoid. In the absence of other reliable sensory inputs in the dark, an utmost accuracy in sound localization is essential for survival. The fact that the bat has to rely on the input of acoustic waves in order to detect targets in the dark (especially prey), without always being able to use its vision to correct for localization mistakes, may cause certain problems in the dark. The most important of those is "localization ambiguity" (LA), i.e., the situation in which the arrival time and intensity differences between the two ears may correspond to several locations in space. Our hypothesis was that the bat may have evolved directional asymmetries in the middle ear ossicles, which may help resolve the LA problem by providing the animal with additional frequency information of the incoming soundwaves. Middle-ear ossicles were obtained from Tadarida brasiliensis skulls collected from a cave floor in New Mexico. The skulls were chemically treated in a heated KOH solution before the surgical extraction of the ossicles. Measurements were performed on computer-digitized pictures obtained by an image analyzer. Preliminary measurements indicate directional asymmetry in some characters.

Original languageEnglish
Pages (from-to)166-167
Number of pages2
JournalIsrael Journal of Zoology
Volume46
Issue number2
StatePublished - 2000

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