Inner-ear morphology of the New Zealand Kiwi (Apteryx mantelli) suggests high-frequency specialization

Corfield, JR, Kubke, MF, Parsons, Stuart, & Koppl, C (2012) Inner-ear morphology of the New Zealand Kiwi (Apteryx mantelli) suggests high-frequency specialization. JARO - Journal of the Association for Research in Otolaryngology, 13(5), pp. 629-639.

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Abstract

The sensory systems of the New Zealand kiwi appear to be uniquely adapted to occupy a nocturnal ground-dwelling niche. In addition to well-developed tactile and olfactory systems, the auditory system shows specializations of the ear, which are maintained along the central nervous system. Here, we provide a detailed description of the auditory nerve, hair cells, and stereovillar bundle orientation of the hair cells in the North Island brown kiwi. The auditory nerve of the kiwi contained about 8,000 fibers. Using the number of hair cells and innervating nerve fibers to calculate a ratio of average innervation density showed that the afferent innervation ratio in kiwi was denser than in most other birds examined. The average diameters of cochlear afferent axons in kiwi showed the typical gradient across the tonotopic axis. The kiwi basilar papilla showed a clear differentiation of tall and short hair cells. The proportion of short hair cells was higher than in the emu and likely reflects a bias towards higher frequencies represented on the kiwi basilar papilla. The orientation of the stereovillar bundles in the kiwi basilar papilla showed a pattern similar to that in most other birds but was most similar to that of the emu. Overall, many features of the auditory nerve, hair cells, and stereovilli bundle orientation in the kiwi are typical of most birds examined. Some features of the kiwi auditory system do, however, support a high-frequency specialization, specifically the innervation density and generally small size of hair-cell somata, whereas others showed the presumed ancestral condition similar to that found in the emu.

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6 citations in Web of Science®

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ID Code: 79736
Item Type: Journal Article
Refereed: Yes
DOI: 10.1007/s10162-012-0341-4
Divisions: Current > Schools > School of Earth, Environmental & Biological Sciences
Current > QUT Faculties and Divisions > Science & Engineering Faculty
Copyright Owner: Springer
Deposited On: 20 Jan 2015 00:06
Last Modified: 21 Jan 2015 05:40

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