Morphometric analysis of ears in two families of pinnipeds
Marsh, Sarah Elizabeth
MetadataShow full item record
Pinniped (seal and sea lion) auditory systems operate in two acoustically distinct environments, air and water. Piniped species differ in how much time they typically spend in water. They therefore offer an exceptional opportunity to investigate aquatic versus terrestrial hearing mechanisms. The Otariidae (sea lions and fur seals) generally divide their time evenly between land and water and have several adaptations; e.g. external pinnae, related to this lifestyle. Phocidae (true seals) spend the majority of their time in water; they lack external pinnae and have well developed ear canal valves. Differences in hearing ranges and sensitivities have been reported recently for members of both of these familes (Kastak, D., Schusterman, RJ., 1998. Low frequency amphibious hearing in pinnipeds. J. Acoust. Soc. Am. 1303,2216- 2228.; Moore, P.W.B., Schusterman, RJ., 1987. Audiometric assessment of northern fur seals, Callorhinus ursinus. Mar. Mamm. Sci. 3,31-53.). In this project, the ear anatomy of three species of pinnipeds: an otariid, the California sea lion (Zalophus californianus), and two phocids, the northern elephant seal (Mirounga angustirostris) and the harbor seal (Phoca vitulina), was examined using computerized tomography (CT scans) and gross dissection. Thee-dimensional reconstructions of the heads and ears from CT data were used to determine interaural dimensions and ossicular chain morphometrics. Ossicular weights and densities were measured conventionally. Results strongly support a canalcentric system for pinniped sound reception and localization. Further, true seals show adaptations for aquatic high frequency specialization.
Submitted in partial fulfillment of the requirements for the degree of Master of Science at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution August 2001
Showing items related by title, author, creator and subject.
Xenobiotic monooxygenase activity and the response to inducers of cytochrome P-450 during embryonic and larval development in fish Binder, Robert L. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1981-08)Data demonstrating the presence and inducibility of the xenobiotic monooxygenase system in fish embryos and larvae are described. The ontogeny of benzo(a)pyrene monooxygenase (BPM) activity, and NADPH- and NADH-cytochrome ...
Observations of interaction between the internal wavefield and low frequency flows in the North Atlantic Ruddick, Barry R. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1977-04)A total of four moorings from POLYMODE Array I and II were analyzed in an investigation of internal wavefield-mean flow interactions. In particular, evidence for wave-mean flow interaction was sought by searching for ...
Dewar, William K. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1982-10)Four different problems concerning Gulf Stream Rings are considered. The first deals with the particle trajectories of, and advection-diffusion by, a dynamic model of a Ring. It is found that the streaklines computed ...