Elastic modulus of cetacean auditory ossicles

TitleElastic modulus of cetacean auditory ossicles
Publication TypeJournal Article
Year of Publication2014
AuthorsTubelli, A. A., A. L. Zosuls, D. R. Ketten, and D. C. Mountain
JournalThe Anatomical Record
Start Page892
Date Published02/2014
Type of ArticleScientific
Keywordsauditory, basilar membrane, cetacean hearing, dolphin ear, dolphin hearing, elastic modulus, incus, malleus, marine mammal hearing, middle ear, ossicles, stapes, whale ear, whale hearing

In order to model the hearing capabilities of marine mammals (cetaceans), it is necessary to understand the mechanical properties, such as elastic modulus, of the middle ear bones in these species. Biologically realistic models can be used to investigate the biomechanics of hearing in cetaceans, much of which is currently unknown. In the present study, the elastic moduli of the auditory ossicles (malleus, incus, and stapes) of eight species of cetacean, two baleen whales (mysticete) and six toothed whales (odontocete), were measured using nanoindentation. The two groups of mysticete ossicles overall had lower average elastic moduli (35.2 ± 13.3 GPa and 31.6 ± 6.5 GPa) than the groups of odontocete ossicles (53.3 ± 7.2 GPa to 62.3 ± 4.7 GPa). Interior bone generally had a higher modulus than cortical bone by up to 36%. The effects of freezing and formalin-fixation on elastic modulus were also investigated, although samples were few and no clear trend could be discerned. The high elastic modulus of the ossicles and the differences in the elastic moduli between mysticetes and odontocetes are likely specializations in the bone for underwater hearing.