Like all mammals, toothed whales possess an outer, middle, and inner ear, all of which present major evolutionary adaptations to underwater hearing. Moreover, the development of acoustical fat bodies, which collect and propagate sound waves to the middle ear, has created alternative acoustic pathways that bypass the external ear canal. As such, the external ear canal lost its original function and was long considered to be a vestigial remnant. However, the canal presents many active components, which would indicate a certain function. Up to date, such function is unknown, and even basic knowledge on the morphology of the external ear canal and its associated tissue is largely unknown. Here, we describe the general morphology of the external ear canal in toothed whales, derived from a variety of species. We highlight several structures that are likely to have major implications on its function, including the shape and size of the lumen, the glandular structures, the vascularization and innervation, the muscles, the cartilage and other soft tissues, and as such, provide basic morphological knowledge that is essential for understanding the function of the external ear canal in toothed whales.
Copyright (2020) Acoustical Society of America. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the Acoustical Society of America. The following article appeared in De Vreese, S., André, M., & Mazzariol, S. (2019). Morphology of the external ear canal in toothed whales. Proceedings of Meetings on Acoustics, 37(1), 10016. https://doi.org/10.1121/2.0001281 and may be found at https://asa.scitation.org/doi/abs/10.1121/2.0001281.
