ISSN: 2476-2490
Authors: Tsur I*, Shaviv N and Werner YL
The survival of biological organisms depends upon their ability to nourish, reproduce and find shelter. Nourishment for a predator depends on finding prey. In the absence of sight (e.g., underwater; at night), sound has been evolutionarily favored as a means of remote-detecting prey. This may include echolocation, resembling the man-made sonar under water, turning a mute prey into a sounding object. Cetaceans (dolphins and whales) use acoustic cues, including active sounding in the ultrasonic range, to determine the locations and identities of environmental stimuli in their underwater habitats. Dolphins (Odontoceti) have evolved unique auditory systems for spatially differentiating ultrasonic signals. The aim of this paper is to find out whether directional asymmetry that may support location exists in the dolphin middle ear, and if so, whether it is age or sex linked. We measured the auditory ossicles of 34 pairs of the peripheral hearing organ of Globicephala macrorhynchus: On both sides, the weights and lengths of each of the three ossicles, the area of the stapes footplate, and the angle between incus and stapes; and computed a ratio between ossicle mass and stapedial footplate area. The left-side ossicles were on average heavier, and the angle between the incus and stapes greater in the left ear. We found no significant age- or sex-linked differences with respect to these asymmetries. We propose how the asymmetries may help the animal locate its prey, especially in the vertical plane.
Keywords: Cetacea; Feeding; Middle Ear; Odontoceti; Ossicle Asymmetry; Radar; Sound Location
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