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Mammal Study
Abstract
Abstract.
Studies on odontocetes (e.g., porpoises) have revealed that these animals may adaptively use vision. The present study examined the contributions of vision to the approaching behavior of the harbor porpoise (Phocoena phocoena). When a porpoise approached a target, the time-to-contact perceived by the animal and its trajectory with a visual impediment condition were compared with those in the control (no impediment) condition. The results suggested that approaching behavior to a stationary target was guided by the animal's evaluation of time-to-contact (τ), maintaining the time derivative of τ () at a constant value. A porpoise with visual deprivation exhibited grater τ value and a longer evaluation time before contact than a porpoise that was not blindfolded in the task of reaching for the target. Furthermore, the porpoise with a visual impediment changed its swimming trajectory toward a target less than the control, which appeared to adaptively adjust its approaching trajectory. These findings imply that the use of vision aided echolocation and enables precise control and alteration of the trajectory during the approach. The present study has implications for adaptive use of vision during approaching behavior in the harbor porpoise.
This work was supported by JSPS KAKENHI Grant Number 26450255 to Takashi Matsuishi and by the Graduate Grant Program of the Graduate School of Letters, Hokkaido University to Tomoki Maezawa. This work was supported by Graduate Grant Program of Graduate School of Letters, Hokkaido University to Tomoki Maezawa. We gratefully acknowledge our reviewers for their careful and insightful comments on the paper.
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