The effects of visual impediment on the approaching behavior of harbor porpoise, Phocoena phocoena

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 th...

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Bibliographic Details
Published in:Mammal Study
Main Authors: Maezawa, Tomoki, Matsuishi, Takashi, Ito, Kiyohide, Kaji, Seiichi, Tsunokawa, Masatoshi, Kawahara, Jun I
Format: Article in Journal/Newspaper
Language:English
Published: 日本哺乳類学会(The Mammal Society of Japan.)
Subjects:
480
Online Access:http://hdl.handle.net/2115/78809
https://doi.org/10.3106/ms2019-0012
Description
Summary: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 (tau), maintaining the time derivative of tau ((tau) Over dot) at a constant value. A porpoise with visual deprivation exhibited grater (tau) Over dot) 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.