Characterisation of whisker control in the California sea lion (Zalophus californianus) during a complex, dynamic sensorimotor task
Studies in pinniped whisker use have shown that their whiskers are extremely sensitive to tactile and hydrodynamic signals. While pinnipeds position their whiskers on to objects and have some control over their whisker protractions, it has always been thought that head movements are more responsible for whisker positioning than the movement of the whiskers themselves. This study uses ball balancing, a dynamic sensorimotor skill that is often used in human and robotic coordination studies, to promote sea lion whisker movements during the task. For the first time, using tracked video footage, we show that sea lion whisker movements respond quickly (26.70 ms) and mirror the movement of the ball, much more so than the head. We show that whisker asymmetry and spread are both altered to help sense and control the ball during balancing. We believe that by designing more dynamic sensorimotor tasks we can start to characterise the active nature of this specialised sensory system in pinnipeds.
KeywordsActive touch Vibrissal Pinniped Sensing Haptics
The authors would like to thank all the staff at Blackpool Zoo for their full co-operation and assistance, especially Alex Kidd (sea lion Trainer), who was the secondary trainer throughout the project. We are also grateful for the support from the Division of Biology and Conservation Ecology at Manchester Metropolitan University throughout the study.
All experiments comply with UK regulations and were approved by ethics committees at both Manchester Metropolitan University and Blackpool Zoo.
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