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arXiv · 2510.25520

Octopus-like Reaching Motion: A Perspective Inspired by Whipping

Shengyao Zhang·Yiyuan Zhang·Chenrui Zhang·Yiming Li·Wenci Xin·Yuliang Liufu·Hong Wei Ng·Cecilia Laschi
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Abstract

The stereotypical reaching motion of the octopus arm has drawn growing attention for its efficient control of a highly deformable body. Previous studies suggest that its characteristic bend propagation may share underlying principles with the dynamics of a whip. This work investigates whether whip-like passive dynamics in water can reproduce the kinematic features observed in biological reaching and their similarities and differences. Platform-based whipping tests were performed in water and air while systematically varying material stiffness and driving speed. Image-based quantification revealed that the Ecoflex Gel 2 arm driven at 150 rpm (motor speed) reproduced curvature propagation similar to that observed in octopus reaching. However, its bend-point velocity decreased monotonically rather than exhibiting the biological bell-shaped profile, confirming that the octopus reaching movement is not merely a passive whipping behavior. The absence of propagation in air further highlights the critical role of the surrounding medium in forming octopus-like reaching motion. This study provides a new perspective for understand biological reaching movement, and offers a potential platform for future hydrodynamic research.

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Shengyao Zhang, Yiyuan Zhang, Chenrui Zhang, Yiming Li, Wenci Xin, Yuliang Liufu, Hong Wei Ng, Cecilia Laschi. 2025-10-29. Octopus-like Reaching Motion: A Perspective Inspired by Whipping. https://arxiv.org/abs/2510.25520

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