近日，哈佛大学Mahadevan, L.团队研究了蛇类快速非平面步态的拓扑动力学。2025年4月10日，《自然—物理学》杂志发表了这一成果。

蛇表现出多种多样的步态，包括在空中滑翔和在陆地上侧身，其中特别值得注意的是它的平面外运动。研究组报告了另一种非平面步态的观察，主题是幼年水蟒（Eunectes notaethem）从威胁环境中逃生的策略，因其形状，课题组将其称为S-start。在这种短暂的运动模式中，蛇扭动和弯曲出平面，同时在其中部向前滚动而不打滑。

为了量化该观察结果，该团队开发了一个与摩擦衬底各向异性相互作用的有源非平面灯丝模型。课题组研究人员证明了运动是由于一个拓扑量的局部脉冲的传播-链路密度。以体重和微转矩为特征的二维相空间表明，相对较轻的幼鱼能够进行s型启动，而较重的成年鱼则不能，这与实验结果一致。该团队还表明，周期性的s -start序列自然会导致侧绕步态。

附：英文原文

Title: Topological dynamics of rapid non-planar gaits in slithering snakes

Author: Charles, N., Chelakkot, R., Gazzola, M., Young, B., Mahadevan, L.

Issue&Volume: 2025-04-10

Abstract: Snakes exhibit a wide variety of gaits, including gliding in air and sidewinding on land, which is particularly notable for its out-of-plane motion. Here we report the observation of another non-planar gait used as an escape strategy from threatening situations by juvenile anacondas (Eunectes notaeus), which we refer to as the S-start due to its shape. In this transient mode of locomotion, the snake writhes and bends out of the plane while rolling forward about its midsection without slippage. To quantify our observations, we develop a model for an active non-planar filament that interacts anisotropically with a frictional substrate. We demonstrate that locomotion is due to a propagating localized pulse of a topological quantity—the link density. A two-dimensional phase space characterized by scaled body weight and muscular torque shows that relatively light juveniles are capable of S-starts, whereas heavy adults are not, consistent with our experiments. We also show that a periodic sequence of S-starts naturally leads to a sidewinding gait.

DOI: 10.1038/s41567-025-02835-7

Source: https://www.nature.com/articles/s41567-025-02835-7