Kinematic analyses of turning maneuvers in vertically climbing geckos

Turning is instrumental for animal survival and ecological adaptation, particularly in predator–prey interactions. Geckos (Gekko gecko) are exceptional climbers and have been widely studied for their kinematics and biomechanics, especially in bioinspired robotics. However, the mechanisms underlying turning maneuvers on vertical surfaces remain poorly understood. In this study, we investigated the turning kinematics of geckos during 90° vertical climbs using an optical motion capture system. Marker coordinates of body joints were collected from five individuals. The geckos employed a diagonal couplet sequence in this process and climbed at 0.46 SVL s-1. Analysis of trunk-limb coordination strategies revealed the adaptability of geckos in adjusting postures, including body position, to successfully execute turns. Specifically, the animal's trunk and tail moved in opposite phases despite its tail swing remaining on one side of the body axis. Compared to straight vertical climbing, geckos increased their duty cycle, left-side lateral spread distance, and single leg span while reducing the right forelimb's single leg span to complete the turn. These findings not only enhance our understanding of turning patterns in climbing animals but also provide valuable insights for developing legged climbing robots with improved high-performance gaits.