Université de Tours, IRBI UMR CNRS 6035, Parc Grandmont, 37200 Tours, France.
J R Soc Interface. 2010 Feb 6;7(43):343-52. doi: 10.1098/rsif.2009.0210. Epub 2009 Jul 29.
Whirligig beetles (Coleoptera: Gyrinidae) are semi-aquatic insects with a morphology and propulsion system highly adapted to their life at the air-water interface. When swimming on the water surface, beetles are subject to both fluid resistance and wave resistance. The purpose of this study was to analyse swimming speed, leg kinematics and the capillarity waves produced by whirligig beetles on the water surface in a simple environment. Whirligig beetles of the species Gyrinus substriatus were filmed in a large container, with a high-speed camera. Resistance forces were also estimated. These beetles used three types of leg kinematics, differing in the sequence of leg strokes: two for swimming at low speed and one for swimming at high speed. Four main speed patterns were produced by different combinations of these types of leg kinematics, and the minimum speed for the production of surface waves (23 cm s(-1)) corresponded to an upper limit when beetles used low-speed leg kinematics. Each type of leg kinematics produced characteristic capillarity waves, even if the beetles moved at a speed below 23 cm s(-1). Our results indicate that whirligig beetles use low- and high-speed leg kinematics to avoid maximum drag and swim at speed corresponding to low resistances.
水黾（鞘翅目：水黾科）是半水生昆虫，其形态和推进系统高度适应其在气水界面的生活。当在水面游泳时，甲虫受到流体阻力和波浪阻力的共同作用。本研究旨在分析在简单环境下水黾在水面上的游泳速度、腿部运动学和毛细波。使用高速摄像机对 Gyrinus substriatus 水黾在一个大容器中进行拍摄，并估计阻力。这些甲虫使用三种不同的腿部运动学类型，其腿部划动的顺序不同：两种用于低速游泳，一种用于高速游泳。通过不同类型的腿部运动学的组合产生了四种主要的速度模式，并且产生表面波的最小速度（23cm/s）对应于当甲虫使用低速腿部运动学的上限。即使甲虫的移动速度低于 23cm/s，每种类型的腿部运动学也会产生特征性的毛细波。我们的结果表明，水黾使用低高速腿部运动学来避免最大阻力并以对应于低阻力的速度游泳。
