Patterns of load distribution among the legs in small water striders during standing and striding

Water striders (Gerris argentatus) move across the water surface by taking advantage of the surface tension, which supports their bodyweight without breaking. During locomotion, the midlegs are primarily responsible for generating thrust, whereas the other legs support the body. Although the aspects of standing and locomotion on the water surface are well understood, relatively fewer studies concerned the coordinated biomechanical movements of the legs. In order to maintain buoyancy of the body on the water surface, the leg positions must be adjusted to distribute the bodyweight appropriately. The present study investigates distribution of the bodyweight on the legs in relatively small water striders. We aimed to understand how loading on the legs changes during sculling that leads to sliding of the body on the water surface. The assistance of all legs at every moment enables the body to maintain its floating during standing and striding. Water striders can achieve a gentle striding through the midlegs driving phase in association with smooth load shifting among their legs, which are positioned in a specific configuration to support the insect on the water surface.