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Hairy legs and very small hairs on a strider's body
(as for vast majority of insects and plants),
allow striders to freely move and jump on the water surface.
Have you ever wondered how water strider is able to move, glide, and even jump on the water surface? And there are good reasons to wonder. Conventionally, it is thought that it is wax on the body of water strider that gives him the floatability and mobility. However, the best water-repellent substances (similar to organic oils or waxes) cannot nearly account for that.
Close investigation shows that hairy legs, and very small hairs on strider’s body are in fact responsible for its remarkable floatability and water-repellent properties. This is a vivid manifestation of Cassie’s law for surface wettability of heterogeneous materials. In fact, presence of small hairs is universal for insects and many plants' leaves. It is plausible that Nature used this mechanism to repel ubiquitous water and protect insects and leaves from infestation and rotting. Future generations of smart small floating devices will most likely use similar phenomena to move on the water surface.
Reporters may freely use this image. Credit: Terry Tuk, Julie Macdonald, Igor Kliakhandler (2010).