How do water striders stay on top of the water’s surface?

Water striders (family Gerridae) are able to stay on top of the water because they are supported by the surface tension of the water, which acts like a stretched, elastic membrane.12

Several physical adaptations allow these insects to utilize this phenomenon:

• Body Structure: Water striders have small, slender bodies with very little bulk, making them light enough to be supported by the surface film.1
• Leg Distribution: Their long, thin middle and hind legs spread their weight across a wider area, causing only a slight indentation in the surface film rather than breaking through it.1
• Water-Repellent Hairs: The feet (tarsi) and the body are covered in a fine, dense, water-repellent (hydrofuge) pile. This layer of hair traps air, which prevents the insect's body from becoming wet and sinking, ensuring it remains buoyed by the surface tension.13

While the middle legs are primarily used for propulsion and the hind legs for steering, the front legs are shorter and are typically used for capturing prey or resting on the surface.13