How Does a Water Strider Go on the Surface of the Water?

Surface Tension

• Water molecules attract one another, thereby giving water a surface tension, or "skin," which causes water to bead and form droplets. Since the surface of a body of water has this "skin," extremely light objects, with widely distributed weight, can actually rest on the surface of the water without sinking. The size of the water strider and weight distribution given by its long legs allows it to move about on the surface of the water without actually going below the surface.

Just the Right Length

• A water strider's legs are strong but flexible. This is essential to its ability to walk on water rather than just stay in one position on the surface. The legs of the water strider are just long enough to offer maximum flexibility and support the weight of the water strider and still allow movement of its legs but not add extra drag.

Flotation Devices

• The legs of the water strider have microsetae--tiny, invisible hairs, less than 3 micrometers wide. By contrast, a human hair is between 80 and 100 micrometers in diameter. These minuscule hairs have even smaller grooves in them. Air gets trapped in these tiny spaces and forms air bubbles, giving the water strider a cushion of air, helping to keep it above the surface of the water.

Hydrophobic Legs

• The structure of the water striders' legs makes them hydrophobic, or water-repellent. The hydrophobic nature of the legs and the particular speeds at which they move allow them to bounce on the surface of the water, so that they can leap without sinking.

Research

• Research into the ability of the water strider to move on the surface of the water may help scientists to design new waterproof materials and also robots and even crafts that will mimic the ability of the water strider to walk on water without getting wet.