I am fascinated by water striders. These insects are uniquely adapted for their life on the surface of the water. I filmed several of them in a creek. You can’t really see the actual insects very well in the video below, but you can see two things that give away their presence.
The first is that each insect generates two small round shadows and a larger round shadow on the surface of the water. These shadows are created by the way light is altered by the bending of the surface of the water by the strider’s rear (small shadows) and front (large shadow) legs. These insects exploit the surface tension of water to stay afloat coupled with adaptions in the tips of their legs that make the legs water repellent and also help them trap little bubbles of air resulting in high buoyancy.
The second is that these insects use their middle legs as oars generating an explosive movement that propels them forward giving rise to waves that radiate from the strider in a concentric pattern. A multitude of striders in one place can create quite a display of circular waves giving rise to cool interference patterns as shown in the video.