Encore - Water Strider Art

March 21, 2020

Strider Art

Today and every Saturday Earth Science Picture of the Day invites you to rediscover favorites from the past. Saturday posts feature an EPOD that was chosen by viewers like you in our monthly Viewers' Choice polls. Join us as we look back at these intriguing and captivating images.

Photographer: Tommy Hornbeck
Summary AuthorTommy Hornbeck

June 2014 Viewer's ChoiceA Gerridae with a penchant for physics demonstrates a two-point source interference pattern on a fluid surface. Gerridae are commonly called names such as water striders, water skeeters, water bugs and Jesus bugs because of their ability to walk on water. They're covered with hydrophobic micro hairs, repelling water, thus preventing them from being weighed down by splashed water droplets. Their two front legs capture and hold prey; the second pair propel the strider over the water as oars, while the third pair act as rudders. Their water-walking skills are made possible by the surface tension of water molecules that have a greater attraction to one another than to the molecules of the air, giving the water, in effect, an elastic membrane upon which the Gerridae walk. The strider’s forward walking motion sets up twin circular, traveling waves on the water's surface which expand and meet. Where they meet, the peaks and troughs (anti-nodes) create the lovely interference pattern shown above. Photo taken on a pond in western Missouri on May 2, 2014.

Photo Details: Nikon D7100 camera; 1/640 sec. exposure; f/6.3; ISO 400; 85 mm lens.