Tuesday, March 9, 2010

Water Strider

Water Striders have emerged from their winter havens and are once again skating across the calm waters of the creek pools. This is a common insect that can be found skimming the surface of just about any calm body of water. I don’t know of any youngster that doesn’t have a fascination for this little creature.

It has long been known that the water surface tension helps keep the Water Strider from sinking, but it was just a few years ago that the striders legs were found to be lined with overlapping microscopic hairs that trap air bubbles and make a super water repellent covering. This hairy bubble layer is the tool that allows the strider to be so agile on the water. The circles around the striders feet delineate the dimples made by the strider on the water’s surface.

The dimples are most easily observed as shadows on the creek bottom. The Water Strider moves by making a rowing action with the center pair of legs. The leg is like an oar shaft and the dimple plays the part of the blade. When the strider snaps its legs back, the dimple is pushed against the surrounding body of water and the strider moves forward.

The Water Striders are predators that patrol the water looking for anything small enough to capture. The stout front legs are used for grabbing and holding prey. They’re also not shy about taking advantage of any larger animals that may have died on the water. It’s not unusual to find something like a floating minnow carcass that is surrounded by feeding Water Striders.

As a child, I spent many hours hanging over the water trying to grab a Water Strider. My grandfather said they didn’t really exist and therefore, couldn’t be caught. Fortunately, I wasn’t that gullible. I managed to catch several over the years and still enjoy scooping one up for a closer look.


  1. i knew there were other good reasons not the shave my legs!

  2. Anonymous - You must be a petite little thing if you think that will allow you to walk on water.

  3. Steve, have you looked closely at the dimples? They're not smooth at all, but feathered. Zoom in on any of your photos and you'll see. Do you have any idea what's going on?

  4. Anonymous - The feathery effect is the result of image distortion caused by the curved water surface in the dimple. In some cases it's the image of the stream bottom and in others it's the reflection of the strider's legs and other nearby objects. Part of it is also lack of resolution in the photo.

  5. Steve, would you consider making your second photo above available? I'm writing a guide to sag ponds on the San Andreas Fault...

  6. Barbara. You have my permission to use the photo. You can pluck it from the blog or you can provide me with your e-mail address and I will send you the original. Good Luck with your project.