Optics at the creek

At the bottom of a canyon, the clear, cold waters of a creek make their way noiselessly to the Pacific. The heat of the warm spring day hasn't yet reached through the canopy of big-leaf maple trees. Over the surface of the stream, a tiny gnat that didn't stretch properly before flight pulls a wing muscle and shortly thereafter tumbles into a sunlit patch of water. Because live gnats don't sink, but do have some parts that "wet" with water, the gnat becomes trapped on the water surface and can't fly off. A water strider, Gerris lacustris, senses the ripples generated by the struggling insect, skates over, and has lunch.

Access to the full text of this article is restricted. In order to view this article please log in.

Add a Comment