Invisible Fish

November 27, 2015

BOB HIRSHON (host):

Fish camouflage. I’m Bob Hirshon and this is Science Update.

The open ocean doesn’t provide many places to hide. Underwater, light is polarized—meaning light waves travel in the same plane—and many fish spot prey by detecting variations in polarized light. But University of Texas at Austin biologist Molly Cummings reports in the journal Science that some fish have evolved specialized skin cells that reflect polarized light, camouflaging them.

MOLLY CUMMINGS (University of Texas at Austin):

That suggests that natural selection is shaping the reflectance properties of these fish to minimize their detectability under viewing angles for survival.

HIRSHON:

Using a camera that detects polarized light, Cummings found that the fish were particularly disguised when viewed from angles by which predators normally approach. The discovery could inform better military strategies for hiding in open water. I’m Bob Hirshon, for AAAS, the science society.

103678_web — Researchers from FAU’s Harbor Branch and collaborators collected more than 1,500 video-polarimetry measurements from live fish from distinct habitats under a variety of viewing conditions, and have revealed for the first time that fish have an “omnidirectional” solution they use to camouflage themselves, demonstrating a new form of camouflage in nature — light polarization matching. The top panel in black/white shows the intensity and the two other panels resolve different aspects of polarized light scattered off the fish. (FAU Harbor Branch Oceanographic Institute)