Wednesday, November 10, 2004

Conflicting Views of Reef-Fish Colors

People can theorize till the cowfish come home about what they see on a reef, but what matters is what fish see, and that's been hard to determine.

Improvements in cameras and in equipment for analyzing light and color are now inspiring new approaches to approximating a fish-eye view of the reefs. Looking at the abundant coloration from a fishy perspective, the new work demonstrates that people can be quite wrong about what's showy and what's subtle.

At the wavelengths in which fish see the world, the yellow of a trumpet fish swimming along 3 meters or more away becomes a "very good match" for the average reef background, says Marshall.

These researchers measured the wavelengths bouncing off various parts of the reef to come up with what they call an average reef color. They found, for example, that a common light-blue color, familiar to fish fanciers in the bands on the blue-and-yellow angelfish Pygoplites diacanthus, matches the general bluish background a fish sees when looking into the distance through relatively deep water.

"What's surprising is that some of the colors that look bright to us are for camouflage," Marshall says.
via Science News

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