Endpoints; May 2001; Scientific American Magazine; by Staff Editors; 1 Page(s)

Ellen J. Prager, assistant dean of the University of Miami's Rosensteil School of Marine and Atmospheric Science and author of The Oceans (McGraw-Hill, 2000), offers this explanation: A number of cephalopods-the group of animals that includes octopuses, squid and cuttlefish-are skilled in the art of color change, which can be used for camouflage or to startle and warn potential predators in their undersea realm. Many of these creatures have special pigment cells called chromatophores in their skin. By controlling the size of the cells, they can vary their color and even create changing patterns. Chromatophores are connected to the nervous system, and their size is determined by muscular contractions. The cephalopods also have extremely well developed eyes, which are believed to detect both the color and intensity of light. Using their excellent eyesight and chromatophores, cephalopods camouflage themselves by creating color patterns that closely match the underlying seafloor. In squid, color changes also occur when the animal is disturbed or feels threatened.

In addition to color control, many squid can produce light and control its intensity. Some marine creatures are believed to use bioluminescence to confuse predators, others may stun their prey, and some use it as a decoy to facilitate escape or as a lure to attract the unwary. It may also offer a means of communication in the dim midwater or twilight region of the sea.