| MadSci Network: Zoology |
Hello Fredrik, I know that your question was already answered by "OceanLink - A Marine Science Information and Interaction Web Site," but I thought it would be useful to post the response on the Mad Scientist for the benefit of visitors here.
The following response was posted by an unspecified Marine Scientist at the following site: : http://oceanlink.island.net/index.html The color change phenomenon seen in octopus and other cephalopods is one of the more fascinating in nature. The reaction that takes place is not chemical in nature. The skin of an octopus contains many pigment cells, or "chromatophores". These chromatophores may be one of several colors: yellow, orange, red, blue or black. Each chromatophore is only one color. The chromatophores may be individually expanded or contracted - this process is under the control of the nervous system, and perhaps hormones. The expansion and contraction of chromatophores is accomplished with tiny muscles attached to the outside of the cells. When the muscles are contracted, the pigment in the cell is pulled out into a flat plate, and the color in the cell is displayed. When the muscles are relaxed, the cell and color concentrate into a small, hard to see dot. By expanding and contracting different chromatophores of different colors, the animal can change its external appearance. Because the chromatophores are under neural control, color changes can be accomplished very rapidly. Regards, Justin Remais Engineering Assistant, Lawrence Berkeley National Laboratory
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