Tuesday, March 10, 2009

Cephalopod star

There are a lot of amazing octopus videos around. Here's the most famous camouflage one:


Of course as biologists we want to look a little deeper. The cool bit is that it gets even more amazing as you think about it more closely. As PZ Myers pointed out on his blog, the octopus needs to do four things to achieve this trick:
  1. It needs good visual system. In order to match the background you need to be able to see it. To match it well, you need to see it well.
  2. To pull off the fast change you need a fast connection from the brain to the color changing organ.
  3. Speaking of which, yes, the octopus needs organs that can change color. Cephalopods have tiny, discrete sacs of pigment scattered all over their body, each one ringed with muscles that can close the sac to conceal the pigment, or expand the sac to expose the pigment.
  4. Finally, the octopus needs a set of rules, an algorithm, so it can translate what is sees with its eyes into a visual pattern that hides the animal.
For more information check out the website of Roger Hanlon at Woods Hole Marine Biological Laboratory. The New York Times had a nice article on his lab recently, Revealed: Secrets of the Camouflage Masters. For a more scientific, but still very accessible treatment, see Cephalopod dynamic camouflage, in Current Biology.

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