Monday, November 08, 2010

The same octopus...

The best way to spot an octopus on the reef is by looking out, rather than looking down.  Octopuses like to survey their territory, and when they’re resting they sit on the tops of ledges, outcroppings, etc. in order to see everything around them.  An octopus can see you coming from a long way away, so if you’re swimming along and just looking down into holes in the reef, the octopus’ll be long gone by the time you get there. The best way to find one is to swim slowly and look out at the highest points around you.  When an octopus sees you it’ll usually change color and drop down quickly, immediately giving away its position.  It’s kind of like hide-and-seek, except the octopuses don’t usually want to be found, and rather than laughing or losing gracefully, they just shoot water at you with their siphon. I found this guy in about 5 feet of water at Hanauma Bay yesterday trying to look like a rock.

The same octopus 30 seconds later...

This is the same octopus about 30 seconds later. One of the coolest things about the octopus is its ability to change color.  All Cephalopods can do this, but octopuses are by far the best at it.  They have 4 different tools which they use to change color and brightness, these are Chromatophores, Iridophores, Leucophores, and Bioluminescence, which can be activated as a chemical reaction within the octopus’ skin cells. In basic terms, the octopus possesses all the colors in its skin already.  To change, it reveals certain colors by unfolding microscopic sacks in its skin and keeping others tightly shut.  It’s a very complicated, detailed process that happens in several thousandths of a second. If you want the nitty gritty on it, some great info can be found in this PDF on The Cephalopod Page.

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