Tuesday, December 15, 2009

Octopus achievement

As of December 14, 2009, the octopus is officially classified - with humans, primates, birds, dolphins, elephants, and sea otters - as an animal that uses tools. Two Australian researchers have documented the 1st case of tool use in an invertebrate animal and published their account in Current Biology. Although octopuses have been known to make use of available shells for shelter, that is not considered tool use. What the veined octopus (1st photo) does is dig out discarded coconut shells from the ocean floor, clean them of mud with a jet of water, cover one or more with its body, walk along on it "tiptoes," and then use the shells to hide under when necessary. This complex behavior shows the planned future use of the shells - and is also hysterically funny to watch: "We were blown away....It was hard not to laugh underwater and flood your [scuba] mask." Also a surprise is the fact that the tool use is an effort by the octopuses to protect themselves, not to catch food. Researcher Julian Finn has observed the octopuses carrying the coconuts up to 65': "I could tell that the octopus, busy manipulating coconut shells, was up to something, but I never expected it would pick up the stacked shells and run away. It was an extremely comical sight — I have never laughed so hard underwater."

More devious than comical is the behavior of the blanket octopus (2nd photo). Since it is immune to the venom, it rips off a tentacle of the poisonous Portuguese man o' war jellyfish and uses it to defend itself. This species of octopus also protects itself by unfurling a large net-like membrane that spreads out like a cape and increases its apparent size, thereby deterring predators.

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