- Kids do it. Dogs do it. And now marine
biologists know that even octopuses play, making them the only invertebrates
-- animals without spines -- known to exhibit playful behavior.
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- The findings contradict a decades-old
belief that only mammals and birds like cats, dolphins, parrots and people
play, says Seattle Aquarium biologist Roland C. Anderson in a paper accepted
for publication later this year in the Journal of Comparative Psychology.
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- Octopuses are considered the smartest
of the invertebrate family, much brighter than their oyster, snail and
clam cousins, Anderson says. In his study, he defines play as randomly
repeating an activity that has no immediate benefit to the animal.
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- Studying how octopuses play may help
scientists understand their behavior and how they survive, says Jean Geary
Boal of the University of Texas Marine Biomedical Institute.
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- Anderson found that two of eight octopuses
studied showed playful behavior by squirting streams of water though their
breathing funnel at empty plastic bottles floating in their tanks, pushing
them into a current of water and allowing them to float back before squirting
them again. "A marine parallel to bouncing a ball," Anderson
describes in his paper.
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- The other six octopuses simply fondled
the bottles and lost interest. "They are just like people,"
Anderson says. "Some play and some don't."
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- That may have to do with their personalities,
says Anderson, who describes the 2-year-old octopus Ursula, a former Seattle
Aquarium resident, as aggressive. Larger, older octopuses tend to be more
sedate, Anderson says. "They're big pussycats."
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- Unlike kids and dogs, who might giggle
or bark during play, Anderson says it's difficult to know whether octopuses
enjoy playing. "It's hard to tell their emotions," he says, although
changes in their color might be an indicator.
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- Some octopuses turn bright red in a feeling
usually attributed to anger, and can change to white, which is attributed
to fear. So if they encounter a predator, their flesh might pale, he
says, like a person caught in a scary situation.
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- Do octopuses make good playmates? "Sort
of," Anderson says. "You don't get a lot of response from octopuses.
They don't come up and lick you."
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