Are octopuses deliberately throwing things at each other?

AILSA CHANG, HOST:

Anyone who was glued to the World Series will know how important throwing things is to human life. What's the game without a pitch, right? But only a handful of animals are known to chuck objects, like elephants, polar bears and a few primates.

ELISSA NADWORNY, HOST:

Well, scientists recently added octopuses to that list.

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PETER GODFREY-SMITH: An octopus seemed to sort of drop a bunch of shells on another octopus, and we spent a long while watching that tape, trying to work out if it was deliberate or if it was just accidental.

NADWORNY: Peter Godfrey-Smith of the University of Sydney says they needed more evidence, so he and his colleagues set up GoPro cameras underwater at a site off Australia's coast teeming with the so-called gloomy octopus.

GODFREY-SMITH: It's a scallop bed. It's like a sort of endless seafood buffet for them.

CHANG: It's also unusual because Godfrey-Smith says many octopuses tend to be loners, whereas the ones there interact quite a bit.

GODFREY-SMITH: Sort of very low-key wrestling, arm pokes and things like that.

CHANG: And in the videos they captured, you can see magnificently camouflaged octopuses slowly rise up out of a bed of scallop shells and then fling debris through the water. They captured more than a hundred instances.

GODFREY-SMITH: And we began to see these more dramatic cases, where an octopus will gather a bunch of stuff in its arms, sometimes move a little bit forward and then sort of blast out the material, releasing it from the arms and applying pressure from the jet propulsion device that they have.

NADWORNY: So technically, more of a blast than a throw. But after studying the behavior in more detail, they say the octopuses did appear to aim at others, and those in the line of fire sometimes ducked or raised their arms. The results are in the journal PLOS One.

CHANG: Godfrey-Smith points out that this doesn't mean the creatures are warlike.

GODFREY-SMITH: We shouldn't map it too straightforwardly onto the area of human conflict, human relationships. Octopuses are just doing their own weird thing. It's different from what we do.

CHANG: Although the octopuses did throw things at the scientists' cameras a few times. So, you know, like some humans, perhaps the octopuses weren't too fond of the paparazzi.

(SOUNDBITE OF PHARRELL'S "NUMBER ONE (INSTRUMENTAL)") Transcript provided by NPR, Copyright NPR.