Octopuses Living In Close Quarters May Be Throwing Shells At Each Other—On Purpose

Claustrophobic conditions might be making Gloomy Octopuses contentious.

Peter Godfrey-Smith, a marine biologist at the Graduate Center, City University of New York, presented video evidence at the Behaviour2015 conference in Cairns, Australia this month demonstrating a new and strange tendency in Octopus tetricus, nicknamed the Gloomy Octopus. In Jervis Bay, Australia, octopuses living on a bed of shells in close proximity were seen gathering up shells and ocean debris in their eight arms and throwing it at each other. Octopuses have tubular openings on the sides of their bodies that they use for jet propulsion; Godfrey-Smith’s observation, though, suggests that they’ve found another use for them.

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The Gloomy Octopus. Note the gloomy eye.

Here’s Sandhya Sekar, writing for New Scientist:

“In the ‘throwing’ behaviour, it gathers up a pile of stuff in its arms, and then directs the jet under the web of its arms, and throws out all the stuff under pressure,” says Godfrey-Smith. “So it’s a throw rather than a spit, though the throw uses water pressure—it uses a sort of inverted jet propulsion.”

Godfrey-Smith is not yet certain that the behaviour is intentional. It may just be a case of enthusiastic housekeeping showering the neighbours with debris.

If the behavior is in fact intentional, it’d be an anomaly in the animal kingdom—we don’t often see species (other than humans) throwing things. The researchers say the octopuses are being hit by debris more often than expected, so it’s possible that this swift maneuver isn’t just meant to clean out their homes or ward off tiny fish. With little personal space and few other nesting spots, these cephalopods could be getting a little antsy in their cramped habitats.

Watch the scientist's footage of octopuses fighting.