Octopuses seen hurling debris at each other

By Candice Marshall 14 November 2022
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A female octopus has been filmed repeatedly launching silt at a male trying to mate with her, with the male frequently ducking to avoid being hit.

“In some cases, the target octopus raised an arm up between itself and the thrower, just before the throw, perhaps in recognition of the imminent act,” says Professor Peter Godfrey-Smith from the University of Sydney’s School of History and Philosophy of Science and Charles Perkins Centre.

The scene is just one of many showing wild octopuses throwing silt, shells and algae, observed as part of a research project, led by Peter.

The team observed common Sydney octopuses (Octopus tetricus) at a marine reserve in Jervis Bay, New South Wales, coming away with over 20 hours of footage to analyse.

Some octopus can be seen hurling the remains of their meals and other materials to clean their dens. In two cases, the debris struck nearby fish.

The video recordings also showed that while both sexes throw debris, the females do it more often than their male counterparts.

See the incredible footage for yourself:

Video credit: University of Sydney

Is it really ‘throwing’?

“It is,” says Peter, “but not in a human sense.”

“Octopuses throw by gathering material in their arms, holding it in their arm web, and propelling it using their siphon – a funnel next to their head – sometimes several body-lengths away.”

Whether this ‘throwing’ action is out of aggression or not also remains unknown.

“It is tempered by the fact that there are some things we have not seen. We have not seen an octopus who was hit by a throw ‘return fire’ and throw back.

“I’d speculate that a lot of the targeted throws are more like an attempt to establish some ‘personal space’, but this is a speculation, it’s very hard to know what their goals might be.”

An illustration shows the mechanics of throwing behaviour. Image credit: Rebecca Gelernter, University of Sydney

The exclusive club

Octopus now join a very small group of animal species known to engage in throwing behaviour. Other species include primates, birds, elephants, and mongoose.

This adds further insight into the intelligence of these previously under-studied creatures.

“[They are” the closest we will come to meeting an intelligent alien,” says Peter.

The research has been published in the journal PLOS ONE.

Related: Caught on film: octopus couple tango to two very different tunes