Female Octopuses Throw Silt to Ward off Male Harassers

Female octopuses throw silt to ward off male harassers [Video]

WHAT’S BEING CLAIMED:

  • Female octopuses were found to intentionally throw debris at other octopuses, usually males who try to mate with them.
  • Octopuses have been known to throw debris using their tentacles while den building, but this was the first time that they were observed targeting other octopuses.
  • Scientists observed that the octopuses threw more vigorously when targeting others, and preferred silt over shells.

Female octopuses defend themselves from male harassers by hurling objects at them, according to scientists.

The clever cephalopods have been known to “throw” stuff by placing an object in their tentacles and then propelling it with a jet of water. They have previously been observed doing this while building and cleaning their dens, but this was the first time that they were documented throwing objects at another octopus.

Biologist Peter Godfrey-Smith of the University of Sydney, along with his colleagues, observed a group of common Sydney octopuses in an octopus-rich area called Jervis Bay off the Australian coast back in 2015.

They noticed that some octopuses threw debris at other octopuses. When they returned the next year to collect more footage, they found that some octopuses indeed targeted other octopuses intentionally.

Footage captured in 2016 showed a female octopus gathering projectiles, like silt or shells, to launch at a male octopus who was trying to mate with her. While the male tried to dodge, five out of ten throwing attempts hit him.

  

Godfrey-Smith told New Scientist’s Michael Le Page that the footage convinced him that the attack was intentional.

It also seemed that the octopuses threw more vigorously when targeting others, and preferred silt over shells.

Octopuses usually angle projectiles between their front two tentacles when den-building. But when they target other octopuses, they shoot between tentacles further to right or left. Females tend to use this targeting technique often, and usually at males.

According to the Independent’s Tom Batchelor, only a few creatures, such as elephants and chimps, target members of their own species.

Godfrey-Smith tols New Scientist, “It’s pretty rare. Especially rare is throwing of objects at other members of the same population.”

The Herald Sun‘s Katie Camero reported that around 90 percent of the 101 throws observed in 2015 were done by females. Around 66 percent of the observed throws, whether targeted or not, were made by two particular females.

They observed one female deviate from the usual water-propelled projectile attack by throwing a shell frisbee-style with its tentacles.

Male octopuses were sometimes seen raising their tentacles in anticipation, but they didn’t retaliate.

The study, which is yet to be peer-reviewed, was published in August on the preprint server bioRxiv.

 

Source: Smithsonian Magazine

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