Keep your eight arms to yourself or you might get face full of silt and shells underwater.
Some female octopuses aren't afraid to repel an unwanted advance by flinging a pile of junk. First-of-its-kind footage shows the creatures propelling silt and shells through the water in the octopus equivalent of a "throw."
"Wild octopuses project various kinds of material through the water in jet-propelled 'throws,' and these throws sometimes hit other octopuses," reads a statement from the University of Sydney Peter Godfrey-Smith and colleagues who authored a study published Wednesday in the journal Plos One.
In a full 24 hours of footage recorded off the coast of Australia in 2015 and 2016 using underwater cameras, the researchers cataloged 102 examples of gloomy octopuses (Octopus tetricus) tossing everything from dirt and debris to the octopus equivalent of table scraps around the sea floor.
In one clip, a female octopus can be seen tossing off a shell after chowing down its contents.
"There is some evidence that some of these throws that hit others are targeted, and play a social role," the authors add.
Somewhat ironically, the octopuses aren't relying so much on any of their eight arms to make these throws. Instead they gather up the material to be tossed and then propel it through the water using their siphon, which is a tube-like part of their anatomy that can eject water at high speed. So it's a little bit like an underwater hydraulic slingshot action rather than a throw the way we might attempt it.
The researchers found that about two-thirds of throws were from females, often tied to interactions with other octopuses coming near or attempting to mate.
Octopuses can sometimes change their coloration, with darker skin colors associated with aggression. The researchers noticed darker individual octopuses threw with more force and were more likely to hit another octopus with their throws. Still, only about 17% of the throws observed actually hit other individual octopuses.
The researchers says more study is needed to try and discern the intent behind this odd aquatic behavior, but it appears octopuses can target other individuals with self-propelled projectiles, something only seen in a few other species besides humans. All the more reason to avoid these suckers -- and their actual suckers.