Squid are typically solitary and not exactly neighborly when other cephalopods encroach on their personal space, even if it means weaponizing almost anything within reach.
In a recently published study by a team of researchers in Australia, the US and Canada, observations of wild squid throwing shells and sand directly at other members of the same species have raised the question of whether this unusual behavior is a deliberately antisocial act — or whether passers-by accidentally get caught up in it the line of fire.
Scientists first observed octopuses hurling objects at each other in a scene of apparently heated argy-bargy off the east coast of Australia in 2015, where such large numbers of Sydney octopuses (octopus tetricus) gather, which have baptized scientists of the Octopolis region.
Now, in a newly published study, they’ve found that the flingers are predominantly female — and they’re probably trying, at least in some cases, to ward off overly infatuated males.
“Throwing material by wild squid is common at both of our study sites. These throws are achieved by collecting and holding material in the arms and then expelling it under pressure,” the researchers write.
“There were 90 litters by females and 11 by males, a ratio of 8.9:1.”
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Many animals throw debris at others, and there are many reasons for this. It may be threatening, defensive, or related to catching prey. However, most animals that are observed throwing things in ways other than their own.
To find out why octopuses pelt shells, silt and algae, a team of researchers led by University of Sydney philosopher of science Peter Godfrey-Smith set out to watch cocking in action.
Using non-invasive GoPro cameras left on site, they recorded over 100 instances of Octopolis residents hurling debris at random. The squid would hold material in their arms and then use their siphons to blast a jet of water that would blow the material up to several body lengths away.
When they analyzed their recordings, the researchers found that there appeared to be two main types of tossing. The first had to do with housekeeping and keeping their cozy dens free of unwanted waste and leftovers.
The second seemed a bit more purposeful. Octopuses, which were (mostly) female, have been observed to throw material at other octopuses during targeted attacks. Overall, grenades were the most thrown object with 55 recorded cases.
On 33 percent of these aimed throws, the thrown object actually hit the intended target, with silt being the best material for the task. The targets were either other nearby females or males attempting to mate.
In a notable case recorded in 2016, a female octopus threw material at a male 10 times over a period of 3 hours and 40 minutes, hitting him five times. Interestingly, squid struck by such ejections made no attempt to retaliate, but sometimes attempted to duck (though not always successfully).
Another, perhaps more controversial, explanation for this behavior might be that the throws are not always necessarily aimed, but could be a form of tantrum due to frustration.
After several dramatic interactions, the researchers observed one octopus throwing things in a way that didn’t appear to be aimed at the other octopus. However, because it’s difficult to ascribe intentions to animals, especially ones as alien as squid, it’s impossible to definitively conclude that this is the case.
Anyway, it seems that throwing seems to play some sort of social role.
“Octopuses can therefore definitely be included in the shortlist of animals that regularly throw or propel objects, and tentatively included in the shorter list of those that direct their throws at other animals,” the researchers write.
“When they’re actually targeted, these throws are aimed at members of the same demographic in social interactions — the least common form of non-human throwing.”
This study was published in Plus one.
A previous version of this article was published in August 2021 when the study was in the preprint stage.