The octopus is one of the iconic denizens of the waters off Greece and many other areas of the world. Known for being very intelligent, the creatures often respond to the world around them by changing color and shape in an effort to defend themselves.
Some, such as those living at the Tampa Bay Aquarium, even routinely paint, apparently as a way to relive the everyday stresses of dealing with other octopuses.
Now, scientists have proven that the multitalented cephalopods can use tools in a different way, often throwing things at each other when they feel threatened or offended.
At least the females do.
Scientists at the University of Sydney in Australia discovered back in 2015 that octopuses could throw, or project, silt away from their bodies as a way to get it away from them.
Using jets of water that they can also employ as a way to propel themselves, the creatures can use these streams to project objects away from themselves.
Biologist Peter Godfrey-Smith returned recently to the same waters only to observe a much more violent behavior that amounted to females — and it was almost always females — throwing shells and other objects directly at other octopuses.
In an area called Jervis Bay which is home to many octopuses, his team observed the them launch objects and sediment as far as several body lengths away; not only that but female octopuses “threw” objects at males when they were feeling harassed.
As soon as what they deem to be an annoying male enters the area, a female octopus will gather projectiles such as shells or silt, using her tentacles to hold them in place before launching the debris toward the offender with a siphon of water.
Although researchers had already witnessed the cephalopods use such a throwing technique in making their dens, this is the first time it had been documented as part of a targeted attack on another octopus.
Although the scientists term the behavior “throwing,” the cephalopods usually place an object carefully in their tentacles and propel it from the back with a jet of water, targeting the jet in a specific direction, toward the offending octopus — who is almost always a male.
The scientific paper written by Godfrey-Smith’s team shows what they had suspected over the recent years, that octopuses intentionally target others when releasing their projectiles.
Once in 2016, a female octopus was observed throwing silt at a male who was attempting to mate with her against her wishes. She did this a total of ten times, connecting with him successfully on five of those attempts.
The male occasionally attempted to dodge the sediment but was only successful about half of the time, according to a report from Newsweek. The team observed that this octopuses throw with particular strength when targeting others — as opposed to when they are clearing out a new den — and they prefer to launch silt instead of seashells.
“That sequence was one of the ones that convinced me (it was intentional),” Godfrey-Smith told interviewers from New Scientist.
When octopuses cast out silt during den-building, the object is normally angled between their front two tentacles. But amazingly, the team noticed that when octopuses shot objects toward others of their species, they held them between tentacles located further to the right or left.
Intriguingly, they discovered that females used this specific targeting technique most times — and usually with males that were attempting to mate with them.
“Some throws appear to be targeted on other individuals and play a social role, as suggested by several kinds of evidence,” the researchers wrote in their paper.
“Such throws were significantly more vigorous and more often used silt, rather than shells or algae…some throws were directed differently from beneath the arms, and such throws were significantly more likely to hit other octopuses.”
Throwing objects at all is quite rare among the members of the animal world. Apart from homo sapiens, our fellow primates the chimps — along with elephants — are known to throw things at each other.
“It’s pretty rare. Especially rare is throwing of objects at other members of the same population,” says Godfrey-Smith in New Scientist.
Incredibly, he and his team under Jervis Bay directly observed a total of 101 throws in 2015, and the vast majority — approximately 90 percent — of those were from females. And some females were more pugnacious than others, with two particular octopuses responsible for approximately 66 percent of throws.
Although most octopuses used the water-spurting technique in their throws, one female amazingly threw a shell like a Frisbee, using her tentacles. Perhaps most intriguingly of all, male octopuses never reciprocated any attack, although they did at times raise their tentacles in a defensive fashion.
“Throwing in general is more often seen by females, and we have seen only one hit (a marginal one) from a throw by a male,” the researchers said. “Octopuses who were hit included other females in nearby dens, and males who have been attempting mating with a female thrower.”
The researchers’ video also showed a female octopus throwing an impressive seventeen times in a period of sixty minutes. Nine of these actions actually resulted in hitting her fellow octopuses, and of these “Eight were hits on a nearby likely female and one was a hit on the most active male.”
Back in December of 2016 Godfrey-Smith directly observed a female octopus targeting a male octopus whom he knew had previously attempted to mate with her. The paper, in recounting this particular episode, said “In one hit, the female’s preparatory motions included a turn toward the male, and the material was emitted between arms R1/R2, bringing the male directly into the path of the throw.
“This sequence is also notable for the behaviors of the male who was the apparent target of the hits.”
Not once did the the researchers witness an octopus which had been hit even attempt to return fire at the thrower — although a good many octopus arms were raised in anticipation of the debris coming their way.
“Octopuses can thus definitely be added to the shortlist of animals who regularly throw or propel objects, and provisionally added to the shorter list of those who direct their throws on other animals,” Godfrey-Smith and the other researchers wrote in their paper.
“If they are indeed targeted, these throws are directed at individuals of the same population in social interactions — the least common form of nonhuman throwing.”