This is the first time that octopuses have been seen throwing things.
Although it is difficult to determine the intent of octopuses propelling debris through the water, the observed behaviours suggest that, at least in some social contexts, octopuses are capable of targeted throws towards other individuals, a behaviour only previously observed in a small number of non-human animals.
According to a study led by Peter Godfrey-Smith at the University of Sydney and colleagues and published on November 9 in the open-access journal PLOS ONE, octopuses appear to actively hurl trash, sometimes in the direction of other octopuses.
Using underwater video cameras, researchers observed the gloomy octopuses (Octopus tetricus) at Jervis Bay, Australia in 2015 and 2016.
Although individual identification was not always possible, they were able to find 102 instances of debris throwing in a group of about 10 octopuses after studying 24 hours of video over many days.
Octopuses gathered material such as dirt or shells and released it by propelling it between their arms and through the water with a jet of water from their syphon (a tube-shaped device that can discharge water at high speeds).
Octopuses had to adjust their syphon into an unusual posture to conduct the throws, implying that the behaviour was purposeful.
Although both sexes were seen throwing, 66% of throws were made by women.
Approximately half of the throws happened during or near encounters with other octopuses, such as arm probes or mating efforts, and approximately 17% of throws hit other octopuses.
Octopuses can vary their skin colour, and dark colours are often linked with aggression. The researchers discovered that dark-colored individuals threw more strongly and were more likely to hit another octopus.
Octopuses hit by thrown material frequently changed their behaviour by ducking or lifting their arms at the thrower.
This is the first time that octopuses have been seen throwing things.
Although it is difficult to determine the intent of octopuses propelling debris through the water, the observed behaviours suggest that, at least in some social contexts, octopuses are capable of targeted throws towards other individuals, a behaviour only previously observed in a small number of non-human animals.
“Wild octopuses project various kinds of material through the water in jet-propelled ‘throws,’ and these throws sometimes hit other octopuses. There is some evidence that some of these throws that hit others are targeted, and play a social role,” the authors wrote.
Image/Videos credit: Godfrey-Smith et al., 2022, PLOS ONE, CC-BY 4.0
Source: PLOS ONE