by Panel A — Octopus (left) projects mud and algae into the water. B – an octopus (right) is struck by a cloud of mud projected into the water by a flying octopus. C – shells, mud, algae or some mixture is held in the arms in preparation for the cast, the mantle inflates in preparation for aeration during the cast, the siphon at this stage may still be visible in its usual position projecting from the gill slit above arm crown? D – the siphon descends over the trailing arm and under the mast and crown of the arm between the trailing pair of arms (arms R4 and L4) and water is forced out through the siphon, by mantle contraction, as trapped debris is released , protruding debris through the water column. Illustrated by Rebecca Gelernter. Credit: Godfrey-Smith et al., 2022, PLOS ONE, CC-BY 4.0 (creativecommons.org/licenses/by/4.0/)
Octopuses appear to intentionally drop debris, sometimes directed at other octopuses, according to a study published Nov. 9 in the open-access journal PLOS ONE led by Peter Godfrey-Smith at the University of Sydney and colleagues.
Researchers recorded the behavior of dusky octopuses (Octopus tetricus) in Australia’s Jervis Bay in 2015 and 2016 using underwater video cameras. They analyzed 24 hours of footage over several days and identified 102 instances of debris dropping in a group of about 10 octopuses, although individual identification was not always possible.
Octopuses collected material such as mud or shells and released it while using a jet of water from their siphon (a tube-shaped structure that can shoot water at speed) to propel it between their arms and through the water, often dropping material many bodies away. To perform the throws, the octopuses had to move their siphon to an unusual position, suggesting that the behavior was intentional.
Throws were observed in both sexes, but 66% of the throws were made by females. About half of the throws were made during or during interactions with other octopuses, such as arm probes or mating attempts, and about 17% of the throws hit other octopuses.
Octopuses can change their skin color, with dark colors generally associated with aggression, and researchers found that dark-skinned individuals tended to throw harder and were more likely to hit another octopus. Octopuses struck by thrown material often changed their behavior by ducking or raising their arms in the direction of the thrower.
This is the first time that throwing behavior has been reported in octopuses. The authors say that while it is difficult to determine the intent of octopuses that propel debris through the water, the behaviors observed suggest that at least in some social contexts, octopuses are capable of targeted throws toward other individuals, a behavior that has been observed only in the past in a few non-human animals.
The authors add, “Wild octopuses project various types of material through the water in jet ‘throws,’ and these throws sometimes hit other octopuses. There is some evidence that some of these throws that hit others are targeted and they play a social role.”
More information:
In the line of fire: Dropping debris from wild octopuses, PLoS ONE (2022). DOI: 10.1371/journal.pone.0276482
Provided by the Public Library of Science
Reference: Octopuses caught on video throwing mud and shells around themselves and at each other (2022, November 9) Retrieved November 9, 2022 from https://phys.org/news/2022-11-octopuses-caught -video-silt-shells. html
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