Image: GodfreySmith et al./PLOS One/Reproduction
American and Australian scientists have observed squid hurling sand and debris at each other in Jervis Bay off the coast of New South Wales, Australia. The full study was published in the journal PLOS One.
The team examined 24 hours of footage taken on the seabed between 2015 and 2016. In all, the researchers identified 102 episodes of octopuses catching and flinging clams, algae, or slime. A total of about ten animals were analyzed, all of the Octopus tetricus type.
Octopuses didn’t use their tentacles for their shenanigans. In fact, it was even more complicated: the arms were only used to collect the items, which were then flung from jets of water ejected from a siphon beneath the tentacles. The siphon is an internal funnelshaped muscle that animals also use to thrust and flee at high speeds.
Both male and female octopuses have been observed throwing things at each other. However, women did so more often, accounting for 66% of recorded pitches.
Octopuses threw debris to clean their burrows 32% of the time. In this case, it was more common for the animals to pick up mussels or algae. On the other hand, octopuses were seen throwing slime at other animals 53% of the time.
The targets were hit 17 times. It was common for the animal in the crosshairs to lower itself or raise its tentacles to protect itself from the projectile upon the arrival of the slime. According to the researchers, a difference can be seen between the targeted launches of the octopuses and the harmless ones.
Few animals throw things at each other. The behavior has already been observed in chimpanzees and dolphins, for example, but unlike squid, these are social animals.
Octopuses live alone and when they encounter other members of their own species, they can fight them and even engage in cannibalism. But the new evidence suggests some species may be communicating via the launches, perhaps warning that this is their territory and that they have no intention of sharing the space.
In Jervis Bay, for example, food and shelter are plentiful, which attracts many squid. Since the animals must occupy the same region, they at least know the boundaries that they may or may not cross with their neighbors, even if they learn to do so with rocks.