Two octopuses have been recorded throwing shells at each other on an underwater camera set up beneath the ocean near Australia.
It’s the first time that the unusual behavior has been observed in the species and researchers recorded over 100 instances of the octopuses chucking silt and shells at one another.
The video, filmed in Jervis Bay, Australia, was shot in 2014 and 2015 and a team analyzed nearly 24 hours’ worth of footage and published their findings in Plos One recently.
The collection of videos shows the eight-armed cephalopods gathering debris from the ocean floor and then shooting it with their siphon and arms toward its nemesis.
Even though octopuses have previously been observed shooting sand from their siphon, it’s the first time the technique has been used to launch a seashell.
How it Was Filmed
To capture the behavioral data the research team used stationary video cameras on tripods at 17 meters deep. They used mainly GoPros.
“Having informally observed what appeared to be ‘shell throws’ on several occasions, we examined our video records for behaviors of this kind,” the researchers say.
The octopuses in question are gloomy octopuses and are native to the waters off the coasts of Australia and New Zealand. The eight-legged creatures mainly eat mollusks but have also been observed eating members of their own species.
According to Gizmodo, the researchers observed that only 17 percent of the throws hit their intended target, with half of all throws aimed at other octopuses.
The octopuses occasionally targeted the researcher’s cameras. 12 times material was thrown toward a stationary camera and two successful hits came when the camera was accidentally placed closer to the octopus dens than usual.
“The usual camera distance is about a meter or slightly more from the nearest den, and this placement was closer by approximately a third of that distance. During this period, the octopus in the den closest to the camera threw material six times in the direction of the camera, out of 18 throws during that period, including the two hits.”
The Behavior is Unexplained
Both male and female octopuses were observed throwing seashells at each other and researchers don’t know exactly why.
However, what’s fascinating is that these octopuses are using projectiles in a way that’s previously only ever been observed in social mammals. This leads the researchers to believe that at least some of the throws are intended as communicative, agonistic, or a social tool.
It’s worth noting that octopuses are generally anti-social but sometimes show tolerance of other individuals. They are considered to be intelligent creatures.