Watch Octopuses Hurl Shells at Each Other in Bizarre Underwater Brawl


Agroup of wild octopuses have been caught on camera hurling silt and shells at each other in first-of-its-kind footage.

Researchers in Jervis Bay, Australia, used underwater cameras to monitor the behavior of the population over several days and have reported their results in a paper published by online journal PLOS One.

"The throwing, propelling or projecting of objects is rare in the animal kingdom," Peter Godfrey-Smith, a professor at the University of Sydney who led the study, told Newsweek. "To propel an object, even for a short distance, underwater is especially rare and also quite hard to do."

In the footage, the octopuses can be seen gathering objects like silt, shells and algae in their arms and then "throwing" them using jet propulsion. "Most throws do not hit any other octopus and are pretty clearly not intended to," Godfrey-Smith said. "But some do appear to be targeted."

Octopus tetricus, aka the gloomy octopus, is commonly found in the subtropical waters of eastern Australia and New Zealand. Godfrey-Smith said that their nickname was inspired by the "world-weary look" in their eyes.

Octopuses in general are known for being pretty antisocial. They hunt alone, fight after an encounter and sometimes even eat each other. However, food sources are locally abundant in Jervis Bay, and suitable shelter in the surrounding area is scarce. As a result, octopus populations in this area are forced to live close together.

In these cramped conditions, they need to work hard to mark their territory. Previously, they have been observed standing tall above their competitors and darkening their body color to appear more intimidating.

In the new study, octopuses with darker shades threw more forcefully and were more likely to hit others, suggesting there were targeted signs of aggression rather than accidental ones.

"It is very hard to know about the intentions of an animal like this," Godfrey-Smith said. "I suspect the behavior can be something like an assertion of personal space."

Octopuses have been previously shown to use this jet propulsion to clean debris and discarded food out of their dens. However, the footage shows that their arms took on a particularly unusual position when they were seen throwing objects at other octopuses, suggesting that the actions were intentional.

Targeted throwing is an uncommon behavior in animals and is thought to have a significant role in human evolution. "It probably became an important behavior in the hunting of larger animals, [such as throwing spears," Godfrey-Smith said.

Throwing at a target has also been seen in a small number of social animals, such as chimps, elephants, mongooses and birds. This footage provides the first evidence that the antisocial octopus may also engage in these targeted social behaviors.

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