A group of octopuses was captured in video footage throwing silt and shells at each other in Jervis Bay, Australia, in what a study's researchers believe is part of a bizarre social behavior.

Underwater video cameras were able to capture more than 100 instances of gloomy octopuses hurling objects at other octopuses. The footage, which is worth 24 hours, was taken in 2014 and 2015 but was only recently fully analyzed. The researchers that studied the footage published their findings in Plos One.

Octopuses Throw Silt, Shells at Each Other

The gloomy (or common Sydney) octopus (Octopus tentricus) is commonly found in the waters off the coasts of Australia and New Zealand. This type of octopus is identifiable by its rusty brown coloration and white eyes. The creatures in the area mostly eat mollusks but have also been seen eating members of their own species.

In the footage, the eight-armed creatures gather up material from the seafloor, including silt and shells, and use water to push the materials. The animals have previously been documented shooting sand from their siphon but have never been observed throwing more substantial objects such as seashells, as per Gizmodo.

The team of researchers discovered that the octopuses had to move their siphons into an unusual position in order to push the materials out. They had to place them under the web of their arms. This behavior is seen as evidence that they were intentionally throwing the materials.

The team also observed both sexes, males and females, throwing material, with about half of the throws being done amid interaction with other octopuses. Only about 17% of the throws were actually able to hit their targets.

According to the New York Times, despite the intelligence that octopuses possess, they primarily live solitary lives. But the unusually large members of the species that were documented were found gathering at sites that have been nicknamed Octopolis and Octlantis.

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Bizarre Social Behavior

There are several factors that force the normally anti-social octopuses in the area into close proximity with each other, including ideal denning conditions and abundant food. In the crowded waters, it is normal for the animals to poke, prod, grab, and otherwise annoy each other.

A philosopher of science at the University of Sydney in Australia, Peter Godfrey-Smith, who is an author of the study, said that the throwing was not at all routine. He said that it was still being observed reasonably often among the animals.

Janet Mann, a biologist at Georgetown University, said that octopuses are very intelligent, being able to propel water to swim. Some who are in captivity have also been known to squirt water at humans. Mann, who was not part of the study, said that she was not surprised that the animals use water as a tool.

In one instance, the researchers also observed a female octopus repeatedly throw silt at a male octopus who was trying to mate with her, with the target avoiding the hits by ducking out of the way of the projectiles. Godfrey-Smith said that in some cases, the target would hold its tentacles up between itself and the thrower, in what is believed to be an anticipation of the projectile, the University of Sydney reported.

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