Octopuses were caught on camera throwing shells at each other
Underwater cameras have captured more than 100 incidents of dusky octopuses throwing mud and shells at each other in Australia’s Jervis Bay.
The nearly 24-hour video was shot in 2014 and 2015, but only now has the footage been fully analyzed. The team of researchers who studied the behavior have published their findings today in Plos One.
Dark (or common Sydney) octopus (A tentacled octopus) is native to nearshore waters Australia and New Zealand. It has a rusty brown complexion and white eyes. The octopus primarily eats molluscs, but has also been documented to eat members of its own species. according to the Australian Museum.
In the videos, the eight-armed cephalopods scoop up material from the sea floor, like silt and shells. and then push it through the water using their siphon and hands. Octopuses have been around before quicksand was observed from their siphon, but never eject larger objects such as shrimp.
The researchers found that the octopuses had to move their siphons into an unusual position, under the web of the octopus’s arms, to retrieve the material, indicating that they were deliberately throwing the material.
The teams observed both sexes throwing material; about half of the throws were done while interacting with other octopuses. Only about 17% of the throws actually hit their targets, so if you’re a sports agent reading this, think twice before signing up a gloomy octopus. The eight arms clearly aren’t as much of an advantage as they seem.
And if we’re splitting hairs (or gills, or whatever), the octopuses are not hurling objects at their foes, Cy Young-style. The propulsion is entirely driven by their siphons; the arms are simply directing the material.
But look up definition “to throw“. Technically, that’s what octopuses do, though it’s a loose enough connection that researchers call the action “throws,” in quotes.
Because some of the throws were by male octopi and some by female octopi, and they occurred both in the presence and absence of other octopi, the researchers aren’t exactly sure of the motives here. At least in some cases, the team believes the throws serve a social purpose. And considering that in some of the videos the octopuses are literally covered in slime thrown at them by a nearby octopus, that seems about right.
Octopuses are generally antisocial, the researchers noted in the study, but sometimes show tolerance toward other individuals. But what it means to cover another member of your species in silt, algae, and shells may require further study.
Throwing behavior puts the dusky octopus on the short list of species that have demonstrated throwing behavior, along with chimpanzees, capuchin monkeys, elephants, polar bears, Egyptian vultures and several others.
Octopuses are very bright creatures. They probably have good reason to stake things. We just have to be bright enough to figure out what they’re up to.
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