Underwater video cameras have recorded more than 100 instances of shadowy octopuses spewing slime and shells at each other in Jervis Bay, Australia.
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The video footage, approximately 24 hours long, was captured in 2014 and 2015, but only now have the videos been fully analyzed. The team of researchers who studied the behavior has published their findings today at Plos One.
The brooding (or common Sydney) octopus (octopus tentricus) is native to the waters off the coast of Australia and New Zealand. It has a rusty brown coloration and white eyes. The octopus eats mainly molluscs, but it has also been documented that it eats members of its own species, according to the Australian Museum.
In the videos, the eight-armed cephalopods scoop up material from the seafloor such as silt and shells. and then push it through the water using its siphon and arms. Octopuses have previously been observed shooting sand from its siphon but never launching more substantial objects like seashells.
The researchers found that the octopuses had to move their siphons to an unusual position, under the web of the octopus’s arms, to expel the material, indicating that they were intentionally spewing it out.
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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 the definition of “throw.” Technically, that’s what the octopuses are doing, though it’s a tenuous enough connection that researchers refer to the action as “throws,” in quotes.
Because some of the releases were from male octopuses and some from female octopuses, and occurred both in the presence and absence of other octopuses, the researchers aren’t exactly sure why here. In at least some cases, the team believes the releases 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 with slime, algae, and shells may require a closer look.
The launching behavior places the sooty octopus on a short list of species that have exhibited a type of launching behavior, along with chimpanzees, capuchin monkeys, elephants, polar bears, Egyptian vultures, and some others.
Octopuses are very bright creatures.. They probably have a good reason for throwing things.. We just need to be smart enough to figure out what they’re up to.
More: Researchers Finally Figured Out How Octopuses Taste With Their Arms