Octopuses Might Not Be Loners, Study Shows
While little is known about the typically solitary lives of octopuses, new evidence out of Australia suggests that octopuses can congregate and socialize under the right conditions.
According to findings reported this month in the journal Marine and Freshwater Behaviour and Physiology, researchers studying a newly discovered group of about 15 octopuses off Australia’s east coast observed the animals communicating through such behaviors as posturing and chasing.
Octopuses are not thought to be the most social of creatures. Mating, for example, is typically the only interaction between males and females, who go their separate ways once it’s over.
The Australian site is one of several octopus settlements – areas where multiple octopuses congregate and communicate with one another – that have been found in recent years in Jervis Bay.
“At both sites [studied], there were features that we think may have made the congregation possible — namely several seafloor rock outcroppings dotting an otherwise flat and featureless area,” said Stephanie Chancellor, a Ph.D. student in biological sciences at the University of Illinois at Chicago and co-author of the study, in a press release. “In addition to the rock outcroppings, octopuses who had been inhabiting the area had built up piles of shells left over from creatures they ate, most notably clams and scallops. These shell piles, or middens, were further sculpted to create dens, making these octopuses true environmental engineers.”
The newly discovered settlement, dubbed Octlantis, is 10 to 15 meters beneath the water’s surface and features 13 occupied and 10 unoccupied octopus dens – holes excavated into sand or shell piles.
Chancellor and other researchers placed four GoPro cameras at the new site to film the octopuses for a day, recording 10 hours of footage that showed numerous social interactions, including mating, signs of aggression, chasing and other signaling behaviors.
“Animals were often pretty close to each other, often within arm’s reach,” Chancellor said. “Some of the octopuses were seen evicting other animals from their dens. There were some apparent threat displays where an animal would stretch itself out lengthwise in an upright posture and its mantle would darken. Often other animals observing this behavior would quickly swim away.”
Octopuses expend large amounts of energy during antagonistic behavior, which Chancellor said can lead to a potential risk of injury. The behavior could be territorial, but more research is needed to understand octopus behavior in general, she said.
“We still don’t know what the benefits are of this kind of behavior, which is linked closely to living in densely populated settlements, compared to the life of a solitary octopus,” Chancellor said.
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