Scientists have found more evidence that shows octopuses, especially those off the east coast of Australia, aren’t the lonely creatures we think they are.
They like living close together, in the form of a village, and regularly communicate via posturing, fighting, chasing or colour changes.
Researchers found the home of up to 15 gloomy octopuses (Octopus tetricus) in Jervis Bay, NSW.
According to findings reported in the journal Marine and Freshwater Behaviour and Physiology, the new site is the second gloomy octopus settlement found in the area.
In 2016, the researchers reported finding a village of sorts used by more than 50 octopuses on the sea floor about 17 metres deep in Jervis Bay.
“At both sites there were features that we think may have made the congregation possible — namely several seafloor rock outcroppings dotting an otherwise flat and featureless area,” says Stephanie Chancellor, a PhD student in biological sciences at the University of Illinois at Chicago and an author on the paper.
“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.”
This new octopus site, about 100 metres away from the first site, has been dubbed Octlantis by the researchers. It is 10 to 15 metres underwater, about 18 metres in length and four metres wide.
It is made up of a few patches of exposed rock and beds of discarded shells. A total of 13 occupied and 10 unoccupied octopus dens — holes excavated into sand or shell piles — were found.
Here’s footage from the first octopus village at Jervis Bay:
The researchers placed four GoPro cameras at the new site to film for a day, recording 10 hours of footage that showed numerous social interactions among the inhabitants. The number of octopuses observed at the site ranged from 10 to a high of 15.
“Animals were often pretty close to each other, often within arm’s reach,” says Chancellor.
“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 another animal observing this behavior would quickly swim away.”
Here’s a sketch of the octopus site in Jervis Bay:
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