Octopuses are social animals that change colors to resolve disputes and even throw debris at each other, video footage of a group of the feisty sea creatures in Jervis Bay has shown.
The octopuses’ unusual behaviour was first observed by a local diver — study co-author Matthew Lawrence — who mentioned their social gathering on a cephalopod enthusiast website.
It immediately attracted the attention of an international team of octopus experts, including Professor Peter Godfrey-Smith from the University of Sydney and City University of New York and Professor David Scheel from Alaska Pacific University.
They set up underwater cameras to film the octopuses interacting.
The study, published today in Current Biology, documents a very rare example of octopuses living in a group.
Octopuses have generally been viewed as solitary creatures, and their color-changing abilities primarily as a means to hide from hungry predators.
But after binge-watching hours of footage, the researchers discovered not only did the octopuses live together, they also used their color-changing abilities, along with extreme body postures, to avoid conflict in social interactions with other octopuses.
Up to a dozen Sydney octopuses (Octopus tetricus) inhabit a three-metre-square area in the middle of Jervis Bay, with the site centring on an encrusted object in the midst of a sandy expanse.
(A darker colored octopus attacks another octopus, which turns a light color. Credit: Peter Godfrey-Smith, David Scheel, Matt Lawrence, Stefan Linquist)
“Octopus began living there and dropped the shells of the scallops they had eaten. Over time the shell midden built up, providing good building materials for new arrivals to create dens,” Professor Godfrey-Smith said.
But the octopuses were not hanging about because they liked each other or wanted to be in close proximity, he said.