Octopuses use body colour and posture to communicate to others during aggressive encounters, suggesting that they are more social than previously thought.

Octopuses are considered to be more solitary animals than many squid or cuttlefish. David Scheel of Alaska Pacific University in Anchorage and his colleagues reviewed filmed interactions between pairs of Octopus tetricus off the coast of New South Wales, Australia. Octopuses were darker when they were about to fight an approaching animal and paler when they were set to flee. When dark in colour, the animals also changed their posture — by standing tall on higher ground and spreading the webs between their arms.

The octopuses could be using these signals to communicate their size, strength and willingness to fight to a rival, the authors say.

Curr. Biol. http://doi.org/bb6f (2016)