New York

Octopuses may have more complex social interactions than previously believed, a new study has found. Biologists studied a group of Sydney octopuses off Australia’s east coast and observed a range of behaviour that may indicate complex social signalling.

Octopuses that stand tall, turn dark and spread their web in a ‘Nosferatu pose’ are likely showing aggression. Conversely, octopuses may display a pale colour after losing a fight or when trying to avoid conflict. It was previously believed that octopuses were largely solitary creatures. Changes to body colour and other behaviour were interpreted as tactics to avoid predators. But Prof Peter Godfrey-Smith from the City University of New York, US, said the study provided a novel perspective on octopus behaviour. ‘[An aggressive] octopus will turn very dark, stand in a way that accentuates its size and it will often seek to stand on a higher spot,’ Prof Godfrey-Smith, who co-authored the report, told the BBC. ‘Clearly the unusual stance is not a physiological response. It makes it look as big as it can possibly be, with its arms spread out below and the mantle, the back part of the animal, raised over the head.

‘The dark colour is produced in concert with those size-accentuating behaviours. There’s no particular physiological reason why darkness should be associated with aggression, but it does give the impression of a larger object.’ The researchers, based in Australia and the US, dubbed the stance the ‘Nosferatu pose’, referring to the classic 1920s horror film, because the spread of the octopus’s web was reminiscent of a vampire’s cape.