Researchers Are Surprised to Learn that Octopus Are Social
In 2009, researchers discovered octopuses living in close proximity at a site in Jervis Bay, Australia – dubbed ‘Octlantis’. Mating and fighting were observed among a group that numbered between two and 11. It was thought that a scrap of metal or man-made object may have provided the first bit of shelter around which the animals could congregate.
A few years later, scientists were surprised to discover another site of wild octopuses living at a high density. Even more interesting: the site was completely natural.
This second site, on a patch of rocky outcrop, accommodated between 10 and 15 animals of varying sizes. As well as mating and fighting, the scientists saw frequent, complex social interactions including eviction of octopuses from dens and exclusion of individuals.
So why do these octopuses choose to live together? It turns out that a chain of activity creates an ideal living environment. The octopuses go out to find food, which they bring back to eat in the safety of a den. Then, they toss the shells out, which build up over time. The shell bed stabilizes the soft sediment and allows the animals to build more dens and create more habitats. Corresponding author Professor David Scheel of the Alaska Pacific University thinks the habitat area wouldn’t be stable without the shells.
“We suspect that this is an area where there’s a lot of food, relatively scarce shelter and plenty of predators,” said Scheel. “If you put that story together it seems that shelter is the most important thing.”
These are the first occasions scientists have had to watch this species interacting repeatedly over time. Filming and observing octopus’ behavior in the wild is challenging.
While most octopuses are likely to be solitary for most of the time, scientists may have underestimated the importance of the moments of interaction. “They do happen for most or at least sometime in their lives. And for some octopuses, very commonly. Octopuses can use behavior that they don’t need when they’re solitary.”
The research joins findings about other unusual social behaviors such complex visual signal use in octopus and beak-to-beak mating, as well as co-occupancy of dens in the Larger Pacific Striped Octopus while in a mating pair.