Octopuses are widely considered solitary animals, typically leaving their dens only to hunt crabs, lobsters, and other prey. But researchers studying waters in Jervis Bay first challenged that assumption in 2021, when they documented a cluster of gloomy octopuses (Octopus tetricus) living unusually close together, mating and fighting — even during the day.
Now, scientists have identified a second site a few hundred meters away. The newly observed structure contains 23 dens and supports up to 15 octopuses, which were seen competing for shelter, chasing rivals, and displaying threat postures by raising their bodies and darkening their skin.
The findings add to the growing evidence that octopuses may be more socially flexible than once believed. Though interactions can be dangerous, researchers say that animals may benefit from living together because their behavior gradually reshapes the habitat. As octopuses return from hunts they discard shells near their dens. Over time, these shell piles stabilize the seafloor, allowing additional dens to form and creating a suitable living environment.
The area offers plentiful food but limited shelter and many predators, meaning clustered living may provide better protection for the creatures than isolation.
Scientists also observed differences between the studied groups of octopuses. Some octopuses are more active than others, frequently leaving dens, approaching neighbors, or attempting to dive rivals away.
While such social arrangements have been observed in the wild, they are difficult to replicate in captivity, where octopuses may attack or eat one another. Cannibalism remains a known risk. Research conducted in Spain has suggested that octopuses can be an efficient food source for one another, providing high protein with relatively low effort compared to hard-shelled prey.
The discoveries highlight how much remains unknown about octopuses’ behavior, and suggest that even famously solitary species may be more socially complex than once thought.
