The social life of octopuses.

Quark goes deep to plumb the mysteries of the cephalopod city scientists have dubbed “Octlantis”:

In Jervis Bay, off Eastern Australia, researchers recently spotted 15 gloomy octopuses congregating, communicating, dwelling together, and even evicting each other from dens at a site the scientists named “Octlantis.” The international team of marine biologists, led by professor David Scheel of Alaska Pacific University, filmed these creatures exhibiting complex social behaviors that contradict the received wisdom that these cephalopods are loners. Their study was published in the journal Marine and Freshwater Behavior and Physiology.

At least one other gloomy octopus site was found recently, though; it was discovered in 2009, not far away in Jervis Bay, and named Octopolis. At that time it was considered a total anomaly. Researchers believed that the cephalopods gathered there because an unidentifiable human object happened to have formed a central point that the cephalopods surrounded with dens. The unknown artifact was a single object about 30 cm long, heavily encrusted, possibly made of metal. The site has been observed for seven years now, and at any given time, there are somewhere between two and 16 octopuses there.

In Octlantis, however, there is no similarly mystifying human object to explain the gloomy octopus congregation.

Citizens must be scrappy. The company and food are abundant but all the activity in the cities also attracts predators, including sharks.
There’s also a lot of aggression apparently, although the researchers can’t yet explain why. Gloomy octopus males seem to spend a great deal of time chasing each other out of dens.

Gloomy octopuses aren’t the only supposedly solitary cephalopods to have been spotted interacting socially in the last decade.

Scheel believes that octopus behavior probably hasn’t changed in that time. Rather, humans’ ability to observe the behavior has. Today more divers are in the water with cameras and better technology to quickly communicate findings amongst divers and scientists.

(And yes, that really is the plural.)