If recent octopus discoveries have taught us anything, it's that these eight-armed ocean dwellers are smart. They can use tools, change color in an instant, and commission their arms to solve problems. But they generally do all this as loners.

Now, new research into a surprisingly social octopus is shattering even the most expansive ideas of known octopus behavior. (Related: "Journey of Octopus Discovery Reveals Them to Be Playful, Curious, Smart.")

Panamanian biologist Aradio Rodaniche first reported the Pacific striped octopus in 1991 off the coast of Nicaragua, noting its strange behavior—living in groups of possibly up to 40, laying multiple egg clutches, and mating face-to-face and sucker-to-sucker. Most other octopus species, for instance, come together only to mate.

But scientists didn't see