The octopus already is an oddball of the ocean. Now biologists have rediscovered a species of that eight-armed sea creature that's even stranger and shares some of our social and mating habits. Biologist Rich Ross and colleagues studying a batch of octopuses from Central America found the critters just didn't fit the loner denizen-of-the-deep profile that scientists had drawn for the rest of the 300 or so octopus species. While most octopuses live alone, coming together for ever-so-brief and dangerous mating, couples of this species can live together to mate for a few days in the same cramped den or shell. While other male octopuses mate from a distance to avoid being cannibalized, these octopuses mate entangled beak-to-beak in an almost romantic style, an expert says.
While other females lay one batch of eggs and then die, the female of this species lives longer and produces eggs constantly, bettering the species' chance of survival, Ross says. But it's more than sex. These octopuses clean out food waste from their dens, twirl their arms, sport sudden stripes and spots when excited or upset, and quickly learn that people mean food: When someone enters the room, they leave their dens and head to the top of the tank. "It's the most amazing octopus that I've ever gotten to work with," Ross says. The species is preliminarily called the Larger Pacific Striped Octopus, although it's really not much bigger than a tennis ball—just bigger than a similar species. It was found almost 40 years ago off the coast of Panama by Arcadio Rodaniche, but other scientists didn't believe it was a separate species, so it was never formally described or named until now. (Read more octopus stories.)