The octopus, by in large, practices very safe sex. You would, too, if you and the object of your affection were both cannibals.

But the algae octopus (Abdopus aculeatus) has developed a relatively sophisticated mating system that involves far more close contact than many other octopus species.

In populations of these cephalopods, males and females often live close together. Given this arrangement, the males can sometimes mate with females without even entering the female's den—simply by reaching their long mating arm inside the den and to the female. However, sometimes, the biggest local male will instead guard a particularly large female's den, keeping the mating privileges for himself.

In the instance captured on video--by Monterey Bay Aquarium Research Institute scientist Crissy Huffard--a shopping male finds an eligible female's den. He is seen reaching out his mating arm and stretching it into the den's opening. Once an octopus emerges, the male continues with his advances, appearing to fish around with his arm looking for her funnel opening. But from there things don't go quite as the advancing male might have imagined.

The newly emerged octopus was not a female but, rather, a guarding male. This larger male very quickly rejects the smaller male's overtures and lashes out. A wrestling match of writing arms ensues before the smaller male is able to escape and jet away, leaving the larger male to saunter back to his female.

The guarding male does not always come away looking so cool, however. Even with these larger males guarding a female, smaller males still stand a chance. These males can become "sneakers"—slinking into a female's den while the guarding male is away, Huffard has observed. To play it safe, however, sometimes they disguise themselves as females, hiding their male features. In one of these cases, the guarding male returned to the den to find—what he thought to be—another female. He might have been delighted (as delighted as an octopus could be) to find, what luck, another potential female mate! But when this guarding male tried to put the moves on the sneaker, the sneaker's true sex was revealed. And let's just say neither was pleased.

These accidental advances are also interesting given recent research about how octopus scents might play a role in finding a suitable mate. Most likely the guarding male was not emitting fake female pheromones. But perhaps the unsuspecting suitor was getting whiffs of the nearby female but not aware that the scent was emanating from elsewhere than the octopus that emerged.

No one said mating isn't an occasionally awkward endeavor.

Learn more about the strange world of the octopus and its mating rituals in Octopus! The Most Mysterious Creature In the Sea, which publishes in paperback on November 25!

Illustration courtesy of Ivan Phillipsen