"This is not a unique species of octopus, which suggests others behave this way," said Roy Caldwell, a professor of integrative biology at UC Berkeley and co-author of the study.
In the wild, researchers observed macho octopuses that didn't just mate with the first female that crossed their path. Many picked out a specific sex partner and jealously guarded her den for several days, warding off rivals to the point of strangling them if they got too close. When flirting or fighting, they would signal their manliness by displaying striped body patterns.
Researchers also saw small "sneaker" males that moved in on unsuspecting conquests by masquerading as females. They did this by swimming low to the ground in feminine fashion and not displaying their "male" brown stripe. Plus, for the males, size really mattered: "If you're going to spend time guarding a female, you want to go for the biggest female you can find because she's going to produce more eggs," Caldwell said. "It's basically an investment strategy."