A rarely studied breed of tropical octopus is gentle with its prey and rough with its sex, according to research published Wednesday by UC Berkeley and California Academy of Sciences researchers.
The researchers observed the larger Pacific striped octopus in captivity between 2012 and 2014 and recorded its social, sexual and feeding patterns, according to the journal PLOS ONE.
The species was first studied in the 1970s in Panama by Arcadio Rodaniche, a co-author in the study. The limited scope of his observations prevented him from publishing a conclusive study at the time, according to co-author Roy Caldwell, a UC Berkeley professor emeritus of integrative biology.
Co-author Christine Huffard, a research associate at the California Academy of Sciences, said this species challenges prevailing assumptions that octopuses are mostly solitary creatures. Rodaniche previously observed groups of up to 40 octopuses off the coasts of Central America, according to the study.
The larger Pacific striped octopus will also occasionally share a den with a member of the opposite sex for up to several months, a phenomenon that co-author Richard Ross, a senior biologist at the California Academy of Sciences, said is unheard of among other octopus species in the wild.
Ross described the creature’s hunting style as “reminiscent of a tiger.” When the octopus feeds, it will extend a tentacle and lightly tap its food — a shrimp, for instance — to scare the prey directly into its arms.
“Most octopus don’t do that — they’ll just see something and leap at it to catch it,” he said. “This right here is an example of the hunt at its finest.”
Ross highlighted their mating patterns, which he calls “crazy nutty,” because unlike other species, these octopuses mate beak-to-beak and can lay multiple clutches of eggs for extended periods of time.
Male octopuses typically transfer their sperm to females from a distance or by mounting, according to the study. This species, however, will engage in grappling — in which the male will fully envelop itself into the female’s mouth cavity — which is normally associated with signs of aggression.
Janet Voight, an associate curator of zoology at the Field Museum in Chicago, views this behavior as a way for the female to assess her potential mating partner before sex.
“The females are being choosy,” she said. “If you’re not a confident-enough octopus to push me ‘X’ millimeters, you’re not going to copulate with me.”
Caldwell said that while there are more than 300 known species of octopuses, most of what has already been researched comes from a select few species.
“This study brings to light that there may be other species that are doing just the same things or even more bizarre behaviors,” he said.
Caldwell addressed the difficulties faced by those who wish to study the animals in the wild, because they inhabit deep waters with low visibility, strong currents and muddy planes. While his team hopes to plan an expedition in the near future, they have been unable to thus far.
Still, Huffard said studying a species as unique as this one showcases the “incredible diversity” of animal life and behavior in understudied habitats.