Not all octopus mating ends with male’s death

Published August 31, 2015 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2015 Susan Scott

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A day octopus on Oahu’s North Shore. ©2015 Susan Scott

When courting, what does the male larger Pacific striped octopus sing to the female larger Pacific striped octopus?

“I want you back in my arms, arms, arms, arms, arms, arms, arms, arms again.”

For most octopus species, this would never be the song of choice because female octopuses sometimes eat their baby daddies. If males want to live to fertilize again, they must keep the object of their affection at arm’s length.

The larger Pacific striped octopus (LPSO for short), however, has a more friendly style of mating. In a recent study published in the online journal PLOS One, California researchers report that pairs of this species from the Pacific coast of Central America mate beak to beak, their 16 arms wriggling, grappling and hugging.

Typical octopus sex is as odd as the creatures themselves. Males have one specialized arm that stores and delivers sperm.

In most species, when a male and female meet, the male keeps his distance, stretching the loaded arm out to the female to deposit his sperm packet internally.

octo
Courtesy Arcadio Rodariche.

In one Tahiti study of the day octopus, Hawaii’s most common species, a male reached out and fertilized the same female 12 times in about three hours. He should have rolled over and gone to sleep: On the 13th transfer she ate him.

The word “larger” in the name “larger Pacific striped octopus” refers to a close cousin, the lesser Pacific striped octopus having a mantle about the size of a strawberry. The larger species’ mantle is about size of a tangerine.

An octopus mantle is the bag of flesh that in cartoon octopuses is depicted as a bulbous snout or bulging brain. It’s neither. The sack houses the octopus’s three hearts, liver, kidney and other internal organs. The animal’s impressive brain lies below the mantle between the eyes.

The 24 LPSOs in the California study had no interest in sexual cannibalism. One couple even shared a den and sometimes a meal, an oddity among octopuses, which usually lead solitary lives.

The LPSO researchers found another unique behavior in a hunting trick similar to the grade school prank of reaching behind someone and tapping them on the far shoulder to get them to turn the wrong way.

The LPSO does that, too, slowly reaching an arched arm, suckers up, over the top of a shrimp and giving it a tap it on the front of its upper shell. The startled shrimp scoots backward into the waiting predator.

Worth checking out are six short LPSO behavior videos near the end of the study. In the mating one, I imagine the grasping male singing, “I want to hold your hand, hand, hand, hand, hand, hand, hand, hand.”


Marine biologist Susan Scott writes the newspaper column, “Ocean
Watch”, for the Honolulu Star-Advertiser, www.staradvertiser.com

©2015 Susan Scott