Tag Archives: cephalopod

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.

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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

 

Here is one cephalopod that will be tough to forget

Published February 16, 2015 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2015 Susan Scott

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Port Angeles, Wash. » While spending a few days in this town on the Olympic Peninsula, my friends took me to the Feiro Marine Center, where I fell in love with a giant Pacific octopus named Obeka.

“Giant” is part of the animal’s common name because this North Pacific species is the largest in the world. Adults grow to 110 pounds and, when spread out like an umbrella, can measure 20 feet across from arm tip to arm tip.

This female octopus isn’t fully grown.

She weighed 1 pound when brought to the center a year ago. Now she weighs 35 pounds with a span of nearly 7 feet.

Obeka is a striking life form. When I first saw the vivid-orange octopus, she was resting, her head hidden behind huge suckers stuck on the aquarium glass.

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A giant octopus has about 1,600 suckers. The largest on an adult are 2 1⁄2 inches across and can support about 35 pounds each.

The outer edge of the sucker contains ridges that help prevent slipping when clamped down. Muscles control the shape of the inner wall, creating the suction force for each individual sucker. But these suckers do more than suck. They taste what they touch.

With hundreds of round “tongues,” the octopus can hunt in total darkness and find food under rocks and in cracks.

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Food in this case is anything the creature can catch, including birds. A giant octopus once astonished Washington state ferry workers by hiding under a rock near the terminal.

When a gull landed on the exposed surface at low tide, a suckered arm appeared from below, grabbed the unsuspecting bird and hauled it below for a meal.

The stories about giant octopuses slithering out of covered aquarium tanks to go hunting in a neighboring tank are true. Even though the boneless animals look like slimy blobs out of the water, their muscular arms and suckers still function on dry surfaces and can pull the body along for short distances.

Obeka so impressed me that I bought a book about giant octopuses. After reading a bit and chatting with the center’s workers, I revisited Obeka’s tank to tell her how extraordinary and beautiful I thought she was.

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As if hearing me, she woke up, looked at me with intelligent eyes and crawled around her tank seemingly posing for pictures.

Before Obeka grows to full size, the marine center will return the potential mother to her ocean home to reproduce. She’ll die soon after her 68,000 eggs hatch (giant octopuses live about four years), but she will have left more than baby octopuses. In saying hello to a writer who can share the glory of the giant Pacific octopus, she has helped people appreciate these remarkable animals. Your species thanks you, Obeka. As does ours.


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

©2015 Susan Scott