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Deep-Sea Octopus is Mother of the Year

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This deep-sea octopus spent four and one half years brooding her eggs on a ledge near the bottom of Monterey Canyon, about 4,600 feet below the ocean's surface. (Courtesy MBARI © 2007)

This deep-sea octopus spent four-and-a-half years brooding her eggs on a ledge near the bottom of Monterey Canyon, about 4,600 feet below the ocean’s surface. (MBARI © 2007)

Think 9 months of morning sickness and swollen ankles sounds rough?

Imagine being pregnant for 4 years.

In a new study published today, researchers from the Monterey Bay Aquarium Research Institute report a deep-sea octopus that tends its eggs for a mind-numbing 53 months.

During her 53-month brooding period, the mother continually kept her eggs free from silt and protected them from predators. (Courtesy MBARI © 2009)

During her 53-month brooding period, the mother continually kept her eggs free from silt and protected them from predators.
(MBARI © 2009)

The researchers discovered the female octopus during a routine deep-sea survey of Monterey Canyon in 2007. Using a remotely operated vehicle, they watched her brood a clutch of approximately 160 eggs nearly a mile below the ocean’s surface.

Although brooding females of this species (Graneledone boreopacifica) had been observed in the past, this was the first time the researchers witnessed the entire event from start to finish.

“It was very exciting to find that octopus at the very beginning of the egg-brooding period,” says Brad Seibel, a professor at the University of Rhode Island and a study co-author. “You can find them fairly easily already attached to the rocks and somewhere in the middle of the egg-brooding period, but to find one right at the beginning was a stroke of luck.”

Over the next four-and-a-half years, the researchers visited the nursery 18 times. They watched as her translucent eggs grew larger, miniature cephalopods taking shape inside.

The empty egg cases found in 2011. Because the young octopus in these eggs had so long to develop, they were able to swim and hunt soon after hatching, which increased their odds of survival. (Courtesy MBARI © 2011)

The empty egg cases found in 2011. Because the youngsters had so long to develop, they were able to swim and hunt soon after hatching, increasing their odds of survival.
(MBARI © 2011)

But they never saw the mother leave her clutch.

“As far as we know, she sat there and didn’t move,” said Seibel.

And they never saw her eat.

The mother’s health slowly declined — she lost weight, her skin became slack and pale (by octopus standards), and her eyes grew cloudy. Finally, on a visit late in 2011, the octopus was gone. Only tattered egg casings remained.

It’s typical for female octopuses to sacrifice themselves for their offspring, hardly eating as they tend and protect their eggs. But being able to survive for more than four years without food is an impressive feat even among cephalopods. The previous egg-brooding record, set by Bathypolypus arcticus, was a mere 14 months.

The extreme 53-month brooding period gives the baby octopuses a competitive advantage. They hatch as tiny adults and are more capable of hunting and surviving in the deep ocean.

But how the mother survives for so long remains something of a mystery.

Seibel says that the study shows just how little we really know about the deep sea. “We know only what we see in coastal, shallow living species,” he says. “In the deep sea and other places we haven’t explored yet, animals may have very different ways of doing things.”

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About the Author ()

Liz Roth-Johnson received her B.A. degrees in Molecular & Cell Biology and Music from UC Berkeley and recently finished her Ph.D. in Molecular Biology at UCLA, where she studied early development in fruit flies. Outside of the lab, Liz co-founded the K-8 science and engineering outreach program BEAM at UCLA and has worked extensively with the public outreach program Science & Food. Liz is delighted to be joining KQED Science as a 2014 AAAS Mass Media Fellow.