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A steadfast little octopus living in the deep waters of Monterey Bay has set an extraordinary record of animal motherhood, laying her clutch of eggs and brooding them nonstop for 53 straight months — apparently without pause for food or rest.

No creature in the world, large or small, has ever approached such a feat, say biologists who watched over the octopus with cameras in an unmanned submarine from Monterey Bay Aquarium Research Institute.

The deep-water octopus was a small one, with a mantle barely 8 inches from stem to stern. But she made up in staying power what she lacked in size, said Bruce Robison, the institute biologist who observed the mother again and again as she protected her eggs on a rock in the Monterey Submarine Canyon.

Robison, who has been studying the ecology of the canyon’s midlevel waters for 25 years, seven years ago spotted a female octopus moving slowly across the ocean floor toward a rocky outcrop 4,600 feet beneath the surface where he’d noticed other females brooding their eggs.

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A distinct pattern of scars on this female’s mantle identified the octopus, and a month later when Robison returned with his underwater vehicle he spotted her again, this time guarding a clutch of newly laid eggs attached to the same rock.

“This was a chance to watch the whole brooding process,” Robison said. “It was a fluke. No one before ever had a chance to see anything like it, so it was kind of bootleg science, but we decided to watch her again and again.”

Octopus eggs develop extraordinarily slowly in cold water — it was 37 degrees where the eggs were laid — and this mother was on duty every time the scientists checked in.

“We measured her with lasers,” Robison said, “and each time we saw her eggs growing larger and larger until we could see her babies developing inside the transparent eggs. We could watch her sweeping water over them with her arms to carry oxygen in the fresh seawater into their permeable egg cases, and we watched her brushing silt away to keep the eggs clear.

“During that whole time we never saw her leave the eggs once,” said Robison, whose team would watch the octopus closely for an hour or more each time they visited. “We never saw her eat anything, and she paid no attention to the crabs and shrimp swimming by, except when she pushed them away with her arms because they were predators.”

On Robison’s final observation, the mother was gone, and he never saw her again. The eggs, which she had attached to the face of the rock, were now only empty cases — each one about the size of a shrunken olive.

He never saw the hatchlings, but he counted the egg cases and figured there must have been 160 babies, all of which had swum off.

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