Scientists Discover ‘Suicidal’ Octopus Colonies Near Ocean Floor

Scientists discovered octopus colonies nearly 2 miles below the surface of the Pacific Ocean. (Phil Torres and Geoff Wheat / The Field Museum)Scientists discovered octopus colonies nearly 2 miles below the surface of the Pacific Ocean. (Phil Torres and Geoff Wheat / The Field Museum)

A team of scientists was exploring a rocky patch of ocean floor when they found something that shouldn’t have been there: octopuses – lots of them.

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About 100 miles off the Pacific coast of Costa Rica, scientists – including the Field Museum’s Janet Voight – used submersible vehicles to explore the Dorado Outcrop, a section of sea floor nearly 2 miles below the surface made from cooled and hardened lava from an underwater volcano.

The team had embarked on the mission hoping to collect samples of warm fluids that emerge from cracks in the rocks. Their observations were made both in-person and via hours of video taken by a drone. 

While they did get their fluid samples, the researchers did not expect to find octopuses moving in and out of the cracks. 

“When I first saw the photos, I was like, ‘No, they shouldn’t be there! Not that deep and not that many of them,’” said Voight, the Field’s associate curator of zoology, in a statement.

The discovery was a surprise because deep sea octopuses typically live in cold temperatures rather than warmer settings, which jump-start their metabolism and require more oxygen than the warm water can provide.

(Phil Torres and Geoff Wheat / The Field Museum)(Phil Torres and Geoff Wheat / The Field Museum)

Even stranger was that almost all of the octopuses observed were mothers, each guarding a clutch of eggs. For octopuses, the warm-water, low-oxygen environment is not an ideal place to live. Case in point: The octopus mothers showed evidence of severe stress, and none of their eggs had any signs of a developing embryo. Scientists concluded that the octopuses living in the warm water were in essence committing “suicide,” and that the unborn octopuses were all but “doomed.”

Why, then, did the octopuses take up residence in this unfriendly spot?

Based on the high volume of octopuses and eggs observed, researchers suspect there must be more octopuses living inside the rocks, where the water is cool and rich in oxygen. The crevices could be such a suitable environment for incubating eggs that the population had to spill over into the dangerously warm region outside the rocks, the scientists concluded, “like a gentrifying neighborhood expanding into a rougher part of town.”

Researchers also observed octopus arms poking out of cracks in the rocks, direct evidence that more octopuses were living inside. 

Findings from the research trip were published last month in the journal Deep-Sea Research Part I. The discovery is part of a growing body of research on octopuses, about which relatively little is known. Last year, a study involving scientists at the University of Illinois at Chicago found that octopuses – who are typically thought of as loners – can in fact congregate and socialize under the right conditions.

Voight said her team’s findings represent the first reports of octopuses at comparable depths in the section of ocean studied.

Contact Alex Ruppenthal: @arupp aruppenthal@wttw.com | (773) 509-5623


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