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Never-Before-Seen Colony of 1,000 Brooding Octopuses Found Off California Coast

The deep sea creatures are raising their eggs on the Davidson Seamount in Monterey Bay National Marine Sanctuary

smithsonian.com

When researchers aboard the Exploration Vessel Nautilus spot a cool squid or octopus, it can break the internet. But last week, the research vessel, which streams many of its discoveries live, hit the eight-legged jackpot during an exploration of the Davidson Seamount off the coast of Monterey, California. Not only did their ROV capture images of a super-cute dumbo octopus, but they also found something truly spectacular: a breeding colony of 1,000 rare deep-sea octopuses. (No, it’s not octopi.)

The Davidson Seamount inside the Monterey Bay National Marine Sanctuary is essentially an underwater mountain jutting 7,480 feet off the ocean floor. The massive structure is 26 miles long and eight miles wide. Even still, the summit is submerged in 4,100 feet of water making it difficult to study the deep-sea habitat. According to Nautilus, the seamount and region around it has been mapped extensively before and the ship visited the mount 12 years ago. However, there is a deepwater region of basaltic reef on the southeast side of the mount that had been less explored that the team decided to focus on this time around.

What they found toward the end of 35 hours of exploration was an unprecedented colony of Muusoctopus robustus, a purple-ish deep sea octopus species.

“We went down the eastern flank of this small hill, and that’s when—boom—we just started seeing pockets of dozens here, dozens there, dozens everywhere,” Nautilus chief scientist Chad King tells Bittel. Most of the octopuses were clinging to the rock in an inverted positions the animals take while protecting their eggs. “Out of that 1,000, we might have seen two or three octopuses that were just swimming around. So I’d say almost 99 percent were brooding.”

King also says the crew could see shimmers in the water, indicating that hotter water was seeping out of the seamount, though the ROV was not able to get close enough to measure the temperature.

“This has never been discovered on the West Coast of the U.S., never in our sanctuary and never in the world with these numbers,” King tells Muna Danish at NPR station KQED. “I’ve never in my career come across something like this, where these could potentially be nursery habitats, and another extremely important reason why we need to protect this area.”

This is only the second breeding colony of octopuses in the genus Muusoctopus discovered. The other colony was found by a deep sea submersible off the Pacific Coast of Costa Rica called the Dorado Outcrop in 2013, though a study on them was only released in April. That colony consisted of around 100 animals most of which were also brooding.

But in a sad twist, the researchers also found that the mothers had chosen a rotten place to raise their babies. While warm water flows can help octopus embryos develop, the spot on the outcrop was a little too warm and low oxygen. After examining almost 200 eggs using their ROV, the team found only one with a developing embryo inside.

KQED’s Danish reports the Nautilus crew is excited to return to the site to explore more, but technical problems have grounded their ROV. They now hope to secure more research funding to figure out why the octo-mamas chose that spot. It could be because of the warm water, a certain mineral in the area, a higher oxygen content, or just because it was the cleanest rock to attach their eggs to.

But that’s a mystery for another day.

About Jason Daley

Jason Daley is a Madison, Wisconsin-based writer specializing in natural history, science, travel, and the environment. His work has appeared in Discover, Popular Science, Outside, Men’s Journal, and other magazines.

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