Ocean mystery solved: Scientists discover why thousands of octopuses congregate off the Monterey coast

By Christian Balderas

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    MOSS LANDING, California (KSBW) — The deep sea octopus typically leads a solitary life. That’s why in 2018 marine scientists were shocked to discover thousands of octopi near the Monterey Bay.

After three years of research, they now think they know why.

In a new study published in Science Advance 2023, researchers suggest that the octopi —found on the base of Davidson Seamount, an extinct underwater volcano 80 miles off the coast of Moss Landing — migrate to the area solely to mate and nest.

Researchers counted 6,000 octopi and estimate there are more than 20,000 in the area they now call Octopus Garden.

“It was a moment where we saw it and we all took a breath. We all got excited together and we just started babbling about what could this mean. Why were they there,” Amanda Kahn, an ecologist for Moss Landing Marine Laboratories and San Jose State University.

In 2018, Khan was one of multiple marine scientists who discovered the garden while on an expedition for the Monterey Bay National Marine Sanctuary to look for sponges — not octopus.

“There are some things that you see and you immediately know is special,” Khan said.

The octopus found here, specifically known as the Pearl Octopus, migrates to the hypothermal springs.

Compared to the rest of the frigid deep sea, the water found in the crevices along the seamount, where the octopi are nesting, is the perfect temperature for incubation at 51 degrees Fahrenheit.

“We were able to measure their metabolism and we found that their metabolism speeds up in that warmer water and that means that their eggs develop faster than they would in otherwise frigid water,” Kahn said.

Normally, in the deep sea, the octopus’s eggs take five to eight years to hatch, but at Davidson Seamount, they take less than two.

It’s a discovery that Monterey Bay Aquarium Research Institute was made by recent advances in subsea technology,

“We sit in the ship with pilots flying this tethered vehicle two miles below the surface. They’re controlling it and they’re able to drive this Volkswagen-sized, remotely operated robot to a distance of about a foot or two away from these octopi,” Jim Barry of MBARI said.

Khan and Barry say research is still ongoing.

The Octopus Garden Garden is one of a handful of known nurseries, many of which are on thermal springs.

Barry told KSBW that a second group of octopus was found close to the garden and along the seamount; he’s in the midst of planning an upcoming expedition. Marine Scientists do not know how large that nursery may be.

Researchers from SJSU’s Moss Landing Marine Laboratories, MBARI, NOAA’s Monterey Bay National Marine Sanctuary, the University of Alaska Fairbanks, the University of New Hampshire and the Field Museum contributed to the research effort behind the study.

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