In the depths of the Pacific, off the coast of California in the United States, at a depth of about 3,000 meters, a remarkable natural landscape lies hidden. The area is known as a mighty home for octopuses, where thousands gather to exploit the natural whirlpools that form there. Heat seeping through the cracks of hydrothermal vents accelerates the hatching of their eggs.
A team of scientists near Monterey, along the central California coastline, has documented the largest hatchery of its kind. Thousands of octopuses cluster in a natural whirlpool to mate, nest, and safeguard their eggs, a finding detailed in a study published by Science Advances.
Pearl octopuses, Muusoctopus robustrus, typically solitary marine animals, gather on the seabed around this site because the heat from a dormant submarine volcano filters through fractures. They use this warmth to quicken the development of their eggs.
There are clear advantages to settling in this natural whirlpool, according to Janet Voight, an octopus biologist at the Chicago Field Museum of Natural History and co author of the study.
This nesting site was first identified in 2018 by researchers from the Monterey Bay National Marine Sanctuary and other institutions. A remote controlled underwater vehicle helped observe a community of about 6,000 octopuses nesting at a depth just over 3,000 meters.
It was a striking sight. Thousands of pearl octopuses were seen lying upside down with their legs maneuvering to ward off predators and to turn their eggs for improved water and oxygen flow, explained Andrew DeVogelaere, a marine biologist at the National Oceanic and Atmospheric Administration.
mothers die fast
Over three years, the area was monitored to understand the brood cycle, tracking the developmental stages of eggs in 31 nests and the inevitable losses of mothers who guard the nests and are not fed during nesting. The researchers noted that after the young depart the nest and disperse in the dark, mothers who remain and are never fed perish rapidly.
View of the Octopus Garden MBARI
Further analysis showed that the nest’s warm temperature significantly reduced the time needed for eggs to hatch, thereby lowering the risk from hungry snails, shrimps, and other predators.
Eggs in this region hatch in about 21 months, a stark contrast to the four years or more required by other known deep sea octopuses. Cold water typically slows metabolism and embryonic development while shortening life in the deep sea, yet in this site the warmth appears to speed up these processes, said a marine biologist from a respected oceanographic institution who was not involved in the study.
A zoologist from the Smithsonian National Museum of Natural History, not part of the research, praised the team for collecting such detailed data on a remote location. The findings suggest these octopus gardens may be common and vital features of deep-sea ecosystems, with much still to learn about them.
Reference work: Science Advances, listing the study details and outcomes.
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