According to the Monterey Bay Aquarium Research Institute (MBARI), researchers have located the planet’s largest known octopus nursery 10,500 feet below the ocean’s surface off Central California. Named the Octopus Garden, the site hosts an estimated 20,000 pearl octopuses—scientifically identified as Muusoctopus robustus—that migrate to the thermal springs at the base of the Davidson Seamount to mate and nest.
Discovering the Octopus Garden Near Davidson Seamount
The massive concentration of deep-sea cephalopods first drew attention in October 2018. According to reports from the Monterey Bay National Marine Sanctuary, NOAA, and the Ocean Exploration Trust working aboard the E/V Nautilus, thousands of animals gathered on a rocky rise near the seamount. Davidson Seamount is an extinct volcano located 130 kilometers southwest of Monterey, California.
Researchers noted that many of the animals positioned themselves upside down with their arms folded around their bodies. According to MBARI, this posture is a clear indicator of females protecting and incubating their eggs.
How Hydrothermal Vents Accelerate Deep-Sea Development
Thermal conditions at the site explain why thousands of pearl octopuses congregate in the area. While normal water temperature at 3,200 meters sits at roughly 1.6°C, water warmed by hydrothermal vents in the nesting fissures reaches nearly 11°C, according to research data. This geothermal heat drastically cuts down incubation times.
Did you know? In freezing abyssal waters near zero degrees, researchers expected that the pearl octopus’s eggs would need five to eight years or even longer to hatch. Heat from the hydrothermal vents accelerates this process, allowing eggs to hatch in less than two years and reducing the embryos’ vulnerability to predators.
Each female pearl octopus lays a clutch of approximately 60 elongated eggs and broods them until hatching. Because brooding females do not eat, most die around the same time their young emerge, according to institute observations.
Measuring the Deep-Sea Population
For three years, MBARI and partner institutions deployed cameras, sensors, and remotely operated vehicles like the Doc Ricketts to study the site. Operating from the research vessel Western Flyer, scientists conducted 14 ROV dives to map the region.
Using the LASS system mounted on the Doc Ricketts, researchers assembled high-resolution photomosaics of the seabed. Within a 2.5-hectare area at the center of the nursery, scientists documented exactly 5,718 octopuses. Based on mapping the entire 333-hectare elevation, the research team calculated a total population exceeding 20,000 individuals.
Ecological Impact on the Abyssal Food Web
The nursery functions as an important resource for local marine scavengers. Post-reproductive carcasses left behind by adult male and female pearl octopuses provide substantial biomass for the surrounding community.
According to research findings, this localized food supply provides 72% more food to local scavengers—including ratfish, cusk eels, sea slugs, and anemones—than would otherwise be available outside the Octopus Garden.
Frequently Asked Questions
How deep is the Octopus Garden nursery?
The Octopus Garden is located approximately 3,200 meters, or 10,500 feet, below the ocean’s surface.
What species of octopus lives at the site?
The site is inhabited by Muusoctopus robustus, commonly known as the pearl octopus, which is a pale purple cephalopod about the size of a grapefruit.
Why do octopuses gather at this specific location?
According to MBARI, pearl octopuses migrate to the site to use the warmth from hydrothermal vents, which accelerates egg development and improves hatchling survival rates.
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