Researchers have located the planet's largest known octopus nursery deep off the Californian coast, documenting 5,718 animals in 2.5 hectares and estimating about 20,000 around Davidson Seamount.
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Researchers → locate → Seamount
Known as the Octopus Garden, the nursery is located about 10,500 feet below the surface off Central California.
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nursery → know → California
According to a statement released by the Monterey Bay Aquarium Research Institute (MBARI) on August 23, 2023, monitoring confirmed that pearl octopuses migrate to the site for mating and nesting.
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octopuses → accord → mating
The species was identified as Muusoctopus robustus, known to researchers as the pearl octopus.
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species → identify → octopus
The nursery is situated on a small hill near the base of the Davidson Seamount, which is an extinct volcano located 130 kilometres southwest of Monterey, California.
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which → situate → Monterey
The large concentration first drew attention in October 2018.
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concentration → draw → October
Researchers from the Monterey Bay National Marine Sanctuary, NOAA, Ocean Exploration Trust, and collaborators, working aboard the E/V Nautilus, observed thousands of octopuses gathered on a rocky rise near the seamount.
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Researchers → work → seamount
The position of the animals helped researchers understand exactly what was happening in the section of the ocean.
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what → help → ocean
Many of the octopuses were upside down, with their arms positioned around their bodies, a posture that is associated with females protecting and incubating their eggs.
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females → position → eggs
The species was identified as Muusoctopus robustus, known to researchers as the pearl octopus.
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species → identify → octopus
They exhibit a pale purple colouration.
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They → exhibit → colouration
According to MBARI, the animal is approximately the size of a grapefruit and occurs in the northeastern Pacific Ocean, from Oregon down to Baja California.
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animal → accord → California
The institute has observed the species at depths between 2,300 and 3,600 metres.
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institute → observe → metres
After the initial discovery, researchers began a prolonged investigation to determine why so many animals were concentrated at that point.
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animals → begin → point
For three years, the institute and its partner institutions employed cameras, sensors, remotely operated vehicles and other equipment to observe the behaviour of octopuses and the environmental conditions of the nursery.
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institute → employ → nursery
Doc Ricketts, a remotely operated vehicle from MBARI, played a central role in the research.
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Ricketts → operate → research
The team conducted 14 dives with the ROV during which scientists found adult males and females, developing eggs and hatchlings.
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scientists → conduct → eggs
No individuals of intermediate size or evidence of feeding were observed at the site.
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individuals → observe → site
These observations indicated that the octopuses gather there specifically to mate and nest.
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octopuses → indicate → ?
The size of the concentration was measured using a combination of photographs and detailed mapping of the seabed.
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size → measure → seabed
The LASS system, installed on the Doc Ricketts ROV, allowed high-resolution images to be produced and a photomosaic of the region to be assembled.
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photomosaic → instal → region
In this survey, researchers documented 5,718 octopuses in just 2.5 hectares at the centre of the Octopus Garden.
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researchers → document → Garden
The slight elevation where the nursery is located occupies approximately 333 hectares, or 823 acres.
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nursery → locate → hectares
Based on the surveys conducted, the team calculated that the total population could easily exceed 20,000 individuals.
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population → base → individuals
It is the thermal conditions of the area that explain why this small area attracts so many animals.
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area → explain → animals
However, in the crevices and fissures used by the octopuses, water warmed by the hydrothermal vents reaches nearly 11°C.
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water → use → C
The initial researchers observed a "sparkling" appearance in the water, caused by the mixture of hot and cold water.
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researchers → observe → water
Subsequent investigations confirmed the existence of hydrothermal vents and showed that the nests are clustered precisely in the fissures bathed by the warmer water emerging from the seabed.
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nests → confirm → seabed
Females migrate to the Octopus Garden in search of warm locations where they can nest.
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they → migrate → locations
Octopuses are ectothermic animals, and the cold deep waters reduce their metabolism and slow embryonic development.
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waters → reduce → development
At temperatures close to zero found in the abyssal environment, researchers expected that the pearl octopus's eggs would need five to eight years or even longer to hatch.
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eggs → find → years
But the temperature in these locations revealed a different outcome.
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temperature → reveal → outcome
Using 4K imaging and features like scars to recognise the animals, scientists tracked their clutches and found that the eggs hatched in less than two years.
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eggs → use → years
This acceleration was attributed to the heat from he hydrothermal vents, which increases the mothers' and embryos' metabolism.
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which → attribute → metabolism
Females migrate to the Octopus Garden in search of warm locations where they can nest.
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they → migrate → locations
Each one lays a clutch of approximately 60 elongated eggs and covers the embryos with her body while they develop.
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they → lay → body
Interestingly, the nursery also serves as a food source for other species.
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nursery → serve → species
As is typically the case with cephalopods, both male and female pearl octopuses die after reproduction.
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octopuses → die → reproduction
Most mother remain alive until the eggs hatch, though some exhaust their reserves before development is complete.
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development → remain → reserves
Their carcasses are consumed by various organisms from the area.
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carcasses → consume → area
…and 3 more, not listed.
