Secret garden: Why thousands of octopuses visit the same deep sea area each year

Researchers have finally discovered why thousands of deep-sea octopuses have been seen migrating to an underwater location known as the “Octopus Garden” off California’s coast. 

A collaboration between MBARI, the Monterey Bay National Marine Sanctuary, and other institutions reveals that the site serves as a special mating and nesting ground for the creatures.

The Octopus Garden 

Situated about two miles beneath the ocean’s surface near the base of Davidson Seamount, the Octopus Garden is warmed by deep-sea thermal springs. 

This warmth speeds up the development of octopus eggs, offering a shorter brooding period that seems to enhance the hatchlings’ survival odds. 

“Thanks to MBARI’s advanced marine technology and our partnership with other local researchers, we were able to observe the Octopus Garden in tremendous detail, which helped us discover why so many deep-sea octopus gather there,” said study lead author Jim Barry, a senior scientist at MBARI.

“These findings can help us understand and protect other unique deep-sea habitats from climate impacts and other threats,” 

The pearl octopus 

Interestingly, the site is swarming with a specific octopus species, Muusoctopus robustus. This species is referred to as the “pearl octopus” by MBARI researchers due to their iridescent nesting appearance from afar. 

Detailed studies with MBARI’s ROV Doc Ricketts reveal that these octopuses flock to this site exclusively for reproduction, without evidence of feeding or intermediate-sized individuals.

The discovery of “shimmering” waters by NOAA and Nautilus Live initially hinted at the presence of thermal springs. 

Subsequent studies confirmed that octopus nests are strategically positioned near hydrothermal springs, where water temperatures are much warmer compared to the surrounding deep-sea waters.

Accelerated reproduction 

The prolonged egg incubation periods typically seen in deep-sea octopuses due to frigid temperatures was also studied. Surprisingly, at the Octopus Garden, pearl octopus eggs hatched within two year. This is a considerably shorter time frame than the anticipated five to eight years. 

This accelerated hatching is attributed to the warmth from the thermal springs, suggesting its crucial role in ensuring the species’ reproductive success in such challenging environments. “By nesting at hydrothermal springs, octopus moms give their offspring a leg up,” said Barry.

Biological hotspot

While these congregations enhance octopus reproduction, they also invite scavengers and predators. The death of the octopuses post-reproduction provides a veritable feast for these scavengers. This, in turn, creates a unique ecosystem around the nesting sites.

This fascinating site is part of the protected Monterey Bay National Marine Sanctuary. Past explorations by MBARI revealed an abundance of marine life, which further confirms the need for conservation. 

“Essential biological hotspots like this deep-sea nursery need to be protected,” said Barry. “Climate change, fishing, and mining threaten the deep sea. Protecting the unique environments where deep-sea animals gather to feed or reproduce is critical, and MBARI’s research is providing the information that resource managers need for decision-making.”

The research was funded as part of the David and Lucile Packard Foundation’s long-term support of MBARI’s ocean research and technology.

More about the pearl octopus (Muusoctopus robustus)

The depths of our oceans hide a myriad of mysteries, many of which have yet to be fully understood or even discovered. Among these enigmas is the elusive deep-sea octopus known as Muusoctopus robustus.

With its distinct appearance and understudied habitat, this octopus piques the interest of marine biologists and enthusiasts alike. In this article, we’ll delve into the unique features and life of the Muusoctopus robustus.

Physical features

The Muusoctopus robustus boasts a gelatinous body that helps it navigate its deep-sea surroundings. While many octopuses have a soft, malleable physique, the density of the robustus is particularly notable. It is this very trait that grants it the name “robustus.”

Another significant feature is its lack of an ink sac. Unlike their shallower water counterparts, which use ink as a defense mechanism, deep-sea octopuses such as Muusoctopus robustus do not have this ability. This is possibly due to the lack of light in their habitat, rendering the ink ineffective.

Habitat and distribution

Muusoctopus robustus thrives in the deep waters of the Pacific Ocean, with sightings primarily around the northeastern parts of the Pacific. The depth they inhabit ranges from 500 to 4,000 meters below the surface. Here, light scarcely penetrates, temperatures drop significantly, and the pressure increases dramatically. It’s a testament to the adaptability of this species that they’ve evolved to not just survive but thrive in such extreme conditions.

Diet and predation

Feeding primarily on small crustaceans, shrimps, and other tiny deep-sea creatures, Muusoctopus robustus employs a stealth approach. Using its eight tentacles, it can effectively capture its prey in the blink of an eye. While it sits at the top of its food chain in its habitat, larger deep-sea predators could potentially pose a threat, although direct evidence remains scant.

Reproduction and lifecycle

Like other octopuses, Muusoctopus robustus reproduces by laying eggs. Deep-sea octopuses generally tend to lay fewer eggs than their counterparts in shallower waters, but these eggs are usually larger.

The mother guards her clutch until they hatch, a period during which she might not feed at all. The lifespan of Muusoctopus robustus, like many deep-sea creatures, remains a topic of research. However, octopuses generally have shorter lifespans, often ranging from one to a few years.

Conservation and human interaction

Given its deep-sea habitat, human interaction with Muusoctopus robustus remains limited. However, as deep-sea exploration and industries such as fishing or oil drilling expand, the potential for disturbances in their environment grows. Currently, there’s no specific conservation status for this species. As with many marine creatures, protecting their habitats from pollution and over-exploitation remains crucial.

Muusoctopus robustus serves as a reminder of the myriad mysteries our oceans continue to hold. As we journey further into understanding this fascinating creature, it underscores the importance of ocean conservation and the interconnectedness of marine life.

The deep-sea, although remote, impacts us all. Species like Muusoctopus robustus play their part in the vast tapestry of marine biodiversity.

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