Scientists solve mystery of why thousands of octopus migrate to deep-sea thermal springs

Advanced technology offers new insight into the ‘Octopus Garden’ off Central California, the largest aggregation of octopus on Earth

In 2018, a captivating discovery known as the “Octopus Garden” was made by researchers from NOAA’s Monterey Bay National Marine Sanctuary and Nautilus Live. They found thousands of octopuses nesting on the deep seafloor off the Central California coast. Over the following three years, a collaborative effort involving MBARI (Monterey Bay Aquarium Research Institute) and other institutions utilized advanced technology to study the Octopus Garden and uncover its mysteries.

A recently published study in Science Advances details the findings of this research. The team, consisting of scientists from MBARI, NOAA, Moss Landing Marine Laboratories, the University of Alaska Fairbanks, the University of New Hampshire, and the Field Museum, confirmed that the Octopus Garden serves as a nursery for deep-sea octopuses’ mating and nesting activities. This location is among a small number of known deep-sea octopus nurseries. The site’s unique feature is the presence of thermal springs that accelerate octopus egg development due to increased warmth. This shortened incubation period is believed to enhance the survival chances of octopus hatchlings.

The Octopus Garden, situated around 10,500 feet below the ocean’s surface on a hill near Davidson Seamount, an extinct underwater volcano off the Californian coast, contains a substantial number of Muusoctopus robustus, often referred to as pearl octopuses due to their appearance from a distance.

Through 14 dives using MBARI’s remotely operated vehicle (ROV) Doc Ricketts, the research team identified why pearl octopuses are drawn to this specific location. The presence of adult male and female octopuses, developing eggs, and hatchlings suggested that the area is exclusively used for reproduction. It’s a nesting site where octopuses gather for mating and raising their young, not for feeding.

The key factor that attracts octopuses to the Octopus Garden is the presence of hydrothermal springs that create warmer conditions within crevices and cracks, compared to the chilly ambient water at that depth. These warmer temperatures accelerate embryo development, resulting in a considerably shorter brooding period. This speedier development offers hatchlings a better chance of survival as it reduces their exposure to potential dangers.

The researchers estimated that the Octopus Garden might contain over 20,000 individuals in total, making it the most significant aggregation of octopuses on Earth.

Protecting such unique habitats is crucial, especially in the face of threats like climate change, fishing, and pollution. The insights gained from studying the Octopus Garden help in guiding conservation efforts and decision-making to safeguard these deep-sea environments and the life they harbor.

This study showcases the power of advanced marine technology in unveiling the secrets of the deep sea. The collaboration among research institutions has provided valuable knowledge about the behaviors and adaptations of deep-sea creatures, contributing to our understanding of Earth’s unexplored frontiers.