Hidden among the many weird creatures that lurk in the deepest depths of our planet is an octopus nursery, where thousands of brooding eight-legged mothers nestle in the warmth of volcanic vents.
This spectacular ‘Octopus Garden’ is described for the first time in the journal Science Advances.
Nearly 6,000 octopuses (Muusoctopus robustus) have been discovered in their 2.5 hectare (6.2 acre) Garden. Scientists think they have sought out the warm hydrothermal springs of an extinct volcano, lying near the bottom of the ocean far off the coast of California, USA.
At 3,200m (10,500ft) deep, the incredibly cold environment does not make reproduction easy. According to the study, reproduction rates for species in environments near 0°C (32°F) can be 4 to 33 times slower than those in 10°C (50°F) waters. Even near the hydrothermal vents, the temperature could get as low as 3°C (37.4°F).
For these octopuses, reproduction can be as lengthy as several years. Cold waters can increase this time by slowing down their metabolism and the development of embryos. However, if the creatures can get more warmth the reproduction process speeds up – reducing the risk of predation or injury to the baby.
The Octopus Garden, located on the cliff edges of the Davidson Seamount, was first discovered in 2018. Only a few deep-sea octopus nurseries have ever been found – and this one is the largest known collective of octopuses on the planet.
Since its discovery, scientists have been desperate to learn why the cephalopods have chosen this location. The team behind this study from Monterey Bay Aquarium Research Institute (California, USA) examined the Octopus Garden through temperature and oxygen measurements. They also took high-resolution images and time-lapse videos.
The Garden was initially difficult to see, given that the boundary between the cold seawater and warm fluid from the vents creates a shimmering mirage.
The 5,718-strong octopus population includes 4,707 nesting females. Octopuses die after reproducing – so they come here to “mate, nest, and die” according to the paper.
Main image credit: MBARI
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