The Hot Secret behind a Deep-Sea ‘Octopus Garden’

Thousands of deep-sea octopuses gather on the flanks of a seamount off California’s coast. But until recently, scientists weren’t sure why these otherwise solitary animals were congregating. New research suggests they are seeking warmth to help their babies hatch more quickly.

The Davidson Seamount’s “Octopus Garden” was discovered in 2018, when researchers onboard the Ocean Exploration Trust research vessel Nautilus were exploring a rocky spot on the seafloor that was about two miles below the surface. The team spotted a pair of octopuses through a camera on a remotely operated vehicle (ROV), says Amanda Kahn, an ecologist at Moss Landing Marine Laboratories and San Jose State University, who was on the Nautilus that day. After observing the pair for a bit, the operators started to lift the ROV off the rocks to move on—until they saw something unusual. “Up ahead of us were streams of 20 or more octopuses nestled in crevices,” Kahn says.

Octopuses are usually solitary, so it was immediately clear that something strange was happening. The researchers dropped…