Baby octopus from likely new species seen hatching at rare low temperature, deepwater nursery

Scientists say they have found only the third known octopus nursery, in deep water offshore from Costa Rica.

The new brooding site is 2800m below the surface of the Pacific Ocean at a low-temperature hydrothermal vent.

During the same voyage the scientists, who were onboard the Schmidt Ocean Institute ship Falkor, also proved another previously identified site was an active octopus nursery, the institute said.

That was at a place called Dorado Outcrop, more than 3000m below the surface. It was discovered in 2013, and had been the first place where female octopus were seen to be gathering to brood eggs.

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At that time, about 100 female octopuses had been on the outcrop, which was an area about the size of a football field.

While no developing embryos had been seen in 2013, the discovery had shocked experts because octopuses had been considered solitary creatures, the institute said on its website.

Octopuses had been seen fighting over territory or mating towards the end of their lives. Females were known to brood their eggs alone in rocky crevices, dying after their eggs hatched.

The lack of embryos seen in 2013 at Dorado Outcrop had raised the possibility conditions at the site might not support octopus growth.

But during the latest expedition, scientists using a remotely operated underwater vehicle had seen octopuses hatching, the institute said.

They were thought to be a new species of Muusoctopus – a small to medium-sized genus without an ink sac.

At Dorado Outcrop the temperature of the hydrothermal fluids was about 12C, compared to the surrounding bottom water temperature closer to 2C. At the newly-discovered nursery site the temperature was 7C.

The new findings reinforced an idea that some species of deep-sea octopus sought out low-temperature hydrothermal vents to brood their eggs, the institute said.