Scientists have observed a deep-sea octopus that brood its eggs for four and one half years-longer than any other known animal.
According to the researchers at the Monterey Bay Aquarium Research Institute (MBARI), the female kept the eggs clean and guarded them from predators, representing an evolutionary balancing act between the benefits to the young octopuses of having plenty of time to develop within their eggs, and their mother's ability to survive for years with little or no food.
Every few months for the last 25 years, a team of MBARI researchers led by Bruce Robison has performed surveys of deep-sea animals at a research site in the depths of Monterey Canyon and in May 2007, the researchers discovered a female octopus clinging to a rocky ledge just above the floor of the canyon, about 1,400 meters (4,600 feet) below the ocean surface. he octopus, a species known as Graneledone boreopacifica, had not been in this location during their previous dive at this site in April.
Over the next four and one-half years, the researchers dove at this same site 18 times. Each time, they found the same octopus, which they could identify by her distinctive scars, in the same place and as the years passed, her translucent eggs grew larger and the researchers could see young octopuses developing inside, while over the same period, the female gradually lost weight and her skin became loose and pale.
The researchers never saw the female leave her eggs or eat anything and it did not even show interest in small crabs and shrimp that crawled or swam by, as long as they did not bother her 160 eggs.
The last time the researchers saw the brooding octopus was in September 2011, but when they returned one month later, they found that the female was gone and the rock face octopus had occupied held the tattered remnants of empty egg capsules.
The study was published in the Public Library of Science (PLOS ONE).