One species of deep-sea octopus broods over its eggs for more than four years, longer than any other known species.
Graneledone boreopacifica, a small species of octopus, has a body less than four inches long. They are found living deep beneath the surface in both the Atlantic and Pacific Oceans, and are one of the most common varieties of the animal in the northeastern Pacific.
Monterey Bay Aquarium Research Institute (MBARI) researchers witnessed one of the animals brood over her young for an astonishing 4.5 years. During this entire period, the mother octopus protected her developing eggs from predators, and kept them clean.
Some observers are referring to the species as "the mother of the year" for this long-term nurturing. This behavior represents a balance in evolution, between protection for the defenseless young and the biological needs of the mother, who eats little during this time.
"Midwater 1," a site in the Monterey Canyon, has been the location of regular dives, happening every few months, by researchers from MBARI. These investigations have taken place over the last 25 years.
During one of these dives, in May 2007, divers discovered a female clinging to a ledge, 4,600 feet beneath the surface of the water. This was the first time researchers spotted the animal at that location. The animal was seen, over the course of 18 dives, still caring for her eggs. During that time, the mother became frail, and her skin lost color. Despite little feeding as she cared for her brood, the animal showed little interest in shrimp and small crabs that passed near her. During one dive in September 2011, researchers saw the animal, still clinging to the rocky ledge. In a follow-up dive undertaken in October, she was gone, leaving behind the remains of broken eggs.
Octopus mothers usually die soon after raising their young, so it is likely the determined mother perished after successfully hatching a flock of offspring.
"This research suggests that, in addition to setting records for the longest brooding time of any animal, Graneledone boreopacifica may be one of the longest lived cephalopods (a group that includes octopuses, squids, and their relatives). Most shallow-water octopuses and squids live just a year or two," MBARI directors wrote in a press release.
Laboratory studies have found a correlation between colder temperatures deep under water and long brooding periods in octopuses. This new find would tend to lend credence to that theory.
Study of the octopus mother and the exceptional brooding period of the species was detailed in the journal Plos One.
