In the category of world’s best moms, the female Graneledone boreopacifica octopus is an admirable contender. The fastidious caregiver stands guard over her eggs for an incredible 53 months, three times as long as any other brooding species on the planet.

Octopus species typically spend about a quarter of their lives brooding. That means G. boreopacifica’s lifespan could be 16 to 18 years, making it the oldest cephalopod species -- a group that includes squid, cuttlefish, nautilus and octopus -- ever encountered.

According to the Monterey Bay Aquarium Research Institute, researchers first observed the record-breaking female octopus in 2007 while using a remotely operated vehicle, or ROV, to probe a deep-ocean canyon off California. They spotted the octopus clinging to a rocky ledge some 4,600 feet below the surface. Underneath her was a freshly-laid batch of eggs.  

The team returned frequently to the spot where the octopus had been seen, as she presented scientists with a rare opportunity to study the brooding habits of deep-sea octopus species. Every time researchers descended, they noticed the eggs getting a little bigger. This went on for four years. Details of the octopus appear in a study published Friday in the journal PLOS One.

"Each time we went down it was more of a surprise because we found her there again and again and again, past the point that anybody expected she'd persist,” Bruce Robison, a researcher at the Monterey Bay Aquarium Research Institute, which led the study, told The BBC. "It got to be like a sports team we were rooting for. We wanted her to survive and to succeed."

The last time the researchers looked, in October 2011, the octopus was gone. All that remained were 150 broken egg sacks.

In shallower waters, octopus mothers spend between one and three months brooding. But in cold deep-sea environments, where temperatures hover just a few degrees Fahrenheit above freezing, metabolic processes slow down.

Before scientists conclude that all deep-sea octopus species brood for extended periods of time, researchers would need to find other examples of this behavior having taken place. There is some speculation that the long brooding period of the female G. boreopacifica observed in California was an anomaly.

Here is video footage of the world’s longest-living octopus, posted to YouTube by the Monterey Bay Aquarium Research Institute: