A deep-sea octopus has been discovered to brood its eggs for four years and five months, doubling the longest time ever recorded for any animal.

According to BBC News, the researchers used a robotic submarine for their new study, published in the journal PLOS One. They were able to identify the octopus from a distinctive scar under the armpit of one of the animal's eight tentacles. The previous brooding record belonged to the giant red shrimp at 20 months.

Dr. Bruce Robison, of the research at the Monterey Bay Aquarium Research Institute (MBARI), and his team first saw the mother octopus in May 2007 1.4km below the surface of the Pacific Ocean, off the coast of California.

"The first time that we dropped back down... and realized that she had gone up and laid a clutch of eggs, it was very exciting," Robison told BBC News. "We knew that we had the beginning.

"No-one had ever had the good fortune to come upon the beginning of a brooding period."

After spotting the octopus on the way to her eggs at a popular brooding place, the researchers noticed in Oct. 2011 that the egg casings were empty and the mother was nowhere to be found. As is common among octopus, the mother likely died after the eggs hatched, since the process typically takes up the last quarter of their lives.

"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," Robinson said. "It got to be like a sports team we were rooting for. We wanted her to survive and to succeed."

The researchers said the frigid three-degrees-Celsius temperature where the octopus brooder her eggs was likely vital to the entire process.

"They're exceptionally good mothers," Kerry Perkins, an aquarist at the Sea Life aquarium in Brighton, told BBC News, noting the octopus probably did not eat anything while her eggs were brooding. "It is very, very cold water and they're not moving much, so their metabolic rate would be pretty low - but still, you'd think in four and a half years you'd probably have to have a snack at some point."