There is a new contestant for best mother in the world. She has eight arms, is slimy and fought off predators while not eating to take care of her soon-to-be little ones for four and a half years.

Researchers at the Monterey Bay Aquarium Research Institute in California first spotted the octopus in 2007 about 1,400 metres below the surface of the water in Monterey Canyon. When the remote-controlled submarine returned a month later, she had about 160 eggs attached to a rock.

For most shallow-water species this period is about one to three months, but this was the first opportunity to study an octopus in deeper water.

Researchers kept returning to the site and as they describe in the video below, weeks turned into months and months turned into years. They knew it was the same octopus, who they nicknamed Octomom, because of specific scars. As the months dragged on the octopus grew weaker, possibly because octopi usually never leave their eggs – not even to feed. Octomom would shift slightly, but would always stay over the eggs as she fought off crabs and turned from purple to white. Then one day, when the researchers returned she wasn't there. Only the egg cases remained. 

"At 53 months, it is by far the longest egg-brooding period ever reported for any animal species," reads the abstract of the study published Wednesday in the journal PLOS ONE. "These surprising results emphasize the selective value of prolonged embryonic development in order to produce competitive hatchlings. They also extend the known boundaries of physiological adaptations for life in the deep sea."

The longest egg brooding for any species on Earth before this was 14 months. The researchers suggest because it is cold, dark and dangerous in deep water, babies have to spend more time developing so they are better prepared to deal with the harsh realities of life.

Octopi reproduce only once during their lifetime and then die and rarely live more than two years.

But this presents an evolutionary challenge. "The trade-off within the reproductive strategy of deep-living octopods is between the mother's ability to endure a long brooding period and the competitiveness of her hatchlings," notes the paper. "Graneledone boreopacifica produces hatchlings that are very highly developed, which gives them the advantage of a high potential for survival."