An octopus living off the coast of California has set a record for motherly devotion, spending four and half years patiently guarding her eggs and nurturing them until they hatched, researchers say.
Marine scientist at the Monterey Bay Aquarium Research Institute first spotted the female octopus in 2007 from their submersible craft during surveys in the Pacific Ocean's Monterey Canyon.
She was making her way to a known brooding site, they said, to glue her eggs to a rock face more than 4,500 feet beneath the ocean's surface.
"No one had ever had the good fortune to come upon the beginning of a brooding period," says Bruce Robison of the institute.
Writing in the journal PLOS One, the researchers told of diving to the same spot 18 times over the course of four and a half years, finding the octopus -- recognizable by distinctive scars, possibly the result of fending off predators after her eggs -- in the same spot each and every time.
The octopus and her eggs were still there during a September 11 dive, but then in October another dive found her gone, with empty egg cases showing her young had hatched.
Because the young spend such a long period within their eggs, when they hatch they emerge as fully developed miniature adults and are already capable of hunting for small prey and surviving on their own.
The mother's devotion to her eggs may have been the final act of her life, Robison said, noting that the egg brooding period can occupy as much as the last quarter in the life of a female octopus.
She was never observed away from her egg clutch, he said, and probable never ate during her 53-month vigil.
"Everything we know suggests she probably didn't eat," Robison said.
Octopuses typically experience a single reproductive period after which they die.
The frigid temperature in the deep sea -- around 37 degrees Fahrenheit at the depths where the eggs are laid -- is likely a significant factor in the extraordinarily long brooding time, Robison said.
"The low temperature slows everything down," he said. The resulting low metabolism rate means the mother can survive with little or even no food as she protects her eggs and bathes them in oxygenated seawater.
The 53-month period is now the record for egg brooding in the animal kingdom, the researchers said, surpassing the previous record of 20 months by a species of giant red shrimp.
