In 2007 a remotely operated vehicle operated by the Monterey Bay Aquarium Research Institute found a female Graneledone boreopacifica clinging to a vertical rock face at about 1,400 metres, guarding a clutch of eggs. Distinctive scarring made her individually identifiable on later dives.
Bruce Robison and colleagues returned repeatedly. Over 53 months she remained on the same eggs, growing paler and losing bulk, and was never observed eating, though crabs and other potential food passed within reach. When the site was last visited the eggs had hatched and she was gone. Published in 2014, the 53-month brood exceeds any other known egg-brooding period in the animal kingdom.
The cold explains part of it: at roughly three degrees Celsius, development is slow, and the long brood yields unusually large, well-developed hatchlings that skip a planktonic stage. It is not certain she took no food at all across four and a half years, since dives sampled only a fraction of the time, and whether such extreme brooding is typical for the species rests on this one continuous record.