Who is the most selfless mother?

Graneledone boreopacifica is a species of octopus found in the Pacific and Atlantic Oceans, and the female of the species makes the ultimate sacrifice for her offspring: She guards her eggs for a very long time until she dies of hunger. A female observed in Monterey Canyon off the coast of California brooded her eggs for nearly four and a half years—a record in the animal kingdom. During this time the female never left her eggs unattended, even as her body began to waste away. The trade-off for this extremely long brooding time is that the hatchlings are very developed when they emerge and are able to hunt for prey and take care of themselves, thereby increasing their chances of survival. Since most octopuses live for only a few years in the wild, this species is most likely the longest-lived octopus. It’s not entirely clear how the octopus is able to maintain her vigil without any nourishment. Scientists believe the lack of activity drastically reduces metabolic demands, but in the end the process takes a huge toll on the mother: Over time she loses weight, her skin becomes loose and pale, and her eyes cloud over. Still she watches and waits, slowly dying so that her progeny can live.