Longest egg-brooding period

During a study conducted by California's Monterey Bay Aquarium Research Institute spanning 2007–2011, observing animals in the Monterey Canyon via remote-controlled viewing apparatus, a female deep-sea octopus belonging to the species Graneledone boreopacifica was observed clinging to a wall 4,600 ft deep. The first time that she was seen there was in May 2007, less than a month after she had laid a batch of eggs, attached to the wall, and each time that she was subsequently viewed during the next four years she was still there, while the young octopuses developed inside the eggs. She was last viewed there in September 2011; a month later, she was gone and the egg cases, roughly 160 in number, were empty, confirming that the eggs had hatched. Consequently, she had been brooding her eggs continuously for 53 months (almost four-and-a-half years) – the longest brooding period ever recorded for any octopus (or indeed, any animal species).

Mother octopuses are known to brood their eggs, caring for them very protectively until they hatch, which in shallower water normally takes 1-3 months, but virtually nothing had been recorded about brooding activity in deepsea octopuses until this very remarkable series of observations.