Even the clingiest helicopter parents ain't got nothin' on Graneledone boreopacifica, a deep-sea octopus that spends four and a half years sitting atop her eggs. Without a break. Or a meal. Until she literally drops dead.
Using a remotely operated vehicle (ROV), scientists at the Monterey Bay Aquarium Research Institute were able to observe a single female deep-sea octopus (Graneledone boreopacifica) over the course of 53 months as she guarded her clutch of 160 eggs. The details of the research were published this week, and have confirmed that with a brood time of around four and a half years, this octopus species now holds the record for the longest brooding period of any animal on the planet.
The record-breaking mama was first observed in May 2007, having laid her eggs on a sheer rock face in the Monterey Submarine Canyon off central California. Scientists returned to the site (1,397 meters deep) every few months, and each time they found the same female with her arms wrapped protectively around her eggs. She never once budged from her spot – even as the giant ROV with glaring spotlights gently lifted her arms out of the way to measure the size of her eggs.
During a previous research expedition, an ROV was used to vacuum up a female of the same species together with her eggs, allowing researchers to discover that the yolks of the eggs were unusually large. Large yolks allow the young octopuses to stay in the egg longer, emerging as fully mature miniature versions of an adult, and bypassing the development period that many octopuses go through as they float around as immature plankton.
The previous egg-guarding record-holder was another deep-ocean octopus, Bathypolypus arcticus, who watched over her eggs for 14 months until they hatched. These brooding times put other animals to shame, with the emperor penguin (which holds the title of longest brooding period for a land-based animal) topping out at a paltry two months.
It’s likely that the female deep-sea octopus observed in this study never once left her eggs during the brooding period ... and not leaving also probably meant not eating (scientists did offer her pieces of crab meat using the ROV’s robotic arm, which she refused). This is not surprising, of course, since most octopus species don't eat while guarding their eggs. But if this was the case here, it would mean that this extreme octomom did not have a single meal for almost five years!
To add insult to injury, she likely died as soon as her offspring hatched in the fall of 2011. As is normal for her kind, the entire brooding process is essentially a slow death for the female. The researchers noted how she transformed from a healthy colour and size to a shriveled old crone over time, with "loss of skin texture, cloudy eyes, slack skin, and a loss of pigmentation."
So why would an octopus mother go to such extreme parenting lengths, making the ultimate sacrifice for her offspring?
The advantage of investing so much time in your eggs has to do with hatchling survivability. After fattening up for more than four years, the young octopuses emerge from the egg able to fend for themselves, drastically increasing the likelihood that they survive the first few years of life. Water temperature almost a mile under the ocean’s surface is just three degrees Celsius, cold enough to slow down the metabolism of the protective mother and her embryos, allowing them the extra time they need to mature into resilient little scrappers.
If the normal rule applies to this species as it does to most octopods, the life expectancy of the hatchlings is around three times the length of the brooding period, or nearly 15 years. This would make Graneledone boreopacifica the longest-lived of all cephalopods.
"The ultimate fate of a brooding female octopus is invariably death, but in this first example from the deep sea, brooding also confers an extension of adult life that greatly exceeds most projections of cephalopod longevity," suggested the authors.
The only bad news in our mom-hero story (aside from the death of the protagonist) is, rather predictably, the role of humanity. “Because the brooding period is temperature dependent, the results also provide a caution about the potential consequences of our changing climate,” warned Bruce Robison, lead author on the study. If ocean temperatures at these depths begin to rise, the water in the canyon might not be cold enough to sustain these tenacious parents.
Aside from starving to death and not moving for four years, it seems a tragedy to add brood failure to the list of trials these poor moms have to endure.
Top header: Anjan Chatterjee, Flickr
