This amazing pale purple Octomom off the coast of California brooded her clutch of eggs for four and half a years. That’s the longest known brooding period of any animal on the planet.
Female octopuses typically have a single reproductive period, and then they die. For shallow-water species, parental care lasts up to three months. The previous record holder for longest octopus brooding was the deep-living Bathypolypus arcticus: 14 months in the lab. But we know very little about deep-sea species in their natural habitat.
A trio of researchers led by Bruce Robison from Monterey Bay Aquarium Research Institute (MBARI) first met this deep-sea Graneledone boreopacifica mom in April 2007. They were surveying an isolated rocky outcrop about 1,397 meters (4,583 feet) deep in the Monterey Submarine Canyon using a remotely operated vehicle. They spotted her moving slowly on sediment nearby.
When they returned in May 2007, she was clinging to the vertical rock face, guarding a clutch of eggs she'd cemented on. The team knew it was the same devoted female over the course of 18 visits thanks to a distinct scar on the web between two arms, and their continuous growth indicated the clutch was the same. The developing young require lots of oxygen, so the female must continuously bathe the long eggs in fresh seawater and keep them from being covered with silt. At the same time, she must push away all would-be egg predators. Here she is hanging on in 2009.
"It went on and on, and we were just staggered," Robison tells Nature. "Every time we’d drop down to visit we’d say, 'This is the last time she’s going to be here.'" The eggs hatched between the team’s September and October 2011 trips -- when only empty egg cases were found (pictured below). Octomom’s clutch size was between 155 to 165 eggs, and the brooding period totaled 53 months. The work was published in PLoS One this week.
Because these young octopuses had so long to develop, they could swim and hunt soon after hatching, which increases their survival odds. The team spotted a few on the same rock later.
The trade-off with Octomom’s doting strategy is between her ability to endure the long brooding period and the competitiveness of her hatchlings. During the 53-month period, the researchers never witnessed her feeding; she grew paler and lost weight, her skin loosened and her eyes grew cloudy. Low temperatures (3 degrees Celsius) and her inactivity kept her metabolic demands low, and maybe she absorbed damaged eggs or nibbled on crabs photographed nearby.
The longest guarded incubation known for fish is five months by the Magellan plunder fish. For birds, the longest uninterrupted egg brooding goes to emperor penguins with two months. Then there are “live-bearing” species, whose embryos develop internally so that when they’re born, they’ve basically mini versions of the adults: Elephants gestate for 20 to 21 months, frilled sharks carry embryos for 42 months, and the gestation period of alpine salamanders is 48 months.
Octomom may still be out there, I like to think. As a general rule among octopuses, brooding makes up a quarter of their lifespan. Check out some very remarkable footage here:
Images: MBARI news release (top, middle), 2014 Robison et al. (bottom)
UPDATE: Earlier version mistakenly said "53 weeks."
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