July 31, 2014
Dedicated Octopus Mother Keeps Watch Over Her Eggs For Over Four Years
redOrbit Staff & Wire Reports - Your Universe Online
A team of researchers has discovered the most dedicated mother in the entire animal kingdom: a deep-sea octopus that protected and tended to her eggs for a period for 4 1/2 years until her offspring finally hatched.
In research published Wednesday in the open-access journal PLOS ONE, the study authors explain that an octopus typically has one single reproductive period during its lifetime, and while females tend to keep watch over their eggs until they hatch, the process usually takes no more than one to three months for most shallow-water octopus species.
On the other hand, deep water octopi are another story, as experts know little about their egg brooding practices. To learn more about these habits, Bruce Robison of the Monterey Bay Aquarium Research Institute (MBARI) and his colleagues used a remotely operated vehicle to monitor the Monterey Submarine Canyon off the coast of central California, where they discovered a deep-sea octopus on the seafloor at a depth of 4,600 feet in 2007.
“Over the next four and one-half years, the researchers dove at this same site 18 times,” MBARI explained in a statement. “Each time, they found the same octopus, which they could identify by her distinctive scars, in the same place.”
“As the years passed, her translucent eggs grew larger and the researchers could see young octopuses developing inside. Over the same period, the female gradually lost weight and her skin became loose and pale,” the Institute added. “The researchers never saw the female leave her eggs or eat anything. She did not even show interest in small crabs and shrimp that crawled or swam by, as long as they did not bother her eggs.”
The female octopus, Graneledone boreopacifica, spent the time clinging tight to a vertical rock face near a canyon floor, keeping watch over her roughly 160 translucent eggs, Reuters reporter Will Dunham said. The creature progressively lost weight and its skin grew pale over the course of the 53 month observation period (May 2007 to September 2011).
“It's extraordinary. It's amazing. We're still astonished ourselves by what we saw,” Robison told Dunham. “She was protecting her eggs from predators, and they are abundant. There are fish and crabs and all sorts of critters that would love to get in there and eat those eggs. So she was pushing them away when they approached her.”
“The first time that we… realized that she had gone up and laid a clutch of eggs, it was very exciting,” he added in an interview with BBC News. “Each time we went down it was more of a surprise, because we found her there again and again and again, past the point that anybody expected she'd persist. It got to be like a sports team we were rooting for. We wanted her to survive and to succeed.”
The creature’s amazing feat is a record gestation period amongst all animal species, noted Fred Barbash of The Washington Post, and the 53 month egg-brooding period shatters the previous octopus record of just 14 months. The primary question remaining, the study authors wrote, is to determine exactly how the mother was able to survive so long without food.
“The study team never witnessed the mother feeding, but they observed only about 18 hours of a 53-month brooding cycle. The scientists even offered her crab, but she didn’t take the bait,” said Amy West of National Geographic. “Robison surmised she might have occasionally eaten small crabs in defense of her eggs, a theory based on carcasses found close by. But one thing for sure is that Robison and his team found an invertebrate making the ultimate sacrifice to care for its young.”