If you thought nine months was long, consider watching over your eggs for four and half years—only to die at the end.
A deep-sea octopus, Graneledone boreopacifica, has set a new record for brooding stamina—53 months, the longest developmental period known for any organism, according to a study published July 30 in the journal PLOS ONE.
This beats the 14 months on record for an octopus, and really any animal, including the estimated 48 months of gestation in the alpine salamander. Octopuses that live in shallow waters, which are better studied, care for their eggs for only a few months.
What’s more, life spans for nearly all cephalopods—a group containing squid, nautilus, octopus, and cuttlefish—are a short one to two years, which G. boreopacifica outlives by its brooding time alone. Thus, this species also snatches the title of longest lived.
“She’s Still There!”
The discovery comes down to observational luck. In 2007, study leader Bruce Robison was using a robotic vehicle at about 4,500 feet (1,400 meters) deep off the coast of central California. He captured video of a purple octopus crawling toward a rock wall favored by brooding octopuses. (See “Journey of Octopus Discovery Reveals Them to Be Playful, Curious, Smart.”)
A month later, Robison, a deep-sea biologist at the Monterey Bay Aquarium Research Institute, and his team noticed the same female, easily identifiable by distinctive scarring, firmly attached to the rock and protectively curled over her fragile, transparent eggs.
The team returned 18 times over the next 53 months to record the incredibly slow growth of the babies in 37-degree-Fahrenheit (3-degrees-Celsius) water, as well as the gradual wasting away of their motionless mother.
After two years, the consensus was that she wouldn’t last much longer—but she kept proving them wrong. Robison would frequently exclaim, “Holy sh*t, she’s still there!”
Finally, in October 2011, she was gone, and more than 150 eggs lay broken open.
“This is the only opportunity that anybody has ever had to trace a brooding period” of a deep-sea octopus, said Robison. “We had a start date and we couldn’t let go until we got to the end.”
Go, Baby, Go!
Scientists know little about reproduction in the deep sea, but they speculate the octopus’ long development is due to slow metabolism brought on by colder temperatures.
There’s another result to this lengthy incubation: Baby G. boreopacifica are the most highly developed octopus hatchlings known to date, said Janet Voight, associate curator at the Field Museum in Chicago, who wasn’t involved in the research.
Unlike some shallow-water octopuses that have a planktonic stage, G. boreopacifica pop out as small but complete versions of their parents, giving them a greater survival boost in the dark and lonely deep sea.
The mother’s investment in her eggs also means she releases larger, but fewer, eggs—a few hundred versus thousands. (See “Social Octopus Species Shatters Beliefs About Ocean Dwellers.”)
However, this study involved just one animal, which raises the question of whether the egg-rearing stint is an anomaly.
Voight said the lengthy brooding behavior is probably typical for the species. “Of course, more data are better, but it’s the deep sea”—a challenging place to conduct research.
As with many deep-sea discoveries, another mystery has surfaced: Did this mother octopus not eat for nearly five years? After all, “as a rule, most octopuses never leave their eggs,” said Robison. Voight added that octopuses brooding in warm water don’t eat. (Related: “‘Bizarre’ Octopuses Carry Coconuts as Instant Shelters.”)
No one knows. 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. 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.
“We tend to think of parental care only in higher life-forms, but here’s a parent who is going all out to ensure the survival of her offspring.”
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