Katie Rodriguez here. It’s Tuesday morning as I’m writing this, and I’ve just gotten off the phone with one of the researchers who recently spotted the elusive seven-armed octopus: senior scientist Steven Haddock of the Monterey Bay Aquarium Research Institute. I wanted to get an idea of what it’s like to be out at sea—waiting and watching as cameras are deployed to extreme depths—and to hear what it feels like when a discovery like this happens.
This octopus, whose scientific name is Haliphron atlanticus, has been seen four times in the last nearly four decades. Haddock, who was on an expedition with a group of researchers aboard the Rachel Carson vessel on Nov. 6, was in the control room with the pilot about lunch time, when he spotted something in the distance that looked intriguing.
“You never know what you're going to see,” he explains. “It’s kind of like going on a walk through the jungle, but every field of view has probably 1,000 little particles in it.”
The Rachel Carson, an MBARI research vessel designed for day trips, is equipped with a remotely operated vehicle about the size of a minivan. The ROV can be deployed to depths of 3,280 feet, collecting data and video footage; the tiny particles in the water column—a shower of organic detritus illuminated by the lights—are visible on the screens aboard the ship.
As they got closer to the animal, exclamations could be heard through the wall separating two rooms: one where Haddock and the pilot stood, and the other a viewing room with monitors where the rest of the crew watched.
Despite the octopus being as rare as it is, it was hardly a moment of confusion for Haddock—who recognized what it was quickly as they began approaching the octopus at around 2,296 feet.
“We got to the angle where it opened up its arms, and we could see inside that it was holding a jellyfish. That was super exciting to confirm that yet again, every observation we've had of this, it looks like it's holding a jellyfish,” he says.
The seven-armed octopus has been found up to 3,900 feet in depth, and actually has eight arms. But the males—what they saw on this expedition—keep a “modified” arm tucked away close to their beak (mouth) reserved for reproductive purposes.
The males are much smaller than the females, he explains, which can be 150 pounds and many meters long. This one, “[was] about the size of a football,” he says.
The previous sighting of the seven-arm octopus was in 2017, also eating a jellyfish.
Historically, researchers relied on nets to study deep-sea animals, a method that prevented them from seeing animals in their natural habitat and made it impossible to determine whether the contents found with the animal were true prey or simply bycatch brought up in the net.
“We're super fortunate to have this perspective on the deep sea,” he says. “The insights you get from seeing animals in their natural environment are incredible.”
You can learn more about this species, and others, here.