Octopuses, of course, have eight arms. But have you ever wondered if certain arms have certain jobs? Are some arms for grasping and others for swimming? Are there righty and lefty octopuses? Recent research shows the answer to all those questions is … no.
Cephalopods are the main attraction in Roger Hanlon’s lab, at the Marine Biological Laboratory in Woods Hole. Much of the research that happens there focuses on camouflage. But researchers are also studying and documenting how octopuses use their arms.
Hanlon and his team, along with researchers at Florida Atlantic University, just published a second paper in the journal Scientific Reports on arm flexibilities and complex behaviors of octopuses. The first paper focused on octopuses in the lab. This month, the journal published a follow-up paper focusing on octopuses in the wild.
Biologist Kendra Buresh manages Hanlon’s lab and was a co-author on both papers.
She explained, “We looked at the way that the arms can move together and the way that each arm can move. All the little tiny movements.”
The team cataloged all those movements and associated behaviors. For example, bending the tip of an arm to grasp an object.
Plus they documented four of what they call “arm deformations” – bending, making an arm shorter or longer, and torsion – twisting an arm in either direction.
Studying octopuses in various habitats, from a sandy seafloor to a complex coral reef, they were able to catalog octopus behaviors and how an animal’s arms help accomplish specific tasks.
Buresch said what an octopus can do with one arm, it can do with any arm.
“Basically, octopuses are the ultimate multitaskers,” she said. “They can use all eight of their arms. They can do every single one of those arm actions or arm behaviors with all eight of their arms. All four of those deformations can also be done in all eight arms and in all parts of their arm.”
MBL Senior Scientist Roger Hanlon said one of the reasons they’re studying octopuses is because their arms are “extremely flexible.”
“Maybe the most flexible arm in the animal kingdom, that’s been studied at least,” he said.
He said studying octopus arms could lead to some practical applications here on dry land, which is why the Navy has invested in this research.
“They're worried about crushed buildings, in particular, as an example, where there are people trapped under crushed buildings, whether it's an earthquake or terrorism or a wartime situation, and trying to deliver things and to find people,” said Hanlon.
A soft robotic arm, based on an octopus arm, might be able to get food, water or a cell phone down to someone trapped under rubble.
And Hanlon says, while octopuses do have good vision, they are really tactile animals.
“Most of their body is given over to those eight arms,” he said. “And every arm has more than 100 suckers, so that's already 800 to 1000 suckers. And every sucker has 5 to 10,000 neurons that taste and touch as well as grip things.”
Hanlon said there are potential medical applications as well for a sensitive and flexible robotic arm, for procedures such as tracheotomies, colonoscopies, and even brain and heart surgeries.
“The instruments that are used today, they’re metal and they're rough and they cause a lot of over-stimulation and a lot of even damage,” said Hanlon. “And the medical community is watching this sort of stuff really quite carefully.”
Hanlon said production lines and assembly plants might also benefit from soft robotic arms with more capability.
