Octopuses are often considered an ‘alien’ type of intelligence, because they’re so different from animals we usually consider ‘smart’. They evolved differently than pretty much any other organism on Earth. But with their ability to solve cognitive puzzles and their surprisingly creative behavior, they’re definitely smart creatures.

Recent research shows octopuses may be even more alien-like than we thought. Apparently, much of the nervous system involved in decision-making is actually not concentrated in the brain but distributed throughout the body. Essentially, their arms can make their own decisions.

Alien intelligence

Cephalopods, the group that includes octopuses and squids, evolved some 530 million years ago. It’s a group of invertebrates, which means they lack a spine — already, a key difference from creatures like humans or dolphins. But it gets even weirder.

Rather than having a centralized nervous system, the octopus’ nervous system is spread throughout its body. Two-thirds of its neurons are not inside its brain. Researchers aren’t even sure how this system can work, but it does.

“One of the big picture questions we have is just how a distributed nervous system would work, especially when it’s trying to do something complicated, like move through fluid and find food on a complex ocean floor,” said neuroscientist David Gire of the University of Washington.

“There are a lot of open questions about how these nodes in the nervous system are connected to each other.”

But it gets even more interesting. Many of these neurons can communicate with each other without going through the brain. Essentially, the nervous system inside the octopus’ arms can bypass the brain and communicate with each other.

This means the brain may not even be aware of what all the arms are doing while the arms are sort of doing their own business.

“The octopus’ arms have a neural ring that bypasses the brain, and so the arms can send information to each other without the brain being aware of it,” said behavioural neuroscientist Dominic Sivitilli of the University of Washington.

“So while the brain isn’t quite sure where the arms are in space, the arms know where each other are and this allows the arms to coordinate during actions like crawling locomotion.”

In order to figure this out, the researchers tracked the behavior and brains of octopuses as they foraged and explored. Sometimes, the arms moved in sync, suggesting organized decision-making. Other times, each arm did its own activity. When they looked at the brain activity of octopuses, researchers found the most curious thing. When the octopus arms and suckers were gathering information seemingly individually, the brain didn’t do a thing.

In other words, the octopus brain is not even aware of what the arm is doing, which is hard to even fathom.

“You’re seeing a lot of little decisions being made by these distributed ganglia, just by watching the arm move, so one of the first things we’re doing is trying to break down what that movement actually looks like, from a computational perspective,” Gire said.

“What we’re looking at, more than what’s been looked at in the past, is how sensory information is being integrated in this network while the animal is making complicated decisions.”

This stunning ability isn’t even all that surprising for octopus researchers, as it’s been suggested several times in the past. But it poses some key questions about what intelligence really means, and whether intelligence very different from ours can exist.

Octopuses are, from everything we know about them, exactly that — a different type of intelligence.

“It’s an alternative model for intelligence,” Sivitilli said. “It gives us an understanding as to the diversity of cognition in the world, and perhaps the Universe.”

The word was presented at the Astrobiology Science Conference.