Amazingly, the suckers found on an octopus’s arms won’t stick to the octopus itself. If they did, octopuses would constantly tie themselves in knots.

Now, a team of researchers from the Hebrew University of Jerusalem has discovered how octopuses are able to do this: A chemical generated by octopus skin briefly stops their suckers from sucking.

“We were surprised that nobody before us had noticed this very robust and easy-to-detect phenomena,” explains Guy Levy. “We were entirely surprised by the brilliant and simple solution of the octopus to this potentially very complicated problem.”

Octopuses, unlike humans and other animals, don’t know where their arms are exactly. This notion raised the question: How, then, are octopuses able to avoid tying themselves up in knots?

To solve this mystery, the researchers watched the behavior of amputated octopus arms. They found that the arms never grabbed octopus skin, thought they would grab a skinned octopus arm.

“The results so far show, and for the first time, that the skin of the octopus prevents octopus arms from attaching to each other or to themselves in a reflexive manner,” the researchers note. “The drastic reduction in the response to the skin crude extract suggests that a specific chemical signal in the skin mediates the inhibition of sucker grabbing.”

Live octopuses, on the other hand, are able to override that automatic mechanism when it serves a particular purpose for them. They will, for example, sometimes grab an amputated arm, especially when that arm was not formerly their own.

Binyamin Hochner and his colleagues say that the animals’ self-avoidance behavior is yet another demonstration of octopus intelligence that might make its way into bioinspired robot design.

 “We hope and believe that this mechanism will find expression in such new classes of robots and their control systems,” Hochner posits.

The study’s findings are published in the journal Current Biology.