Unlike humans, the walnut-sized brain of octopuses is not always aware of the mollusc’s arm locations. Yet, thanks to a chemical produced by octopus skin, the arms prevent their suckers from sucking when in contact with one another.
“We were surprised that nobody before us had noticed this very robust and easy-to-detect phenomenon,” says Dr. Guy Levy, who carried out the research with co-first author Dr. Nir Nesher in the Department of Neurobiology at the Hebrew University’s Alexander Silberman Institute of Life Sciences. “We were entirely surprised by the brilliant and simple solution of the octopus to this potentially very complicated problem.”
Instead of calculating when and where its arms will move, the research shows that the octopuses avoid contact among their limbs from go.
They placed amputated octopus limbs in water and noticed that the octopuses never grabbed octopus skin, though 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 write. “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.”
Now, the scientists say the self-avoidance strategy might even find its way into bio-inspired robot design.
“Soft robots have advantages [in] that they can reshape their body,” Nesher says. “This is especially advantageous in unfamiliar environments with many obstacles that can be bypassed only by flexible manipulators, such as the internal human body environment.”
The researchers are sharing their findings with European Commission project STIFF-FLOP, which aims to develop a flexible surgical manipulator in the shape of an octopus arm.
“We hope and believe that this mechanism will find expression in such new classes of robots and their control systems,” says Prof. Binyamin Hochner, Principal Investigator in the Hebrew University’s Octopus Research Group.