An octopus’s arms are covered with suckers which will stick to just about anything, with one important exception.
They generally won’t grab onto the octopus itself. Otherwise, the flexible animals would quickly find themselves tangled up.
Researchers from the Hebrew University of Jerusalem have discovered a chemical produced by the octopus skin temporarily prevents their suckers from sucking themselves.
Binyamin Hochner and his colleagues had been working with octopuses for many years focusing on their flexible arms and body motor control.
There is a very good reason that octopuses don’t know where their arms are exactly, in the same way that people or other animals do.
“Our motor control system is based on a rather fixed representation of the motor and sensory systems in the brain in a formant of maps that have body part coordinates,” Hochner says.
That works for us because our rigid skeletons limit the number of possibilities.
“It is hard to envisage similar mechanisms to function in the octopus brain because its very long and flexible arms have an infinite number of degrees of freedom,” Hochner says.
“Therefore, using such maps would have been tremendously difficult for the octopus, and maybe even impossible.”
Experiments have supported the theory that octopuses lack accurate knowledge about the position of their arms. And that raised the question: How do octopuses avoid tying themselves up in knots?
”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.
This octopus self-avoidance strategy might find its way into bio-inspired robot design.
The researchers are sharing the findings with European Commission project STIFF-FLOP which is aimed at developing a flexible surgical manipulator in the shape of an octopus arm.
The results of the study are reported in the Cell Press publication Current Biology.
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