Why octopus never gets entangled

Ever wondered why the hundreds of suckers lining an octopus' arms do not grab onto the octopus itself?

That is because a chemical produced by octopus skin temporarily prevents their suckers from sucking, discovered researchers at Hebrew University of Jerusalem.

"We were surprised that nobody before us had noticed this very robust and easy-to-detect phenomenon," said lead researcher Guy Levy.

"We were entirely surprised by the brilliant and simple solution of the octopus to this potentially very complicated problem," he added.

In the lab, the researchers observed that octopus arms remain active for an hour after amputation.

Those observations showed that the arms never grabbed octopus skin, though they would grab a skinned octopus arm.

The octopus arms did not grab Petri dishes covered with octopus skin, either, and they attached to dishes covered with octopus skin extract with much less force than they otherwise would.

"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 wrote.

"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," the research, published in the journal Current Biology, suggested.