An octopus’s arm is covered with hundreds of suckers that give it a strong tendency to attach to everything it encounters but the octopus’s arms. A team of researchers has shown that chemical signals from the skin of octopus protect its arms from attaching to each other or onto themselves, without which the octopus might end up entangled.
The team studied the behaviour of severed octopus arms — which remain active and move for at least an hour following separation — because arms have their own network of neurons that to some extent can work independent of the central control of brain.
Suckers on severed arms — like the ones on intact arms — attached to any surface but avoided the skin. They did attach to another arm but only at points where the skin was damaged or missing, suggesting that the skin, wherever present, might play a role in inhibiting the attachment.