Without joints and legs, an octopus arm can move in any direction. Then add that it contains eight, and you can imagine that it can be difficult to keep track of them all.
Now, Israeli researchers may have discovered evidence of how octopuses track its limbs, in a study published earlier in February in the Journal of Experimental Biology. The arms can interact with light, even if the octopus does not see the light in question.
It would investigate camouflage
Researchers at the Robin Academic Center made this discovery while studying an entirely different phenomenon, the ability of octopuses to change color. When they threw the octopus into the arms, they noticed that it was pulling them back, even though it was now asleep.
The researchers continued the experiments by allowing the octopus to search for food by sticking its arm into a hole in a place where it could not see what was inside. When researchers next shone on the octopus’s arm, it pulled its arm in 84 percent of cases, according to the New York Times.
They can feel the light through the arm. Nir Nesher, one of the researchers, tells the newspaper that they don’t need eyes for this.
Not just reactions
Exactly why octopuses possess this ability is not clear, but one theory is that they can remain hidden and not risk being bitten by hungry crabs or fish that can confuse an octopus arm with a worm when seen.
Researchers are also not entirely sure how this ability works. It doesn’t appear to be fully controlled, but it does require the squid’s brain to work. When researchers anesthetized the octopus, the ability to function was stopped. Octopus does not appear to depend directly on the skin. Because even if you got rid of a patch of skin, it responded to light when it fell directly on the core muscle.