They Taste With Their Arms

They taste with their arms. Send this to whoever still thinks octopuses are just clever squid. An octopus reaching into a dark crack in a reef cannot see what is in there and cannot smell it either, because smell needs chemicals floating in the water. So it does something else. It tastes the rock.

Researchers at Harvard worked out how in twenty twenty. The suckers carry a kind of receptor found nowhere outside this family of animals, and what those receptors pick up are chemicals that will not dissolve and drift, the ones stuck to the surface of things. In other words, the octopus has to make contact. Touching and tasting are the same act.

And the decision does not always wait for the brain. Each arm carries its own dense network of nerve cells, roughly two thirds of all the animal's neurons sit out in the arms rather than in its head, and an arm can grab or reject something before the brain is fully involved. So when an octopus pulls back from a crack, it may have already decided, out at the end of one arm, that whatever is in there is not food.