Hey, this is Flor Lichtenen, and you are listening to Science Friday.

Today in the show, the mysterious ways that octopuses use their arms to sense the world around them.

Could it be that certain arms are specialized for certain functions? Maybe it's not that they're all tongues, as you said. Maybe they're

all doing different things. Put on your party hat and wetsuit because it's cephalopod week,

our annual celebration of all things, octopuses, squid, and cuttlefish. And to kick things off, we are

bringing you an ode to the octopus arm, which I learned is not called a tentacle. Believe it,

it's an arm. You may have heard that octopuses can use their arms to taste their surroundings,

but how exactly does that work? New research provides

some clues. Here to tell us more is Dr. Nicholas Bolono, professor of molecular and cellular

biology at Harvard University in Cambridge, Massachusetts. Nick, welcome back to Science Friday.

Thank you. Okay, tell me what you found. So years ago now, we found that octopuses actually have receptors in the suckers of their arms,

which are proteins that bind molecules from the environment to inform an animal about its surroundings,

similar to how we taste or smell.

And so we came up with this story, basically, which was that if the octopuses is exploring

its environment using this chemotactile sense or this taste-by-touch sense, then it would make

a lot of sense that the animal would be detecting

these relatively insoluble molecules that would adhere to surfaces.

And that would be different than, let's say, a soluble molecule that would diffuse through the

water that maybe, you know, a fish uses to track down prey at a distance.

But the octopus is exploring by touch. So that's kind of

where we started with this whole exploration of the arms. And that was a surprising discovery. And that's

sort of the story that we had. But we actually didn't know what they sense in their environment.

...