Masters of camouflage, cuttlefish are part of the cephalopod family – you know, like octopuses and squids. Find out how these amazing sea creatures use three colors, two layers of skin and papillae to make them the ultimate shapeshifters.
- Brains on.
MOLLY BLOOM: You're listening to Brains On, where we're serious about being curious. I'm your host Molly Bloom, and today, we're here to answer a question sent to us all the way from Lausanne, Switzerland.
SUBJECT 1: My name is Inuk, and I am seven years old, and my question is, how do cuttlefish change color?
MOLLY BLOOM: Cuttlefish are cephalopods. That's the same family of animals that includes octopuses. The eight arms of the cuttlefish are part of its head over its beak. Its body is shaped like a long oval and has an undulating fin around the edge that helps it swim. And just like an octopus, cuttlefish have three hearts.
There's a lot of cool things about cuttlefish, but it's their color-changing skin that's probably the coolest. Here to explain how they're able to change color is producer Sanden Totten. Hi, Sanden.
SANDEN TOTTEN: Hey, Molly. Can you find me?
MOLLY BLOOM: Are you under the table?
SANDEN TOTTEN: Yeah. Yeah, yeah, I was under the table. It turns out I'm not that great at hiding.
MOLLY BLOOM: No, you are no cuttlefish. They are the masters of camouflage. I saw this one video where the cuttlefish goes from sort of a purple polka dot and then changes into a brown and white almost zebra pattern. It was amazing.
SANDEN TOTTEN: Wow. That does sound pretty awesome. They're decked out with super special skin that helps them change color and texture in the blink of an eye, and quite honestly, I don't have that, so that's why I'm not as good. I learned about all this from Roger Hanlon. He's a senior scientist at the Marine Biological Laboratory at Woods Hole, Massachusetts, and he studies cephalopods, and he says they are the world's greatest shapeshifters.
ROGER HANLON: This is an animal group that has probably the most beautiful and complicated and changeable skin on Earth. And we all know the chameleon, and we love the chameleon. I think they're very cool, but they're dead boring by comparison.
MOLLY BLOOM: Wow. Those are some serious words. No offense to the chameleons listening. So how do cephalopods do it?
SANDEN TOTTEN: Well, let's start with the color. Cephalopods have millions of tiny colored organs in their skin called chromatophores, and they're kind of like tiny sacs filled with color pigments. Now, on the surface of the skin, they just kind of look like a very tiny, colorful freckle, and they come in three shades. You've got yellow ones, brown ones, and red ones.
Now, these are chromatophores, they're attached to muscles in the cephalopod skin, and these muscles can pull on these chromatophore organs and stretch them out or let go of them and shrink them. So imagine I was covered in these tiny, colorful freckle sacs, and I decided to stretch out all of the yellow ones. Suddenly, I'd look--
MOLLY BLOOM: Very, very yellow.
SANDEN TOTTEN: That's right. I would look very-- like maybe a Simpsons character. Cephalopods can do the same thing, and they can do it for the other colors, too. So they can expand just the red ones and look bright red, or they can do just the brown ones and look kind of brown. They can even mix the reds and yellows and browns and get a variety of shades when they do this.
MOLLY BLOOM: That is so cool. But they still need to get the blues and the greens to be really good at blending in with the ocean, right?
SANDEN TOTTEN: That's right. For that, cephalopods use a different layer of skin, one with reflectors in it.
MOLLY BLOOM: Oh, like tiny mirrors?
SANDEN TOTTEN: Yeah. Basically, they have these proteins in their skin that can reflect light. So cephalopods can manipulate those proteins in order to reflect back the blues and the greens and even purples coming from the light underwater. So you've got one layer of skin with reflectors that can give off blues, or greens, or purple colors, and the layer above that can change to look red, or yellow, or brown. When you combine those two layers, suddenly, you've got cephalopods that can mimic almost any color.
MOLLY BLOOM: That is amazing. So it's kind of like when you have a few paints, and you can mix them together to get all sorts of different colors.
SANDEN TOTTEN: That's right. Yeah. And that alone would be impressive enough for most people, but cephalopods, they don't stop there, Molly. They don't stop there. They get even more intense. Roger Hanlon told me these animals can also change the texture of their skin to help them blend in.
ROGER HANLON: So they can reproduce the three dimensionality of their skin when the background around them, like spiky little pieces of algae, and coral, and so forth. They can look spiky in their skin instead of smooth, or they can go smooth, as well.
SANDEN TOTTEN: He says they do this skin morphing trick, thanks to papillae in their skin. These are like little lumps. Hanlon calls them ultimate goosebumps. He says they can change shape the same way your tongue can. So you know, Molly, how you can kind of stick your tongue out and make it really pointy, something like this?
MOLLY BLOOM: Uh-huh.
SANDEN TOTTEN: And then, of course, you can flatten your tongue out in your mouth, kind of like this.
MOLLY BLOOM: Uh-huh.
SANDEN TOTTEN: Well, that's similar to how these papillae in the cephalopod skin work. They're kind of covered in lots of little super shifty tongues that can almost instantly get really pointy, or really flat, or really round, or really bumpy. And that way, they can approximate all sorts of bumpy patterns you'd see in the ocean, from rocks on the ground, to shells, to seaweed or maybe even coral reefs.
MOLLY BLOOM: Wow. So there is a lot going on in the skin of octopuses, and squid, and cuttlefish. How long does it take them to change shape and color?
SANDEN TOTTEN: Sometimes, they change shape and color in just 300 milliseconds. That's 1/3 of a second.
MOLLY BLOOM: Whoa.
SANDEN TOTTEN: That's pretty impressive. Roger Hanlon says he's been studying these animals for 40 years, and he still doesn't quite understand how they pull this off. It's still a mystery.
ROGER HANLON: So what's their secret? Is the octopus smarter than human? Well, in this case, it is. But it makes you think about the visual perception. You're going to look around you, as the octopus does, there's a tremendous amount of color and pattern information falling on your retina, but you don't have time to process all that because you require a brain the size of a Volkswagen. And to do it in 300 milliseconds, 1/3 of a second, there's got to be a shortcut, and it's that shortcut that has fascinated us.
SANDEN TOTTEN: There's a question for future scientists to tackle one day.
MOLLY BLOOM: Wow. That is amazing. Thank you for sharing all this with us, Sanden.
SANDEN TOTTEN: No problem.
MOLLY BLOOM: See you later.
SANDEN TOTTEN: Later, Molly.
(SINGING) Ba ba ba ba ba ba ba ba ba ba ba brains on.
MOLLY BLOOM: Do you have any questions you'd like to hear answered on Brains On? Send them to us at brainson at M, as in Minnesota, pr.org. We hear from kids all over the world, and they send us amazing questions, fantastic mystery sounds, and rhymes. Like Louie Marie from Tahiti. He keeps a science journal, where he draws insects he finds in the yard or writes about the solar system.
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And before we go, we want to make sure your ears are on. Testing, testing, can you hear me? It's time for the mystery sound.
SUBJECT 2: Mystery sound.
MOLLY BLOOM: Here it is.
What do you think? Let's hear it one more time.
Any guesses? They are really fun to play with but not fun to step on. Here's the answer.
SUBJECT 3: I'm Logan from Riverview, and I'm seven years old. That was the sound of me searching for LEGOs. I like that sound because I like building with LEGOs.
MOLLY BLOOM: Thanks, Logan.
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That's it for this episode of Brains On. We'll be back in a couple of weeks with more answers to your questions. Thanks for listening.
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