Squid, Octopus, Cuttlefish: Masters Of Camouflage

Cephalopods have several tricks for blending in with their undersea surroundings: they can change color, pattern and even the shape of their skin. Roger Hanlon, a biologist at the Marine Biological Laboratory in Woods Hole, describes how you find and film sea creatures in hiding.

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IRA FLATOW, host: Time now for our Video Pick of the Week. Flora Lichtman, our multimedia editor is here, and I know what you have in store because I've looked at this video and it's unbelievable.

FLORA LICHTMAN: I know, Ira. This is a video that I don't actually think we could oversell if we tried.

(SOUNDBITE OF LAUGHTER)

FLATOW: I know.

LICHTMAN: This is - well, like, this is a run, don't walk to your laptop or a desktop computer video because this really - your mind is going to be blown. It's going to be great.

FLATOW: OK. Now tell me what it is now that we're going to be...

(SOUNDBITE OF LAUGHTER)

LICHTMAN: Now that you're primed, it's about cephalopods, which are squid, octopus and cuttlefish, and it's about how they camouflage and go in and out of hiding. And actually, we have the scientist who collected most of the footage in this video here with us. Roger Hanlon is a senior scientist at the Marine Biological Laboratory in Woods Hole. Hi, Roger. Welcome to SCIENCE FRIDAY.

Dr. ROGER HANLON: Yes, hello. Thanks. It's great to be here.

LICHTMAN: So the video you gave me, one of them, you call it your wow video, and so maybe you can tell us why you call it your wow video. Set the scene.

HANLON: Well, the scene is this: diving along a shallow coral reef in the Caribbean and there's a rock sitting out in a sand plain, all by itself, and it's just looks like a plain, boring rock. And as the video comes a little bit closer to the rock, suddenly, one-third of it turns into a bright white octopus that has been beautifully camouflaged, and suddenly goes out of the camouflage because the cameramen are so close and then it inks in the face and swims off. So you - it really was - I think I yelled wow at the moment of...

FLATOW: Underwater?

(SOUNDBITE OF LAUGHTER)

HANLON: Yes. I wasted a little air on that one.

LICHTMAN: And it happens really fast, right?

HANLON: Yes, they can change their pattern and coloration in about one-half of one second.

LICHTMAN: Wow.

HANLON: So this is the fastest color change and the most diverse color change of any animal group we know of.

FLATOW: Well, this video is up on our website at sciencefriday.com. And when I saw it, I mean, it's - the - not only does the color changed, but the skin shape matches and the texture matches whatever it's near, right?

HANLON: That's right. It's quite extraordinary. They not only change the pattern and the color and the contrast to achieve camouflage, but the three-dimensionality of the skin, the physical texture of the skin changes to match the backgrounds as well. And that also is under visual control and it's also very fast.

LICHTMAN: I mean, how do they do that? That's what I want to know. You look at the video and, you know, I've showed it to a bunch of people and they're, like, this has to be fake because it just looks so unbelievable. So what's involved?

HANLON: Yes, at least half the people who look at this decide it's fake, so we do a lot of explaining in reverse. And by following this in reverse, slow motion, you see some of the dynamics.

Now, the simpler answer is that they do it visually. In other words, they have very keen eyes. The eyes are assessing in the information immediately around then. And then, with that visual information, they implement all these body patterns, that means controlling over 30 million chromatophore organs. These are pigmented organs in the skin, all directly innovated from the brain. And to get those muscles to create the three dimensionality, we call these papillae, also requires visual input and direct neural control. So it's all visual input and nervous system control of the skin. So we glibly call this electric skin sometimes.

LICHTMAN: So they don't have to touch anything. I mean, I think that's kind of an amazing thing, right? To make this three dimensional skin, they don't have to actually feel it. They can just do it visually.

HANLON: That's right. We've done controlled experiments on cuttlefish, which are related to octopus, and showed that just by visually looking at the fine texture of the background, they can reproduce that in the skin. There's some possibility that the octopus has used some of the touch receptors. We haven't done real experiments on octopus, but it seems as though most of it is driven by visual information only.

LICHTMAN: What about the colors? I think you told me that they are color-blind. So how are they are matching the colors?

HANLON: Right. This is one of the really vexing questions, how do you achieve color-blind camouflage if you're a soft-bodied, yummy animal in the ocean that everyone is trying to eat? The simple answer is that we're not really sure. We have done experiments and others have done experiments to show that these animals don't have the equipment and the eye to perceive color and behaviorally they don't react to color. However, they're doing a spectacular color match to every background they go on.

And I should add that this octopus can move anywhere on a coral reef, which is the most visually diverse habitat on the planet. And they can achieve camouflage, including color matching. So I'm afraid we're a little ignorant in the science world to give you a good explanation of really how they do that color matching.

LICHTMAN: Yeah, people think about chameleons, I think, as sort of the quintessential camouflage animal. How do they rank up? If you were to put them in a competition for camouflage, who would win?

HANLON: Well, the cephalopods win hand down. I think the chameleons are very...

(SOUNDBITE OF LAUGHTER)

FLATOW: Absolutely. When you see...

HANLON: (Unintelligible) the animals, frankly, they are a little boring compared to the cephalopods which can do it much faster and with much greater diversity.

LICHTMAN: Wow. That's...

FLATOW: Do they evolve this over time? Do we - seal or - you know, are there any relatives out there than can't do as well but, you know...

HANLON: It turns out that all of the, sort of, extant or commonly seen cephalopods on the planet today can do all this beautiful color change. But remember, this is a mollusk. It's related to an oyster or a clam, and those animals certainly are different. They have shells on the outside. These animals, the cephalopods, have evolved very differently to get rid of all the external shell and to survive on their wits, so to speak. And that is they have a good sensory systems, great coloration. And in one way, they manifest all - let's say, all of their behaviors manifest through these patterns in the skin, whether it's signaling or communication or the opposite which is camouflage.

LICHTMAN: Can they - is it pretty predictable what pattern they're going to flash? If you put different animals in the same background, will you get the same pattern?

HANLON: You do generally get the same pattern. Of course, there's variations like in every species. But in general, the camouflage has to work every time or, you know, they're not - no longer in the gene pool. The predation on these animals is very extreme. And so, yes, you put 10 octopuses on 10 of the same background and you would generally get the same pattern response because the camouflage has to work in the context of that little microhabitat against which they're being viewed by these very capable predators.

FLATOW: This is SCIENCE FRIDAY from NPR. I'm Ira Flatow here with Flora Lichtman, talking with Roger Hanlon about the incredible video we have up on our website at sciencefriday.com of an octopus or a lot of octopi. He says octopuses, not octopi. A change...

LICHTMAN: Is it octopuses? I just want to see...

FLATOW: ...changing to match their background, any shape, size, color, texture, and it's almost as if - if you look at the close up of the skin that we have on the video - it's almost as if you're watching a high-definition video screen.

HANLON: That's really quite a good analogy, Ira, because they do have these pigmented organs in the skin. And in this simplistic way, they turn some off and others aren't turned on to create the patterning. And they have three color classes, yellow, red and brown, and that creates most of the patterning. But they also - underneath the pigments, they have reflectors, iridophores. They have an iridescent color, and they produce complementary colors so that the full artist palette of color is available through the skin here. And so this is very much like a high-resolution computer display.

FLATOW: Do they ever get - did you ever try to trick them, maybe a moray pattern or something that's impossible or something that they can't do?

HANLON: Yes, we do give them impossible backgrounds. This is called the psychophysics approach where you try to cut down the number of variables so we can understand what they respond to. So we've given them black and white checkerboards. And believe me, I haven't seen any of those underwater yet. And so these animals haven't evolved into something as ridiculous as that but, you know, this...

FLATOW: Give them a little bit of time.

(SOUNDBITE OF LAUGHTER)

HANLON: Yeah, we'll give them a little time. But it does tell us which part of the checkerboard they do pay attention to. And we do those controlled experiments so that we can understand what turns on the right camouflage patterns, and that's the nature of our laboratory experimentation here at the Marine Biological Lab.

LICHTMAN: Dr. Hanlon, what do they do when they're sleeping?

HANLON: Well, we're not so sure they sleep. That's a controversial question. But I will tell you this, they stay camouflaged all day and all night. And we also know that the camouflage is beautifully tuned to the background even under what we would call full darkness or starlight, and that they can even change under that level of light. So unlike humans, they can see in the dark and that means they have some pretty good visual predators in the dark too.

FLATOW: I would think that DARPA would be very interested in these guys, you know, the military...

HANLON: There are a lot of people interested in these guys, partly for the bizarre factor. But if you think of advertising and material scientists and people who would do anything with color and pattern, being able to change it like the skin of the animal, is of great interest. And so we do a lot of work with the material science and engineering communities to try and produce changeable materials based on the skin of these animals.

FLATOW: Is there - I mean, how many pixels - I mean, they are controlling. As I say, it looks like a high-definition TV screen. Are they actually controlling it? What - they all flash at the same time as if it is a screen. Is it like a pixilated, sort of, grid work, or how does it connect together?

HANLON: Yes, it is a pigmented pixilated, sort of, network. And the density is about 300 of those chromatophores per square millimeter, or you could call that dots per inch on a computer screen, and that is high resolution. And so - and there are a lot of species that have not so high resolution skin, depending on which complicated environment that species occurs in. But the one you're seeing on this video is one of the best camouflage artists of all the cephalopods. And, yes, it is a high-resolution screen, and it's a pretty diverse arrangement of skin patterns that it can produce.

LICHTMAN: And that is really - it's worth looking at this. I'd never seen anything like that. Dr. Hanlon, thanks for joining us on the show today.

HANLON: Well, no, it's my pleasure.

LICHTMAN: Roger Hanlon is a senior scientist at the Marine Biological Lab in Woods Hole.

FLATOW: Thank you, Flora. If you want to see this video - and I'll tell you, if you want to see one video, this is the one to see this week, up on our website at sciencefriday.com. It's our Video Pick of the Week. It's an octopus that you will not be able to find in all kinds of places. Where is the octopus? Thank you, Flora.

LICHTMAN: Thanks, Ira.

FLATOW: Great video. That's about all the time we have for today.

And if you missed any part of our program, go and download them on iTunes or subscribe to our podcast, our audio and video, and you can even download this video of the octopus a podcast. We have them up there on iTunes and you can subscribe to our video podcast as well and share this one with your folks this evening. I'm Ira Flatow in New York.

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