little white point. But if the muscle’s contract, then the sack expands, and you can see the colors. And by expanding different combinations of these colors sacks to different degrees, the octopus can create all sorts of colors. Yes, Elizabeth? Student [email protected] And just with various combinations of those five colors, they can recreate any color in their environment? Professor Well, they can no doubt create a lot with just those five colors, but you are right, maybe they can’t mimic every color around them, so that’s where the second kind of cell comes 刘刘刘刘刘刘 刘刘刘刘刘 Learn and Share 刘 200
in. Just below the chromatophores is a layer of cells that reflect light from the environment, and these cells help the octopus create a precise match with the colors that surround them. The colors from the color sacks are supplemented with colors that are reflected from the environment, and that’s how they are able to mimic colors with such precision. So, that’s how octopus mimic colors. But they don’t just mimic the colors in their environment; they can also mimic the texture of objects in their environment. They have these little projections on their skin that allow them to resemble various textures. The projections are called papillae. If the octopus wants to have a rough texture, it raises the papillae. If it wants to have a smooth texture, it flattens out the papillae, so it can acquire a smooth texture to blend in with the sandy bottom of the sea. So the octopus has the ability to mimic both the color and the texture of its environment. And it’s truly amazing how well it can blend in with its surroundings. You can easily swim within a few feet of an octopus and never see it. Student I read that they often hide from predators by squirting out a cloud of ink, or something like that. Professor Yes. The octopus can release a cloud of ink if it feels threatened. But it doesn’t hide behind it, as is generally believed. Um, the ink cloud is ... it serves to distract a predator while the octopus makes its escape. Um, now there’s a third way that octopus can transform themselves to blend in with or mimic their environment, and that’s by changing their shape and size, well, at least their apparent size. [email protected] The muscular system of the octopus enables it to be very flexible to assume all sorts of shapes and postures. So it can contract into the shape of a little round stone, and sit 刘刘刘刘刘刘 刘刘刘刘刘 Learn and Share 刘 201
perfectly still on the seafloor. Or it can nestle up in the middle of a plant and take the shape of one of the leaves. Even Proteus would be impressed, I think.
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