Narrator: Listen to part of a talk in a biology class.

Professor: Okay, so on the topic of animal survival strategies, one type of strategy that's fascinated people for centuries is protective resemblance.

That's when animals resemble their environment in some way or another by taking on the color or shape, or both, of the physical objects that are behind or beneath them.

Today, we'll talk about two kinds, which kind of protective resemblance an animal has.

Well, it depends on whether the animal moves through different environments in the course of its life, or whether its environment is more or less permanent.

For example, animals like the horned frog.

Well, they've got the permanent kind of protective resemblance, which is fine.

Because, well, during the course of their lives, they don't visit other places.

So the horn frog is brown, just like the dead leaves on the forest's floor where it lives.

And it has got brown lines running down its body, just like the veins of the leaves.

The color and shape of its protective resemblance is fixed, like its environment.

So when the horn frog is on the forest floor, it's almost impossible for predators to see it.

Now, other animals, like euh... like the oily lizard, display a different sort of protective resemblance.

They actually change color, which is important for them because they travel through different environments as they live and grow.

So the protective resemblance they exhibit is adaptive, depending on the environment they're in.

The oily lizard has special moving pigments in its cells, which change to match the color of whatever environment it is currently occupying.

If the oily lizard is walking among the dead leaves of the forest's floor, it'll turn the same brown color as the leaves.

But if an oily lizard runs into some green shrubs, well, it'll turn green.