Narrator: Now listen to part of a lecture in a Biology class.

Professor: Now many sea animals, in order to hide from predators, have over time develop different kinds of camouflage to help them blend in with their environment and avoid detection by predators.

Picture the surface of the sea floor.

It's as varied as the land we live on.

It's got peaks and valleys,

vegetation,

rocky areas,

and some sea animals have developed permanent colors or shapes to resemble these environmental features.

This camouflage helps disguise them from predators by enabling them to blend into a specific part of the sea.

For instance, take a kind of fish like the leafy seadragon.

Well, the name says it all.

It resembles a small, green dragon with leaflike protrusions sticking out like arms.

And because of its color and shape,

it blends in extremely well with green sea plants.

So when the leafy seadragon is swimming through these plants,

predators have trouble seeing it.

But when it enters other environments without these green plants,

its camouflage doesn't work anymore.

Now other sea animals are difficult to spot anywhere in the sea, because their type of camouflage enables them to change color.

Take the cuttlefish, a fish that is closely related to the squid and octopus.

Unlike leafy seadragons,

cuttlefish have not developed any particular shape to hide from predators.

But they have a lot more mobility because their camouflage allows them to blend into any environment,

because cuttlefish have shifting pigments that allow them to change color in a matter of seconds,

and so they can almost instantaneously match the color of their surroundings.

If they're swimming by green sea plants,

they'll turn green,

and if they're swimming over the brown sea floor,

they'll turn brown.