Octopuses live in the sea, in oceans all around the world. An octopus can change the color of its skin to blend in with its surroundings. It can change color faster than almost any other animal. The skin behind this trick holds a puzzle. First, let's look at how the skin works, and then at the puzzle.

The color change starts in the skin. An octopus's skin has special pigment cells called chromatophores, and these cells let it change color. Tiny muscles around each color sac squeeze it open or let it close, so the color shows more or less. This is how an octopus can blend in with its surroundings. It all works fast.

Skin can change in other ways too. An octopus can change the texture of its skin by raising bumps called papillae. The mimic octopus goes a step further, because it can copy the look and moves of several different animals. So an octopus can change how its skin feels, and one kind can copy how other animals look and move.

Some looks are meant to be seen. A blue-ringed octopus is a small octopus with bright blue rings. It flashes the rings as a warning. People should never touch one. An octopus can also squirt out a cloud of dark ink to help it escape. Rings and ink are two more ways an octopus can stay safe.

Now for the puzzle. You may have heard that octopuses change color because they see the colors around them and copy them. In fact, most octopuses are technically color-blind. Yet they can still match the colors around them. An octopus can change the color of its skin to blend in with its surroundings, even though it is technically color-blind.

Words to know

• chromatophores: color cells
• papillae: skin bumps
• texture: how skin feels
• mimic: copycat