Lesson 1
Living color pixels
Octopuses, squid, and cuttlefish have skin full of special cells called chromatophores (kroh-MAT-uh-fours). Each one is a tiny, stretchy sac of color: yellow, red, or brown.
- Around each color sac are tiny muscles, like the spokes of a bike wheel.
- When the muscles pull, the sac stretches wide and its color shows.
- When the muscles relax, the sac shrinks to a tiny dot you can barely see.
Nerve cells control the muscles, so an octopus can change color in less than a second!
Try this
Scroll up to the 3D skin and press the buttons. Watch the color sacs stretch and shrink!
Wow!
Thousands of color sacs work together like the tiny dots (pixels) on a TV screen to make patterns.
Lesson 2
Why change color?
- To hide. Matching the sand or rocks is called camouflage. It helps them hide from sharks and sneak up on crabs.
- To talk. Squid flash stripes and spots to send messages to other squid.
- To show feelings. An octopus may turn dark red when it's upset, or pale when it's scared.
Octopuses can even change the bumpiness of their skin, raising little bumps to look like rocks or seaweed!
Wow!
Scientists think most octopuses are colorblind, yet they still match their surroundings. Scientists are still figuring out how!
Lesson 3
More color tricks
Color sacs aren't the only trick. Under them are other cells:
- Shiny cells that reflect light and make sparkly blues and greens.
- White cells that bounce back whatever light hits them, to blend in.
Chameleons change color a different way! Their skin cells have tiny crystals inside. By spreading the crystals apart or squeezing them together, they change which colors of light bounce back. Chameleons mostly change color to talk to other chameleons and to warm up or cool down, not just to hide.