How do we know?
↻ One of the pages with a moving picture
Scientists shone light on pieces of octopus skin.
- An octopus’s skin is packed with tiny color sacs called chromatophores, in reds, yellows and browns.
- Nerves tell tiny muscles to stretch each sac open (the color shows) or let it shrink (the color hides).
- Other skin cells reflect light to add shine. Bumps called papillae change the skin’s texture.
- Scientists found that octopus skin can sense light by itself, even without the brain!
Scientists in Santa Barbara, California, shone light on small pieces of octopus skin, with no brain or eyes attached. The color sacs still opened up! Octopus skin can sense light by itself, even without the brain.
Many of the 300 kinds of octopus can change their color and texture to match their surroundings in seconds. The mimic octopus, discovered in Sulawesi, Indonesia, in 1998, can copy the look of other animals, like sea snakes!
Scientists believe octopuses are color-blind, so the skin is doing something clever.
Wow number
300 kinds of octopus live in the world’s oceans. Many can change their color and texture to match their surroundings in seconds!
Myth or fact?
Octopuses see lots of colors. Myth. Scientists believe they’re color-blind!
An octopus has three hearts. Fact. And its blood is blue!
Think about it
Why do you think an octopus might want to look like a rock?
Where in the world?
Sulawesi, Indonesia where the mimic octopus, discovered here in 1998, can copy the look of other animals, like sea snakes. Scientists in Santa Barbara, California, found that octopus skin can sense light — 1.43° S, 121.4456° E.
Where these facts come from
Every number on page 47, and who measured it
This page explains color sacs, shiny cells and papillae, and why scientists think octopuses are color-blind.
Cephalopod Camouflage: Cells and Organs of the Skin — Scitable, a science-learning site from the science journal Nature
nature.com/scitable/topicpage/cephalopod-camouflage-cells-and-organs-of-the-144048968
We checked it on 31 October 2026
This is the scientists' own report of the octopus skin and light test.
Eye-independent, light-activated chromatophore expansion (LACE) and expression of phototransduction genes in the skin of Octopus bimaculoides — The Journal of Experimental Biology, shared by the U.S. National Library of Medicine
pmc.ncbi.nlm.nih.gov/articles/PMC4448664
We checked it on 31 October 2026
This page tells us how many kinds of octopus there are, and that they have three hearts.
National Aquarium - Giant Pacific Octopus — The National Aquarium in Baltimore
aqua.org/explore/animals/giant-pacific-octopus
We checked it on 31 October 2026
This page tells us about the mimic octopus found in Sulawesi in 1998.
Mimic Octopus Facts — National Geographic, a science and exploring magazine
nationalgeographic.com/animals/invertebrates/facts/mimic-octopus
We checked it on 31 October 2026
This page tells us about the Santa Barbara study of octopus skin.
Seeing Without Eyes: A New Study Demonstrates that an Octopus’s Skin Possesses the Same Cellular Mechanism for Detecting Light as its Eyes Do — The University of California, Santa Barbara
eemb.ucsb.edu/news/all/2015/seeing-without-eyes-new-study-demonstrates-octopuss-skin-possesses-same-cellular
We checked it on 31 October 2026
This page, from the lab that did the study, tells us octopus skin senses light.
Octopus skin senses and responds to light — The University of California, Santa Barbara
labs.eemb.ucsb.edu/oakley/todd/news/476
We checked it on 31 October 2026
This page tells us that octopus blood is blue.
National Aquarium - Otherworldly Octopuses — The National Aquarium in Baltimore
aqua.org/stories/03-01-2018-otherworldly-octopus
We checked it on 31 October 2026
Has this changed?
How octopuses change color is not going to change, but we are still learning how their skin senses light.
New kinds of octopus are still being discovered, like the mimic octopus in 1998.
Words from this page
- chromatophore
- A tiny color sac in an octopus’s skin that can open or shrink.
- papillae
- Little bumps in an octopus’s skin that change its texture.
Try it!
Stretch a color dot like a color sac.
1. With a grown-up, draw a small dot with a marker on a balloon. 2. Blow the balloon up slowly, or ask the grown-up to. 3. Watch what happens to the dot. Throw away any popped balloon bits.
What happens: the dot stretches into a big patch of color. An octopus’s color sacs open up a bit like this!
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