Hands-on Science and

Engineering at Pasadena

Public Library

Oct. 22, 2014

Many animals are born with skin that’s the same color as

their environment—an adaptation that protects them

from predators. But how is it that a frog, chameleon or

octopus can literally change the color of its skin, in

SECONDS?

Chromatophores, or

pigment sacs in their skin,

that expand and contract!

These animals have

pigment sacs of many

different colors, usually

brown and yellow but

sometimes green, red or

other colors. They sense

the color of their

environment and

instinctively choose which

pigment sacs to expand and

which ones to contract.

http://phys.org/news/2013-05-

chameleons-creatures-colour.html

Build octopus chromatophores!

“The outer layers of

octopus skin are

covered with

chromatophores, which

are tiny cells containing

brown, red, and yellow

pigments. Each

chromatophore is

controlled by a muscle

and a nerve. The

octopus’s brain sends a

signal along the nerve

to tell the muscle to

contract, and when it

does so, the

chromatophore changes

color.”p. 16, Octopuses by Melissa Gish, published by

Creative Education

“In addition to

color, the octopus

can also change its

skin texture. Tiny

knobs on the skin,

called papillae,

can lie flat or rise

up into bumps or

ridges, instantly

giving the octopus

a smooth or rough

appearance.”

p. 16-18, Octopuses by Melissa Gish, published by

Creative Education

Scientists don’t know exactly how octopuses are so adept at matching the color of their environment without being able to distinguish those colors with their eyes. They believe it’s due to a kind of cell in the outer layer of the octopus’s skin that reflects the environment and responds to light, and the nerves connected to the chromatophores respond by matching the color wavelength they “see.”

“Woods Hole Marine Biological Laboratory and University of Washington researchers found that the skin of the cuttlefish Sepia officinalis, a color-changing cousin of octopuses, contains gene sequences usually expressed only in the light-sensing retina of the eye. In other words, cephalopods—octopuses, cuttlefish, and squid—may be able to see with their skin.”

From “Inside the Mind of the Octopus” by Sy Montgomery, published in Orion Magazine in November/December 2011.

http://www.orionmagazine.org/index.php/articles/article/6474/

Challenges:

*Try making all the balloons of the same color expand with one pull, the way an octopus would send a signal to all the brown chromatophores to expand!

*Try making papillae or bumps that can rise and retract!