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# Polka Dots: How Do Chameleons Change Colors?

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Source:
Author: Janice VanCleave

### Problem

How do chameleons change colors?

### Materials

• magazine with colored pictures
• desk lamp
• magnifying lens

### Procedure

1. Place the magazine under the light of a desk lamp.
2. Hold your face about 6 inches (15 cm) above one of the colored pictures in the magazine.
3. Close one eye. Use your open eye to look through the magnifying lens at the colored picture.
4. Move the lens back and forth between your eye and the magazine picture until a clear image forms.
5. Carefully study areas of different colors.

### Results

You will see that every color is a combination of colored dots.

### Why?

The color of a chameleon's skin, like the colors in the picture, is actually a combination of colors. The skin of this lizard has layers of cells called chromatophores. Each cell contains color matter called pigment and comes in different colors, including red, brown, yellow, and white. Special chromatophores called melanophores contain a dark pigment. These special cells have a center section with branches sticking out in all directions. Temperature, light, and chemicals in the animal's body cause the pigment to expand and, thus, move out into the branches of the cell or to contract and concentrate in the center of the cell.

When the branches of the melanophores are empty, the color pigments in the other cells show through. When the branches are filled with the dark pigment, they hide some of the colors in the other cells. The combinations of the pigments result in skin colors including red, yellow, green, brown, and gray.

### Let's Explore

What color combinations make up the individual colors of red, yellow, green, brown, and gray? Repeat the experiment, recording the color combinations observed for the specific colors. Science Fair Hint: Use colored construction paper to prepare enlarged models of the color combinations viewed through the magnifying lens. Display the models.

### Show Time!

1. How do the different -colored dots look like one color? The brain receives the light from the separate color dots and blends them together. Demonstrate the blending of light from separate objects by using different colors of cellophane. Lay the colored pieces so that their edges overlap. Use the cellophane as part of a project display.
2. How does light affect the color of the chameleon's skin? In intense sunlight, the skin becomes darker, as does the skin of humans. In the absence of light, the skin becomes lighter. Since different colors of skin contain different amounts of pigment, ask several people with varying skin colors to wear a plastic bandage on one finger. Remove the bandage after several days and observe the color of the skin outside and inside the area covered by the bandage. Color photographs can be displayed.
3. Are the colors in a bird's feathers due to color pigment? Actually, the bright blue color of some bird's feathers results from the scattering of light waves. Tiny air bubbles in the feathers scatter the blue light coming from the sun, which results in the feathers appearing to be blue. You can demonstrate the scattering of blue light by filling a glass with water and adding one drop of milk to the water. In a darkened room, use a flashlight to direct a light beam through the center of the water. The water appears to be a grayish blue. If more blue waves were reflected, a brighter blue would be seen.

### Check It Out!

An animal can be colored or can have patterns of colors that allow it to blend well with its background. This makes it difficult to see. Find out more about the protective coloration of creatures.