What Makes Animals Have Different Colors? by Elaine A. Powers, Author

In a previous post, I mentioned the different color-morphs of green iguanas. You might be interested to know what causes animals to come in these different colors.

The colors in reptiles and most other animals come from fascinating cells called chromatophores. Chromatophores are cells that contain pigments, one color per cell. Melanophores contain black pigment, erythrophores have red, xanthophores are yellow, and leucophores are white. Iridiophores are the cells containing the reflective pieces that produce iridescence (as seen in Bahamian Boas, A Tabby Tale above). The presence of and combination of these different cells determine the color patterns of the animal.

Chromatophores are located in the basal or lower layers of the epidermis. When a reptile sheds its upper epidermal layer, you’ll notice there are no colors in the old skin. That’s because the pigment cells are deeper.

The pigment granules inside the cells can be moved around. If you’re a cold-blooded (ectotherm) reptile and need to warm up, you would expand the black pigment in your melanophores to absorb more of the sun’s rays. When you were nice and warm, you would cluster the pigment back into the cell.

Chameleons are famous for their ability to alter their color patterns. They are able to do this by expanding and contracting the pigment granules within the various colored cells.

Hormones affect the expression of the colors. Iguanas become much brighter in color during mating season, when they need to attract a mate.

It’s a shame we humans only have the black pigment (melanin) chromatophores. Think of the fun we would have if we could change colors like a chameleon.

Interested in learning more about iguanas? Please see Lyric Power Publishing’s educational, supplemental workbook, My Unit Study on Iguanas.