Green and Brown Color Morphs
One of the most interesting features of these frogs is their ability to change color from brown to green. Previously, it was thought that there were two different fixed colors that an adult tree frog could be. Now it has been found that some of them are able to change between the two. They can also change from lighter to darker, shift from patterned markings to pure colors and vice versa, and even display combinations of colors, brown/green being the most frequent.
These color changing morphs are triggered not by color change in their environment, but a change in background brightness. This type of environmental change would be caused by seasonal fluctuation. A full change in the dorsal coloration of a color morph can take anywhere from weeks to months, but initial changes can occur in just a few hours. This has been shown to be a very useful cryptic survival feature for these frogs.
Skin color is produced via pigment cells called chromatophores. There are commonly three types of chromatophores found in amphibians: 1. Xanthophores - These contain yellow, orange, or red pigments and are found uppermost on the dermis; 2. Iridophores - These lie below the xanthophores and function by reflecting and scattering white light up through them; in the case of Pseudacris regilla and many other North American frogs, iridophores reflect blue light through the yellow pigment cells above to create a green frog; 3. Melanophores - These are the deepest pigment cells and are responsible for the presence of black and brown pigments.
A rare, recessive "blue morph" is known. There is one housed at the Humboldt State University Natural History Museum in Arcata, California. See link. It has been suggested that this mutation inhibits the xanthophores' ability to produce yellow pigments, thus the normally green frog (possibly of the non-color-changing type) appears blue.
Read more about this topic: Pacific Tree Frog
Famous quotes containing the words green, brown and/or color:
“Like the bee that now is blown,
Honey-heavy on my hand,
From his toppling tansy-throne
In the green tempestuous land—”
—Edmund Blunden (1896–1974)
“We gave ‘em wings to fly and they rained death on us. We gave ‘em a voice to be heard around the world and they preach hatred to poison the minds of nations. Even the medicine we gave them to ease their pain is turned into a vice to enslave half mankind for the profit of a few. Ah, Janet, dear, don’t you see? Every gift that science has given them has been twisted into a thing of hate and greed.”
—Karl Brown (1897–1990)
“The great God endows His children variously. To some he gives intellect—and they move the earth. To some he allots heart—and the beating pulse of humanity is theirs. But to some He gives only a soul, without intelligence—and these, who never grow up, but remain always His children, are God’s fools, kindly, elemental, simple, as if from His palette the Artist of all had taken one color instead of many.”
—Mary Roberts Rinehart (1876–1958)