What animal changes color to its environment?

A chameleon does, and also some varieties of octopi.

Marine Life: Side-swimming bottom feeding Flounder, Peacock Flounder, Mimic Octopus, Wonderpus Octopus
Mammals: Artic Fox, Artic Hare, Barren Ground Caribou, Ermine and Ptarmigan
Reptiles and Insects: Chameleon, Goldenrod Crab Spider, Peron's Tree Frog, Golden Tortoise Beetle



Read more: http://wiki.answers.com/Q/What_animals_can_change_colors_to_blend_in_with_it's_surroundings#ixzz1uKX5OEBQ

Chameleon can change its color according to its environment.

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One critter you forgot to mention.  Cotton mouth moccasin.  It is a poisonous snake that lives in Texas, Louisiana, Georgia, Florida, and Mississippi.  They change color according to seasons.  In winter, before they hibernate, they go blanched white or whatever color is under them.  In the spring, they change color again to green or gray, sometimes with a little speckled brown.

The reason we call them Cottonmouth is the color of the inside of their mouth when they want to bite you.  They can pack a wallop.

As the seasons change, the Arctic fox changes the color of its coat. In the spring and summer, it has a dark coat, to match the brown dirt in its environment. In the fall and winter, it turns white, to match the surrounding snow.

I have heard that Chameleons and octopi change their colors to blend in with it's surrondings.