It occurred to me recently that no animals have blue or green fur. Why not? There are animals with fur in various shades of red, orange, yellow, tan, brown, gray, white, black. I suppose that animal biochemistry is capable of creating blue or green fur. There seems to be no limit to the colors possible for birds, butterflies, and flowers. Is there no evolutionary advantage to these colors? Green seems like wonderful camouflage for an animal who lives in a jungle, forest, or a green meadow. Is there anybody here with a knowledge of biochemistry who might be able to tell me if blue or green fur is possible? Is there any evolutionary reason why these colors do not occur?