The reddish—orange coloration is a trait that is well adapted for a forested environment. The sunlight that filters through the forest canopy shines down on numerous levels of vegetation before reaching the forest floor. Vegetation absorbs red and orange light of the color spectrum. By the time sunlight reaches the forest floor, most of the red and orange light is filtered out, making it difficult to detect these colors in the forest environment. Light absorption enables the orangutan's coloration to virtually disappear, blending seamlessly into their forest environment.
Orangutan eyes are dark brown, an adaptation to help protect their eyes from sunlight. Darker eye colors have more pigmentation, than lighter colored eyes; absorbing sunlight before damaging UV light can penetrate to the back of the eyes.