User blog comment:Lord Loss/Monster Hunter Theory... Blog/@comment-1758220-20130422062858

Interesting info about Green Nargacuga's scales. The game states that their colour "...shifts in response to light, blending into the scenery."

I guess this means that G. Narga has photosensitive scales that can change colour like a chameleon or octopus, albeit with a lesser range of colours, to allow it to blend in with the environment as effectively as possible. Quite a cool adaptation if you ask me.