Hey Steven,

Thanks for reading! I see what you are saying: wavelengths of visible light are only 'visible' to us because we have special receptors that respond to different wavelengths of light. What I find so interesting is how those different wavelengths of light are transmitted to our eyes in the first place: for most blue animals, this is by a trick of physics, where the physical structure can only reflect blue light (I've heard this be compared to a 'hall of mirrors'). As I biochemist, I find this astounding, as I tend to think of 'colour' being created by certain molecules absorbing certain wavelengths of light and reflecting others. So, in essence, it's the difference between a physical phenomenon and a chemical phenomenon.