Salamander's Eyes Experiment

I have 5 Tiger Salamanders at my home (as some of you already know) and I had been noticing a pigment constantly changing in their eyes. During the day when I feed them, there eyes are a beautiful gold. But at night their eye color changes to a deep black. I started to test if anything other than color changed. Everything that I could think of, reaction to light, reflexes, and even recognizably of objects or...me. They showed the same results even though they were in the dark rather than in the light, in fact, if anything they were performing better in pitch black darkness. I have come to the conclusion that the eye color is much like a stop light is to a car in that the darkness causes lack of pigment which allows them to activate their night vision surprisingly fast.

Let me know if you think differently.
Alex Cox