Extreme color change!

[CrotalusR#1]

This is an adult male Arizona black rattlesnake (crotalus Cerberus)

This snake dose something sorta interesting. I can walk into my reptile room and look at this snake and he'll be jet black like in the first picture. I can walk back in 30min later and he looks like he dose in the second picture. In the second picture he was sprayed down but that was after he had already looked like that for an hour. He will do this color change a couple times a month. Some months it's a couple times a week.