Spring, Summer, Fall, Crawdad colors?

What triggers them to change colors? Is it temp, weather, season, Moon, ??? And What are all the different colors that they change to? {John}

I am not an expert but here is what is known to me to be fact…
The lunar table plays a significant role in crayfish color and shell development.
Environment governs color more so than lunar effects.
The way is works is that the colors pallet that they go through is based on environment while transition / growth dictate the phase. The intensity of there color being dictated by the duration since there last molt. The lunar table being one of the deciding factors as to when molt occurs. In a nutshell they start off in a milky or dull color and as the shell thickens (made mostly of calcium) they get brighter in color. This is not always true but generally speaking it is. Side note, they are able to change color as well. I only offer this since the crayfish you find in a bait show will almost not ever be the same color as in the river.

The more I explain the more questions I have.. Moss Boss,
You are the Science Guru, can you offer any insight.
Jc