Fiddler Crabs changing color

[BJG]

I have two fiddler crabs, two males and two females. When I bought the crabs, they were all the same dark brown-black color. Recently, like in the last few days, the larger male and the larger female have changed color. They have both developed a MUCH lighter tan color, almost like a sand color, on the upper half of their backs. I know that they will change to a whiter color before they molt but is this the same thing? Is this normal? The other two crabs have maintained their dark colors.

 

[SamuraiGaidin]

I have 2 fiddler crabs. The female molted and now has the same sand color. The male has not molted and is really dark. The male was larger from the store but the female has out grown him. Hope this helps.

Nothing in reality makes sense except in the light of magic.