Actually, there are already alternate skins in the model viewer for the arcane serpents. They've got splotches of a lighter color down their bodies.

Only thing about the models are the fins are unfinished and still have black around where it needs to be transparent, they're also overall darker then the normal serpents. So, they could still do something neat with those one day!
Spirit Beasts are always a roll of the dice. You just never know what we're gonna get.
[Also, Arcane Wyrm lovers, if you're curious to peek at the skins of them and have the current model viewer, they are listed under 'netherdragon' and the skins I'm talking about are listed as 'netherdragonlightingX'. X=color.]