Guide with a Weird Shape Tween Question

I was wondering if anyone knows how they did these little flare thingy’s. I know how to make a shape follow a Guide Layer but how do you get the shape to morph like these do:

http://www.cirquedusoleil.com/CirqueDuSoleil/en/spectaculera/saltimbanco/saltimbanco_home.htm

click enter and look at the flares going up the left side, If anyone know of a tutorial the gives a basic idea of how to do this that would be cool too!

Thanks,
Josh