Animate multiple objects with the same animator (2D)

Hello! I've started to play around a bit with the new 2D features in Unity 4.3 and managed to import sprites, animate them (although I still haven't figured out how to make an animation last longer) and started to make simple state machines. I've watched the official Unity 2D video tutorial and downloaded the Bridge Defense demo to see how things work; but there's one thing I can't understand:

I have some gameObjects (some tubes) instantiated form a prefab which has an animator attached to activate the animation; my animation is just the tube filling with water, my problem is: when I tell the animator to activate the animation (done with a True/False boolean), all the tubes start to play the animation at the same time, which is logical considering that the animator is the same for all (is it right?). What I want to do is to activate the animation of each tube after the last tube's animation is over. How can I do that? Do I have to make a different animator for each tube?

My tubes are objects with a sprite renderer by the way, and I created the animation by just putting each image next to the other.

P.S The Bridge Defense demo also instantiates enemies from a prefab with an animator attached but it wasn't useful for my problem because each object just starts its animation when it's instantiated (which is what I don't want to do).

Any advice? Thanks in advance ;)