Why Do Wolves Howl and werewolves act wild and turn to wolves at Full Moon?

I have never seen a very satisfying explanation of that question. In fact, I'm not sure just why they howl at all. Of course, wolves in the wild hunt in packs. So howling might be a way of telling each other where they are.
I can't think of a good reason why a full moon would make any difference. I wonder if that part is really true, or maybe theres a whole legend about wolves and full moon.

please leave your comments if you know the relation or just come up with something interesting ! be creative =}