Nevermind, I realized how stupid my question was! Of Course it was Dagon which was cursed!
So Akatosh cursed him then? That explains quite a lot if we are considering the theory that the other aspects of Aka wanted to destroy him to be free to eat the world again (the one they created a few days ago)
Magico, you should probably read some more of the texts. http://www.imperial-library.info/content/fight-one-eating-birth-dagon is th one with Dagon and Alduin.
Take a piece of candy, like a skittle. Throw it in your mouth and chew. You just imitated Alduin eating Mundus.
And remember, time consumes us all. Except that Alduin makes it a little more literal.
Wasn't it detailed in writing as him performing a sort of vacuuming-like technique? I'm quite sure he could easily just devour it whole, but from what I've read Alduin likes to take his sweet time.