I've never liked this idea. If he was eating himself from his tail, then he would chomp all the way through himself until his mouth is eating his mouth. Leaves no room for creation.
I think an image of a circle not entirely completed by the serpent would fit better. think of it like a clock - normally with the snout of the mouth at one side of 12 'o clock, and the tip of the tail at the other side of 12 'o clock. If the tail started at 12 'o clock, and the mouth reached around to, say, 3 'o clock, and everything continuing from 3 to 12 being 'creation', then that allows the dragon to keep moving in a circle, devouring creation as he goes, and leaving a trail of new creation behind him (up to you to imagine where that might come from).
But meeting his own tail with his mouth means he's only eating himself. So he either kills himself, or doesn't eat anything in order to stay alive. Or, he can't quite reach far enough to actually take a chomp out of himself, and http://www.youtube.com/watch?v=qe9KaCy_jGE. But to eat himself while still retaining his whole self... doesn't make sense.
Just my random thoughts on the image