Absolutely fantastic game! Really hit it out of the park. I cant think of any way I would improve things except that the music loop is a bit jarring in the way it goes from the end back to the beginning.
I love how you have one basic concept, move with left and right, and everything revolves around that. I also love how you've managed to use your extra features (bouncing off boats, eating people, firing) to create as much dynamic and emergent gameplay as possible. You're giving an incredible amount of ability for such a limited amount of time.
So far this is the best one I've played!