I really love this one. I think the DOF is great, a little deeper would be nice but I doubt it was possible at the distance you shot. You used the rest of his body out of focus to fill the frame nicely which I thought was a clever way to fulfill the challenge. Zooming in on just the head of the snake wouldn't be enough, you need to see it's body, and you did that. Nicely done.
I know it is imposible to change but that little triangle of light is distracting. You should have told him to curl up tighter to get rid of the space :P Great shot, awesome textures and scary look in his eye :)