Alligator snapping turtle. He wants to eat you. Can weigh between 155 and 175 pounds. There is an unverified report of a 403-pound (183 kg) Alligator Snapping Turtle found in Kansas in 1937. (Thanks, Wikipedia!)
Shot through glass. Inside. On a cloudy day. Without a tripod.
It's not actually hard to get a shot of him with his mouth open. He's like that most of the time. I think he's waiting for some unsuspecting child to fall through the glass somehow. "One of these days... "