The concept of different "movie universes" that Scott brought up is one of my favourite tropes: the "Celebrity Paradox". For example, in the Batman movies, Batman and other DC comics presumably do not exist. Or in the Harry Potter, all those actors from Alan Rickman to Helena Bonham Carter to David Tennant don't exist either. What's fun is when complications arise out of references being made to films that should not exist in those universes. For example, In White House Down, tour guide Donnie makes reference to the White House being destroyed in Independence Day - which was directed by White House Down helmer Roland Emmerich. Or in Fanboys, a movie in which the Star Wars franchise is central to the plot, Star Wars actors show up in cameos as different characters: Carrie Fisher as a doctor, Billy Dee Williams as Judge Reinhold, and Ray Park as a security guard.
Also, there is a shark with a toothed "snout", the sawshark. It's already been mentioned earlier on in this thread but here's a picture: