Character Analysis
Marlin and Dory run into these great big predators just a few minutes after leaving the safety of the reef. (We guess Marlin wasn't so crazy to be panicked about the dangers of the ocean, was he?).
Of course, it turns out there's no need to worry because Bruce, Chum, and Anchor are vegetarian sharks:
BRUCE/ANCHOR/CHUM: I am a nice shark, not a mindless eating machine. If I am to change this image, I must first change myself. Fish are friends, not food.
Well, that's a relief. Like the vampires in Twilight who don't kill humans, these guys are no danger to their little fishy friends.
Until, of course Bruce gets a little whiff of blood and goes into a feeding frenzy. Oops.
Mainly, these guys are hanging around to help Marlin and Dory find the diver's mask with the address written on it…and then to promptly lose it while trying to escape. (So much drama right out of the gate.)
Fun fishy fact: Bruce's name comes from another oceanic film—Jaws. While filming Jaws, Steven Spielberg named the various mechanical sharks on set Bruce after his lawyer, Bruce Ramer.