The basic story is always the same, zombies, in hordes or individually roam across the landscape eating everything in sight. There are two takes on this however, one says the dead will eat everything living they come across including animals and humans. and may include insects or plants but I have yet to come across that in the fiction. There are also those who say the dead only eat humans.
Shark Biter is an interesting zombie in that he seems to illustrate on screen the first of those two ideas, that zombies will eat whatever they come across. We’ve seen this other places where horses, dogs, cows and things have been chomped on by the dead but the question is whether or not they would really eat anything.
I kind of picture a bunch of university kids kicking around the story and saying things like;
A: “Would they eat a dog?”
B: “Sure, sure.”
A: “What about a fish?”
B: “Yeah, sure. Why not?”
A: “So, basically what you’re saying is that if a zombie came across a shark in the water, the zombie would try to eat the shark?”
B: “Sure, I guess, but that probably wouldn’t happen very often right?”
So what Fulci gave us in this scene from Zombie 2 is a simple visual cue of what is likely to happen in the case of a zombie apocalypse. Do we see it very often? No, because it doesn’t happen very often just like humans don’t run into sharks in their daily lives very often. So silly as it is, it makes a sort of sense.