Waterworld/Headscratchers


 * The only other living thing we see in practically the entire movie is a giant... fish-eel thingie that the Mariner lures and kills for food. Seriously, what the hell was that thing?
 * The novel referred to it as either a "sharkphin" or "whalephin", memory's fuzzy. Apparently it was an escapee from Avatar: The Last Airbender before that series even existed.
 * For that matter, why does this fish-thingie have a vertical mouth? No mammal has such a thing, nor do any known shark or even fish. The creature could be a mutant, but what would be the evolutionary advantage of such an up-and-down mouth?
 * For that matter, do the other large sea animals such as sharks, whales, orcas, still exist, or were they wiped out by giant weird fish?