This is in regard to the sharks who were trying to give up eating fish.
Could a shark live on foods other than fish? And if so, what things would they have to eat as a substitute.
Sharks have a wide variety foods they eat. Great white sharks will eat seals, penguins and whale carcasses as well as fish, for instance. The largest living shark, the whale shark, survives by eating some of the smallest ocean dwellers, plankton. Many sharks subsist largely on fish only because fish are so plentiful.
Specifically with regard to Finding Nemo, no, sharks can’t be vegetarians. However, believe it or not, some piranhas are vegetarians.
Yeah, I did think about plankton. But even if a shark gave up fish, is there any kind of shark that could go vegitarian or just live on plankton? I highly doubt it, but I still feel like asking anyway.
Oops, my last reply to to Q.E.D. but it looks like Earthling answered my second question before I even had it posted.
Who says they were vegetarian? I figured they were getting along by eating dolphins, seals, turtles, seabirds, humans, or other non-fish animals.
Well, this is getting into Cafe Society territory, but I just assumed that since in the movie, all animals have human like intelligence, and since the sharks had a moral qualm about eating fish, that they would more than likely have a moral qualm about eating any other living intelligent creature.
Perhaps they don’t consider non-fish to be “living intelligent creature[s]”.
There are humans who think nothing about dining on cows and pigs, but would never dream of eating a dog or cat.
Although in the movie all animals, whether mamals/reptiles/amphibians or whatever had human like intelligence, I guess I can see your point too.
My first thought was about cats.
Cats can’t be vegetarians; they require amino acids and suchlike that are only found in animal proteins. They HAVE to eat meat; textured soy won’t cut it. Cats fed on vegetarian dishes will develop nutritional deficiency diseases, and die.
I have no clue whether or not sharks would live or die on textured soy baby dolphins or whatever…
This isn’t strictly true. Cats do require the amino acid taurine, which their bodies cannot manufature. Taurine is found abundantly in meat, but is scarce in plants. However, synthetic taurine can be added to vegetarian feed for cats to fulfull the animal’s nutritive requirements. Nevertheless, cats fed a strictly vegetarian diet will seek meat on their own at any available opportunity, often escaping to go outside and hunt birds or small mammals. In short, although it is possible to raise a cat vegetarian and have it be physically healthy, doing so is needlessly cruel to the animal, IMO.
Cecil on vegetarian cats and dogs. He says pretty much the same thing that Q.E.D. does.
Ah. I stand corrected. Ignorance has been met, and reduced.
Although I have to agree that trying to make a cat live on vegetarian food is nuts, so to speak…
Explain the seagulls, then. 
“Mine! Mine! Mine! Mine! Mine!”
Of course, since the whole point of the “Sharnks Anonymous” program was to change the image of a shark as a “mindless eatin’ machine,” eating non-fish meat such as seals and humans and whatnot would still be unconductive. But hey, it’s just a movie, you really should relax…
Interesting; I assumed they were just suffering constant and frequent relapses.
I think the seagulls, given their stupidity, might be their food of choice if they were sticking to not dining on things with human like intelligence. 
There are sharks that live on small things like shrimp and plankton and whatever tiny fish get vacuumed up (rather like whales). Whale sharks and megamouth sharks are filter-feeders.
http://www.fish.wa.gov.au/rec/broc/fishcard/whaleshk.html
http://www.flmnh.ufl.edu/fish/Gallery/descript/Megamouth/Megamouth.htm
I believe that the seagulls were saying “mate”, rather than “mine.”
IMHO
When they say “plankton,” doesn’t that include tiny fish?
They were. I’ve noticed a few people thinking it was “mine” though…