Question: In the pond scene, after the shark attacks the poor man on the paddle boat, why didn't he go after Michael too? He just swam past him, sparing him.
Chosen answer: The horror of "Jaws" was not so much the physical trauma of being eaten alive as it was the terror of not knowing who would be next. So, we see the panicking pier fisherman spared although the shark could have easily taken him; we see the shark randomly select the Kintner boy while sparing hundreds of other terrified people in the water at Amity's public beach; and we see the shark just barely spare Michael after eating the man in the pond. Although he wasn't physically harmed, Michael was hospitalized in shock after the encounter with the shark; so, he obviously suffered unimaginable terror. It's that "almost eaten" factor that sells the film. Captain Quint's story of the USS Indianapolis drives home the point that waiting to be eaten is as terrifying as actually being eaten, and that's what film maker Steven Spielberg very successfully conveyed all throughout the movie.
Answer: Excellent answers, and just to add one more point: the shark in the movie is not a normal one. He doesn't act just out of hunger, but also out of sheer malevolence: in fact, just like in the novel, it's implied there's *something* about him, something almost supernatural. He may have spared Michael because he had just secured a meal, to escape the gathering humans before they can harm him... or because killing the boy wouldn't have entertained him sufficiently.
I always assumed the opposite: the shark, when all is said and done, is just an animal following its base instincts. It has no sense of right or wrong; it just does what comes naturally to it, and it only kills and eats to feed itself. After eating the guy in the rowboat, the shark is no longer hungry, so it leaves Michael and his friends alone.
Answer: In addition, the original scene called for Michael to be in the arms of the man, with the man in the jaws of the shark. Michael is carried across the water and the released by the man just before the shark takes him under. Spielberg ultimately felt that this was over the top gruesome and changed the scene.