Although Jaws has a trio of fantastic leading men, there's no doubt that the star of the show is the shark. It's on the movie posters. The title of the movie is, obviously, a reference to it (in fact, many people think "Jaws" is the name of the shark). And it's the thing everyone came to the theater to see, even if it's currently "between projects," as they say.
Although the shark is famously portrayed—in true movie monster fashion—by three animatronic sharks, it's also portrayed with real footage of great whites in Australia, giving the film at least a small element of documentary realism. The scene of a shark tearing apart Hooper's empty cage is one example. In fact, although this shark just happened to swim by and get tangled in the cage, the director loved the footage so much that he made a serious plot change so he could use the footage. Since the cage was empty at the time the real shark attacked it, Hooper had to have escaped. So they decided against killing off Hooper, which had been in the original script like it was in the novel (source).
Granted, the 25-foot shark in Jaws is much larger than a typical great white shark; they usually max out at around 20 feet long (source). But such a shark could in theory exist in real life, which makes the idea much scarier than, say, the Creature from the Black Lagoon, which could not (we hope).
What about the shark makes it such a captivating character? We think it's in Spielberg's deft parallel portrayal of the shark as both a ferocious animal and a terrifying, otherworldly monster.
The shark is, obviously, a shark—an animal documented and classified by marine biologists across the world, not some kind of alien or mutant or tentacled monster. Hooper gives us the basic shark lifestyle info:
HOOPER: Look, the situation is that apparently, a Great White Shark has staked a claim in the waters off Amity Island, and he's going to continue to feed here as long as there is food in the water […] A shark is attracted to the exact kind of splashing and activity that occurs whenever human beings go in swimming. You cannot avoid it. […] what we are dealing with here is a perfect engine, an eating machine. It's really a miracle of evolution. All this machine does is swim and eat and make little sharks, and that's all.
The idea that a shark might prey on people is unfortunately but solidly grounded in reality. As one of a relatively few animals known to be man-eaters, sharks understandably fascinate people and scare them to death. During the opening credits, as the camera follows the shark's POV as it pushes through a forest of seaweed, it feels like we're watching a tiger stalking through the jungle. But it's just instinct and survival, just what sharks do, not malicious, planned, or vengeful.
Still, the shark in Jaws is also more than just a shark. This becomes clear from the first attack, where we don't actually see an inch of him. The fact that the shark isn't onscreen for much of the movie was a combination of serendipity (malfunctioning animatronics) and calculated mystery. In the case of the first attack, Spielberg said, "I really wanted to do it without seeing the shark […] I wanted the violent jerking motions to just start to trigger our imaginations into either thinking about what's happening below the surface of the waterline or blocking what was happening below the surface." Carl Gottlieb added, "In 1975 nobody had seen a big shark like that in a movie. Ever. We were able to hold it back [while still showing] the evidence of his strength, and the blood, and death that he caused" (source).
As a result, during that first scene, for all the audience knows Chrissie Watkins is getting tossed around by a ghost or King Kong or a dinosaur. Her attack looks like a demonic possession as much as anything, what with the screaming and thrashing and almost levitation-like effects. The shark's portrayal as an evil, menacing spirit is reinforced when Hooper compares it to Jack the Ripper. And when the shark rams the Orca, interrupting the men's singing, the effect is much like what we would see in a haunted house movie: banging floorboards, flickering lights, clattering cupboards, smashing glass, and spreading fire.
This shark isn't just hungry; he's seems to be a fish on a mission. It's as if he's trying to get revenge on the crew of the Orca and specifically on Quint, who's been killing sharks his whole life. It's this angle that's drawn comparison between Jaws and Moby Dick. Any ordinary shark would probably have concluded that the best option would be to get as far away from this boat and its harpoons as possible. Instead, it toys with the Orca, swimming underneath it, towing it out to sea, relentlessly and methodically returning and attacking until it gets its retribution. It's as if it has an intelligent and diabolical plan.
Look closely, and you'll find lots of other descriptions of the shark that scream "supernatural."
QUINT: You know the thing about a shark. He's got lifeless eyes, black eyes, like a doll's eyes. When he comes at ya, doesn't seem to be livin'. Until he bites ya and those black eyes roll over white.
After the shark manages to submerge with three barrels, Hooper asks:
HOOPER: You ever had one do this before?
QUINT: I don't know…
HOOPER: He's chasing us! I don't believe it!
So is the shark of this earth? Or something more? The short answer might be "yes," and that's got to be why he gives us the heebie-jeebies. That and those big ol' pearly whites of his.
This just in: Reports have reached Shmoop suggesting that Bruce the Shark resented having so little screen time in the film and managed to protest by photobombing another shark actor's 15 minutes of fame.