• Blood in the Water, 9-11 p.m. Sunday, Discovery Channel

• Defying Gravity, 9-11 p.m. Sunday, WPLG-ABC 10

Conversation I heard in Hollywood last week (or maybe just dreamed; but in television criticism, like horseshoes and hand grenades, close is good enough):

Programmer No. 1 -- I don't know what's with these viewers. We give 'em quality stuff all summer long -- Botoxed South Beach swine, drunken New York preppies, even dancing fat people -- and still they ain't watching.

Programmer No. 2 -- Yeah, and it's August already. We've got no choice but to go for the doomsday weapons -- shark attacks and naked chicks bouncing around in zero-gravity.

Thus is explained Sunday night's programming choices. Blood in the Water is the Discovery Channel's cheesy but diverting documentary on the rogue white shark whose vendetta against New Jersey inspired the novel and film Jaws. And the sci-fi series Defying Gravity is ABC's sensitive and thought-provoking exploration of the theological implications of naked chicks bouncing around in zero-gravity.

`BLOOD IN THE WATER'

Blood in the Water -- which kicks off Discovery Channel's annual Shark Week chewfest -- is the long-awaited answer to the question, ``What the hell was Richard Dreyfuss talking about in Jaws when he screamed at the mayor, `It's gonna happen again! It's happened before! The Jersey beach! 1916! Five people chewed up in the surf!' ''

Turns out this was not just the product of some screenwriter's fervid imagination but a real incident. In the middle of a brutal summer heat wave that sent thousands of bathers to the New Jersey shore, a rogue shark began stalking the beaches, killing four swimmers and mutilating another in a span of just two weeks.

The resulting hysteria -- newspapers from coast to coast sent reporters to Jersey in a media feeding frenzy that would make today's cable-news nets weep bitter tears of envy -- was all the greater because the fatal shark attacks were the first ever recorded in American coastal waters. The conventional scientific wisdom of the day was that sharks were too chicken to go after people, and that even if they developed a set of ichthyological cojones, only a giant great white shark would be physically capable of eating a human. And everybody knew great whites stuck to the warmer tropical waters down south.

After the first attack off Beach Haven, N.J., a scientist from the American Museum of Natural History stuffily proclaimed it ``a hoax or a misunderstood drowning rather than the work of a killer shark.'' Other theories -- though scarcely less comforting -- painted giant snapping turtles or homicidal schools of mackerel as the villain. Some even thought German U-boats in the Atlantic (World War I was dragging into its third year, with no end in sight) had somehow deranged marine life.

Just like one of those old horror movies where the villagers know there's a damn vampire no matter what the hare-brained local professor says, regular New Jersey folk caught on quicker than the eggheads. After the shark entered a tidal inlet and journeyed several miles up a freshwater creek to kill two people and soundly chew a third, the residents of the little town of Matawan spent days tossing dynamite and firing random bullets into the water.

That touched off a shark-hunting holocaust all along the coast that resulted in the deaths of hundreds of the creatures -- including the probable culprit, a young great white beaten to death by a Barnum & Bailey lion tamer (this whole sentence is like PETA's worst nightmare, no?) who was out fishing when the thing tried to rob his catch.

Flabby and repetitive, shot as a series of re-created scenes rather than as a conventional documentary, Blood in the Water is nonetheless saved by the pure visceral fascination of its story. The main question I had after watching it was, how in the world did it take almost six decades before somebody made this story into a movie?

`DEFYING GRAVITY'

Less rhetorical and more easily answered is the question prompted by Defying Gravity: Why would an astronaut on her way to Venus suddenly take off her space suit and float naked into an airlock? I'm running out of room to answer it here, but call my friend Mr. Nielsen for the full explanation.

Debuting with a two-hour special before settling into a conventional 60-minute format, Defying Gravity is startlingly similar to Virtuality, an unsold pilot that Fox aired as a movie earlier this summer: Eight astronauts on a six-year space voyage, including the requisite number of covert nut cases and perverts. Mission control keeping an ominous secret from the crew. Inexplicable physical and mental breakdowns as the ship speeds further into space. And nonlinear storytelling, with so many flashbacks and flash-forwards and dream sequences that pretty soon you can't even remember the last time you saw a naked chick bobbing around the cabin. My advice: Rent Barbarella instead. Jane Fonda's spacesuit striptease is right at the beginning, so it's easier to hit rewind.