John Belushi gets what could be a phenomenal movie career off to a soaring low-comedy start in "National Lampoon's Animal House," opening today at area theaters.

As Bluto, the resident insatiable slob at a happily disreputable college fraternity, Belushi suggests not so much a recognizably gross human being as an amalgam of unchecked appetites embodied in a vaguely human form.

It's difficult to think of Bluto as a person, even in the deliberately farcical, low-minded context of "Animal House." He's more like a filthy Force of Nature or a demented Id. Bluto seems to be in a permanent stupor from the gratification of his ravenous thirst, hunger and lust. Belushi's looks are ideal for the role: at once swarthy and cherubic, he suggests a baby sunk in dissipation.

Belushi also controls a wicked array of conspiratorial expressions with the audience. His smoldering pouts, crazed gleams, elevating eyebrows and erotically-contended smiles generate gleeful rabble-rousing excitement. And he can seem irresistibly funny in repose or invest minor slapstick opportunities with a streak of genius.

For example, his hilarious pantomining stealthiness during a nocturnal break-in at the dean's office. In the long run these subtle gifts of comic evocation should carry him further than frontal assault vulgarity, although it's obvious that both Belushi and this film will be long-remembered for Bluto's grossest stunt: smacking his stuffed cheeks to erupt a mouthful of mashed potatoes at the close of a sequence in which he has devoured food items at random in the school cafeteria. (In packed houses, the repsonse to Belushi's demonic clowning is so tumultuous that you seldom discern his occasional spoken - as opposed to grunted, growled and snorted - lines.)

Strictly speaking, Bluto is a minor character. It's unlikely that he would ever have loomed larger than the finished film unless someone as original as Belushi had been chosen to interpret him. As it is, Belushi's sensational impact may obscure the movie's abundance of fresh faces and adept comic performances.

For example, Tim Matheson as Otter, the fraternity smoothie and make-out expert, is just as impressive as Belushi, in a droll but unsensational style. In the smung but disarmingly likeable role, Matheson is as personable as Jack Lemmon in his best early roles, yet less eccentric and jittery in style. His performance may wear better than Belushi's since it doesn't depend on shock effect and isn't subject to the consequent strains of revulsion.

Between them, Otter and Bluto exemplify the two adolescent ideals of masculinity that one might have anticipated from the National Lampoon: unflappable, seductive boy-of-the-world on one hand; and recklse, self-gratifying bad-boy prankster on the other. Under the crisp, spirited direction of 27-year-old John Landis, who earned this winning crack at a block-buster on the strength of "The Kentucky Fried Movie," and anthology of film and TV spoofs, "Animal House" emerges as an enjoyable sophomoric farce, too episodic and shallowly derisive to inspire lasting esteem, but certainly a diverting, cheerful weekend blow-out.

The scenario, devised by National Lampoon stalwarts Doug Kenney and Chris Miller in collaboration with Harold Ramis, an actor-writer who worked on the Lampoon's radio show and theatrical revues, might have been called "M*A*S*H Goes to College." Otter and his best pal, Boon, played by Peter Riegert, are supposed to be members of the Class of 1962 at Faber, an apocryphal small Eastern college, but they're readily identifiable as the spiritual kid brothers or nephews of Hawkeye and Trapper.

Otter and Boon even had a golfing scene recalling they are in "M*A*S*H." The boys' target on this excursion turns out to be a yound tyrant named Niedermeyer, student R.O.T.C. commander and member of the despised respectable frat, Omega House. Don Sutherland, who played Hawkeye, has a small role in "Animal House." He plays the closest thing to an adult influence that the writers can bring themselves to admire, a sort of melancholy English professor who hosts a pot party and gets involved with Boon's steady girl, Katy, played by the lovely young actress Karen Allen. She made one of her first appearances in "The Whidjit Maker," a short story film produced in Washington.

(Ultimately, both "Animal House" and "M*A*S*H" appear to derive from one of Jack Lemmon's best and least revived vehicles, the delightful 1956 service comedy "Operation Mad Ball," which pitted fun-loving, ingenious enlisted men against a sneaky martinet officer played brilliantly by Ernie Kovacs. There was even a prototype four Bluto in "Operation Md Ball" - Mickey Rooney's astonishing comic bit as a frenetic, voluble non-com called Skibo.)

Although a rivalry is trumped up between the hedonistic Deltas and the square Omegas, who are ecouraged to sabotage by an uptight, autocratic dean (John Vernon stepping into the old Kovacs and Robert Duvall roles), the conflict never seems convincing as the belated revenge of free-spirited frat members on their straight-arrow brethren. On the other hand, it makes considerable sense as the mocking revenge that former campus misfits and outsiders get on the kids they perceived as socially secure and dominant.

Delta is the sort of hang-loose establishment that cards like Miller and Kenney may have wished they had operated from when they were college cynics, practical jokers and girl-chasers. The Delta message is basically an appeal of uninhibited feminie companionship - a solace that unconventional college boys find it difficult to attract and guarantee. Never mind those clean-cut squares who probably will end up with more money and better jobs, the movie seems to say. Come on over to Delta! That's where the real fun and the real guys can be found.

The strain in the material comes from the underlying cry of desperation beneath the superficial display of boyish confidence and superiority. Ultimately, the writers aren't secure enough to give a few breaks to the Omegas and shower some cleansing ridicule on the Deltas. The generous, unifying perception that informs a great original film comedy like "Citizens Band" can never break through the defense mechanisms of an "Animal House." At most, one detects fleeting hints of doubt, expressed here by the maturity of Katy, who keeps waiting for Boon to grow out of his dependence on the Delta camaraderie.

As Kenney, Miller and Ramis formulate the conflict, one can choose between going animal with the Deltas and vegetable with the Omegas. Within those terms, anyone with a zest for life would obviously make a beeline for Delta House. But projecting this dichotomy beyond adolescence or the limits of a knockabout farce begins to cause problems. It's one of the prejudices that seems to limit the comic vision of the National Lampoon, clever and entertaining as it often is. As magazine humorists, Kenney and Miller excelled at recalling and exaggerating teenage sex fantasies. Belushi's peeping-Tom episode in "Animal House" is a triumphant little example of the sort of thing they were best at. Whether they have deeper comic instincts remains to be seen. "Animal House" is likely to prove so financially gratifying that it may eliminate any incentive for probing deeper.

Under Landis' modulated direction, "Animal House" never gegins to run wild in a kinesthetic sense. There was more pulsation and movement in Robert Zemeckis' direction of "I Wanna Hold Your Hand."

Landis sets up outrageous, often vulgar, material with a methodical, unemphatic kind of wit. His neatness benefits both the jokes and the performers, allowing them to score cleanly, while attention clearly concentrated on the payoff in any given sequence. On the other hand, his formality can seem stilted, particularly with material so miscellaneous. Ultimately, "Animal House" has no more narrative momentum than "Kentucky Fried Movie." It too resolves itself into a cinematic revue, in which no skits are exactly shortchanged, but some are certainly funnier than others.

The most amusing subsidiary performers are Thomas Hulce and Stephen Furst as freshman pledges at Delta, Sarah Holcomb as a precocious party girl who hooks up with Hulce, Mark Metcalf and James Daughton as the leaders of Omega, James Widdoes as the nice house president of Delta, Bruce McGill (who played the hostile brother in "Citizens Band") as the mad motorcyclist of Delta and Sutherland, Vernon and Verna Bloom (cast as the dean's randy wife) in the nominally grown-up slots.

You may not care to take up permanent spiritual residence at "Animal House," but it's funny place to visit.