The largest groups on both sides of the abortion issue got a chance to have their say yesterday as Senate hearings on a controversial bill that would declare life begins at conception came to an emotional and inconclusive end.

The results were predictable. Anti-abortionists, who support the bill, contended that snail darters, dolphins, whales and even eggs of the poisonous Gila monster receive legal protection not given unborn humans.

The other side countered that the bill, which would outlaw abortion by giving the unborn protection of due process of law under the 14th Amendment, would make women "incubators for the state" and put them back "in the dark ages."

Sarah Weddington, former White House adviser on women's affairs, presented the case for 75 groups, with memberships totaling 34 million, that support legalized abortion.

Weddington, who successfully argued the 1973 Supreme Court case that opened up legal abortion, said it was "inconceivable" that Congress would pass a bill "which so blatantly disregards the integrity of the constitutional process, the separation of powers, the religious liberty of our citizens, the will of the people, the sound practice of medicine and the desperate needs of women facing problem pregnancies."

She and others accused Sen. John P. East (R-N.C.), who chaired the hearings, of conducting a stacked inquiry that ignored testimony from the women most affected by the proposal.

Rep. Henry J. Hyde(R-Ill.), co-author of the bill and one of the nation's leading anti-abortionists, praised East for enduring "an incredible display of journalistic abuse" and called him a champion of "the defensless, voiceless pre-born." Hyde charged "widly confused" opponents with using "scare tactics" to describe the bill.

But the most compelling testimony in the eighth day of hearings on the bill came from singer Judy Collins and Dr. Carolyn F. Gerster, former chairman of the National Right to Life Committee.

Gerster, a mother of five, said she had joined the anti-abortion movement after she had a miscarriage during the 13th week of pregnancy while alone in her office. With tears in her eyes and her voice cracking, she told how she had been overcome with emotion when she found she had miscarried a "perfectly formed 3 1/2-inch baby boy."

"Later on, when abortion mills were running like car washes, I thought that if I as a physician and mature woman didn't understand the development of a 13-week-old, how can all these 15-year-old girls getting abortions know what they're doing," she added.

Collins, speaking in a resounding theatrical voice for abortion, said she was testifying for "the women who have no voice in this room." She read a series of dramatic letters from women relating the anguish they went through after they had given birth to children with genetic diseases who died in early childhood and a newspaper column by Tom Braden about how his daughter had an abortion after she was repeatedly raped.

East, reminding the packed hearing room that he is paralyzed by polio, said "eliminating the handicapped" from a chance for life "smacks of a Nazi-like mentality."