An iridescent alligator and fanciful giraffes, bears and birds shared the stage with the Utah Symphony Saturday, for the final Youth Concert of the season."Walk With the Animals and Talk With the Animals," was the invitation issued to children by Associate Conductor Christopher Wilkens. The symphony looked inviting, indeed. There stood the conductor in a yellow cap and brown walking shoes, with a slide show behind him, surrounded by the orchestra which was, in turn, surrounded by papier-mache animals.

The orchestra played six short selections. And the children, who filled Symphony Hall for two performances, watched and listened intently.

The three-concert youth series has been sponsored by a grant from Mer-vyn's.

The Hogle Zoo also had a hand in Saturday's program. Docents roamed the lobby of Symphony Hall before the concert, letting children touch the various small mammals, reptiles, and birds they carried.

In addition, the zoo provided the slides which accompanied "The Swan" from Saint-Saens' "Carnival of the Animals."

The appearance of Utah Symphony Youth Guild Competition winner Sam Aikele from Arco, Idaho, gave all the young pianists in the audience something to aim for. He played the first movement of Gershwin's Concerto in F.

Between selections, Wilkens spoke informally to the audience. (He even munched a banana as he introduced the musical story of train trip through India which ended in a train station swarming with monkeys). "The orchestra will make swirly sounds like ocean waves," he explained as he introduced Hovha-ness' "And God Created the Great Whales," which featured recordings of the calls of humpback whales.

To illustrate Poulenc's musical story of "Babar the Little Elephant," Wilkens introduced Harry the elephant trainer. Harry, dressed for safari, read the children's storybook while the orchestra played and slides of the actual De Brunhoff illustrations (on loan from the Seattle Symphony) flashed above.

It was very entertaining. As was the final animal selection: Caillet's "Pop Goes La Weasel." "We need a very special instrument in the percussion section for this most famous animal selection," said Wilkens, pointing to three balloons, which the balloon-player (or is it balloonist?) popped at the appropriate moment.

Season tickets for next year's Youth Symphony are available now. Performances will be at 10 and 11:30 a.m. on Saturday, Oct. 22, Feb. 25 and April 15. Prices for the season are $5 for children and $10 for adults with a $29 family pass available. Single ticket prices will be $2 for children and $4 for adults. For more information call 533-6407.