AT HIDDEN POND Nature Center in Springfield, the record for most slugs held in one's mouth is 36. Assistant naturalist John Lewis, aka Sluggo, will attempt to top that at Sunday's 15th annual Slugfest, the center's salute to the snail's shell-less relative.

The event, on Hidden Pond's shady, sloping green, resembles a renaissance fair in both its activities and the way the cast -- here, mostly the center's teen volunteers -- acts like the affair is nothing out of the ordinary.

Booths with crafts and contests invite visitors to touch slugs, sometimes escalating to a Sluggo-style dare. Strolling minstrels, the Slug Troubadours, sing lyrics written by acting park manager Mike McCaffrey, the zany muse who also pens the original Slugfest play every year. In lieu of jousting, the main athletic competition is the slug derby; upon arrival, each registrant is issued a slug to enter in the races.

The afternoon's narrative is shaped by sparring royals: the Slug King and Slug Queen vs. "the enemy of all slugs," Captain Salty, who sports a pirate hat and brandishes a canister of Morton's. Later, he sticks his neck through the Slime Toss board, while visitors -- egged on by the jeering slug royalty -- hurl chunks of gelatin at his face.

With face painting and games of chance, Slugfest offers accessible entertainment for youngsters, but the event is also designed to help kids who like animals understand why their habitat is so precious. "My kids are just crazy about nature," says Kathy Holtgrieve of Springfield, whose 12-year-old daughter, Sally, is a center volunteer and whose 8-year-old son, Jackson, will be at his second Slugfest.

Some of the young environmental enthusiasts grow up to be the center's teen volunteers, and in Lewis's case, join the staff. They use Slugfest's carnival atmosphere as a medium to share their passion for ecological stewardship and study, just as they have absorbed it from the center's leaders.

"Slugs are misunderstood," says Slugfest founder Clara Ailes, an assistant naturalist at Hidden Pond since 1984. "We need to learn about them and appreciate them."

When most Slugfest visitors have arrived, she dons a lab coat to become Professor Clarissa McSnails and leads the crowd inside to the center's largest classroom. Children sit on carpet squares, and Ailes explains slugs' anatomy, diet and roles in the ecosystem.

Box turtles, northern brown snakes and firefly larvae eat slugs, "so if we didn't have slugs, we wouldn't have lightning bugs," Ailes says. Locally, there are two main types of slugs. The gray garden slug is likely to munch on garden plants such as hostas, beans and chrysanthemums. The other, the smaller tawny slug, feeds mostly on waste and dead plant matter and actually helps clean up the garden. "Much maligned, poor little tawny guy," Ailes says.

Ailes got the idea for Slugfest from a newspaper article about a slug festival on the West Coast, one that also featured a slug king and queen but was for adults with a bacchanalian bent. ("To tell you the truth, they got drunk and had cooking contests," she says.) Hidden Pond's staff wanted a special focus for each season, and since there are camps in summer, an abundance of school groups in spring and an animal costume dance near Valentine's Day, she and McCaffrey developed the Slugfest concept for fall.

The festival has evolved over time, but the piece that is different each year is McCaffrey's original play, which emphasizes slug appreciation and information on an obscure non-slug-related nature item. The play is often a spoof on a popular movie; previous titles include "The Slug Whisperer," "Crouching Slug, Hidden Salt" and last year's "The Slime of Music."

Earlier this summer, McCaffrey had planned to write "Casaslugga," about a slug-friendly homeowner named Rick, his ex-girlfriend Ilsa and his pianist friend Sam, who plays "As Slime Goes By." "But," McCaffrey says, "my daughter complained, 'You had Nazis last year.' And I said, 'They weren't Nazis; they were pesticide workers!' "

In the end, he decided to riff on a more lighthearted story, so this year, the play is set in the fictional town of Tayberry, named for the real blackberry-raspberry hybrid fruit created in Scotland in the 1970s. The town's sheriff bears a striking resemblance to an Andy Griffith television character.

Along with the play, the slug derby is one of the festival's most popular events, with heats throughout the afternoon. Slugs start inside the bulls-eye center of a large circle marked on a board, and the first tentacle across the circle's perimeter wins. Each heat can occupy a decent chunk of children's time and attention.

"Those are hilarious; they take 15 minutes," says volunteer Arthi Aravind, 14, of Springfield.

When kids spend an afternoon watching their invertebrate charges, whether in the race or as they crawl across their toes at the slug foot massage station, a bond forms, Ailes says. "They develop, you know," she pauses, tapping her heart, "a love for them."

At the end of the day, participants can release their slugs near the eponymous Hidden Pond or take them home as a pet, potentially to return next year. Inspired by Cabbage Patch dolls' paperwork, Ailes created a fact sheet and adoption form to aid the slugs' new owners.

"Unfortunately, we always bring a slug home," says Diane Bettge, whose son Thomas, 15, is a volunteer and whose younger children, 6 and 12, have learned the drill from Slugfests past. "They are outside pets."

SLUGFEST -- Sunday from 2 to 4. Hidden Pond Nature Center, 8511 Greeley Blvd., Springfield. $4. Reservations required. 703-451-9588.

John Lewis, aka Sluggo, will be up to his usual antics at Sunday's Slugfest. Allison Van Gilst prepares to reign as Virginia Slug Queen at the event at Hidden Pond Nature Center in Springfield.