"Urban people have a lot of misconceptions about nature," said Lisa Bierer, a naturalist at the 30th Street Nature Center in Mount Rainier as she peered down at Jake the corn snake relaxing in his tank. "One lady swore these snakes bite onto their tails and go around in circles, and sparks shoot out of them."

The snakes and other critters that skitter, slither and slog around at the center run by the Maryland-National Capital Park and Planning Commission are often regarded with superstitious terror by urbanites.

Even the harmless little DeKay snakes Jake loves to snack on -- which the neighborhood youngsters bring in -- are victimized by lousy PR.

"They say these are 'baby copperheads,' or 'baby rattlers' -- they have to be 'baby-something-poisonous,' " Bierer said.

The 30th Street center -- a project in its 11th year and unique among the park commission's nature centers because it is set in the heart of an urban Prince George's neighborhood -- aims to dispel such myths and make local children and adults appreciate the nature in their own back yards.

"We'll take kids out in the woods and they'll be uncomfortable. Often urban kids will be scared of any leaves that rustle and any sound they don't recognize," said Marie Brooks, who directs the center for the park commission's Department of Conservation and Interpretation. "One of the basic goals here is to make the public feel at home with nature, at ease in the woods."

Patrick Perry, 12, cleaned cages as Brooks spoke.

"Some people are afraid to touch some of the animals because they aren't used to it," he said. "This is a place to come, learn about nature and have fun. It helps them get used to it."

Situated on a tidy working-class street, the center encourages local youngsters to drop in, get to know and tend the animals who live there, and talk about personal experiences with nature.

"You'd be surprised at the number of turtles people find walking along these streets," Brooks said. "You don't have to travel miles to get excited about nature. You can go around the corner from where you live."

But children who live in apartment complexes -- or come from single-parent households or those where both parents must work -- may lack opportunities to explore, she said. So a big part of the center's focus is on guided field trips.

"They appreciate that we'll put them in a van and take them someplace," Brooks said. "Some of them are not used to doing that with their families . . . We develop a personal rapport with the kids. They start talking about what they're seeing outdoors."

The children also bring in live finds -- including turkeys, ducks, turtles, snakes and beetles -- and dig for feeder worms for the residents. Feeding time is particularly popular at the center.

"Sometimes I think we could sell tickets for snake feeding; it's amazing," said Brooks, who came to work one morning and was shocked to find a boa constrictor in one terrarium. After the center had closed the previous day, park police found the stray pet boa crawling up a house, assumed it lived at the center, got someone to open the door and put it in the tank.

"Anything that's crawling around the neighborhood, they automatically think, 'Oh, an escapee from the nature center,' " said Brooks with a laugh.

Ann Howard, of College Park, dropped in recently to sign up her daughter Kim Henry, 10, for a summer camp program.

Howard, a teacher, said she thinks the center's emphasis on "firsthand experience" and its "hands-on quality" are "wonderful."

The center also serves other age groups as a base for a variety of activities, including nature hikes, bird-watching expeditions, guided tree tours through Mount Rainier, and motorboat rides on the nearby Anacostia River.

On one such recent tour, park commission naturalist Kerry Fitzpatrick took some local adult environmentalists -- members of the Friends of Sligo Creek -- from the historic Port of Bladensburg, not far from Mount Rainier, down the Anacostia to Kenilworth Aquatic Gardens and back.

The trip offered a seldom-seen glimpse of a natural environment that thrives within the green spaces of urban areas.

"You won't know you're in an urban area," Fitzpatrick told the passengers.

The boat passed banks lined with orange day lilies and Queen Anne's lace, as herons, osprey, barn swallows and geese swooped past. Even occasional reminders of civilization -- a rusted 1950s convertible half submerged in the river bank, a toy football, plastic shards, and tires occupied by sunning water turtles -- didn't seem too intrusive on the surprisingly peaceful urban waterway. The boat also passed occasional leaping carp and an active beaver lodge.

Just up the road from Bladensburg, the park commission, with the assistance of the 30th Street center and local volunteers, is developing a 10-acre marshy woodland site in Colmar Manor for a walk-in nature study area. It will be the focus for canoe trips and other explorations of the natural environment.

The 30th Street Nature Center is at 4210 30th St. in Mount Rainier. For information about summer hours and programs, call 927-2163.