The apes at Lincoln Park Zoo are finally getting a chance to take their revenge on people who for years have been pounding their palms against the glass walls of the primates' old home.

At the zoo's new Regenstein Center for African Apes, chimpanzees can touch a panel hidden from public view that will shoot harmless bursts of air at unsuspecting visitors.

"You often hear about chimps spitting or throwing," said Steve Ross, a behaviorist at the zoo. "They do that to get a rise out of the public. This gives them that opportunity but in a safe way."

The feature is one of many in the 55,000-square-foot habitat meant to help people connect with their primate cousins.

Lincoln Park Zoo was already renowned for its primate breeding success, with 45 gorilla births since 1970. With its new facility, which opened July 1, it joins a growing number of U.S. zoos striving to make exhibits more exciting for people and more natural for the animals.

Zoo officials hope the exhibit's realistic environments will give visitors new respect for apes and allow scientists to observe the apes acting as they would in the wild.

Its predecessor, the Lester E. Fisher Great Ape House, was dark and cavernous, but the $26 million Regenstein Center, the most expensive facility ever built at the 35-acre zoo, is spacious, airy and green. A downed tree forms a bridge that apes can use to cross a waterfall, and mulch-covered floors imitate a natural forest and are gentler on apes' joints.

The zoo's 24 apes can climb trees and see the John Hancock Center to the right and Lake Michigan to the left.

The primates also can control fans hidden in boulders, helping them moderate the effects of Chicago's muggy summers and icy winters, and touch panels in fake tree trunks that will catapult snacks toward them.

Many zoos are striving to make their ape exhibits more natural and interactive to serve an increasingly sophisticated public, said Diana DeVaughn, spokeswoman for the Louisville Zoo in Kentucky, which won a top American Zoo and Aquarium Association award last year for its gorilla exhibit.

The Los Angeles Zoo made its ape exhibit interactive by letting the animals pull ropes to ring bells near visitors or spray water at people, said Jennie McNary, the zoo's curator of mammals.

"The chimps were smart enough to figure out they could startle people with it," she said.

Zoo officials hope the habitats will help visitors feel physically and emotionally closer to the apes, Lincoln Park Zoo director Kevin Bell said. Connecting with the animals could inspire people to care more about helping apes in zoos and in the wild, he said.

Only 375 gorillas live in U.S. zoos, and 40,000 to 100,000 live in the wild, said Steven Thompson, zoo vice president. Experts suspect that the wild gorilla population has declined 30 percent to 50 percent in the past 15 years because of hunting and damage to their natural habitats.

"They're so close to humans," Bell said. "Yet there's very few of these animals left in the wild."