A large brick building with a pair of sliding doors, you step through to find the air warm and muggy. You hear the twittering of Amazonian songbirds, and the croaking of rainforest frogs, as well as the calming whoosh of an artificial waterfall. It's quite nice inside, despite the humidity.
You join a crowd surrounding a docile-looking but massive mottled-green snake, as well as an excitable twenty-year old guy in the green-polo-and-khakis of the zoo staff in the middle of a lecture.
"So this is Bobby, our Eunectes panphagous, or great anaconda here at the zoo. He's very docile, but if you get him riled up he's got quite the appetite! As it happens, you guys are in luck, he hasn't eaten in over a month - it usually takes him about a month to digest a human, but he can go for half a year without food if he needs to. He's also a really good swimmer. In fact," the staff member gestures to the pool of water behind him, "there are two more anacondas in the habitat behind me. You can see their heads poke up for air once in a while, if you look closely!"
One of the girls in the crowd, close to the pool, takes a step back. The guide notices and laughs. "Oh don't worry, the other two were fed recently, they won't hurt you. But," he said, petting the head of 'Bobby', "this guy's getting pretty hungry - and horny. Anyone want to volunteer to get close and personal with a big ol' snake?"