Amazon’s exhibits are outfitted with soft overhead spot lighting that clicks on around 7 p.m. (when the daytime habitat lights go off) and dims to dark by 10. But this isn’t mood lighting. Called "moonlight mode," it simulates the natural nighttime environment, especially for the exhibit’s crepuscular species - those critters most active at dusk and dawn. And twilight time is the right time for many animals to evade predators as they go about their activities. Then again, in the wild, the dwarf caimans would just be heading out to hunt.

Erica Clayton, collection manager for Amazon Rising, says, "We imitate the natural habitat as much as possible with this exhibit. That is why we do not extend the daylight hours [with exhibit lighting] for special events. The animals key into the time of year by day length. Because of the natural lighting through the skylights, there is seasonal variation in day length, but our goal is to keep the light cycle as constant as possible, as this is what you find at the equator."

So the animals feel at home year-round. And for guests, the effect from the cool 80-watt bulbs is soothing and dreamy—if they don’t mind a few reflective eyes following them. It’s also a chance to view animals out and about that you might not see during a day visit.

From the river beach, with the lowest water levels, through the forest in high-water season, back to receding waters, the underwater activity is amazing. Many of the exhibit’s 90 catfish species (representing about one-fifth of the number in the actual Amazon) dart and churn about. The freshwater rays are more active, too, fluttering their disks up the habitat windows.

You’re also more apt to see one or both of the dwarf caimans come out from under the deep cover of the rainy season forest habitat. The crocodilian clan is well-adapted for activity after dark: The large eyeballs of a caiman (or alligator or croc) are packed with light-gathering cells. In addition, the back wall of the eye has a thin coating of special tissue that reflects light, producing sharp images even in low light—a terrific adaptation for a nocturnal hunter. Light that strikes the caiman’s eyes is reflected back as the eerie reddish-whitish glow called eyeshine.

You might also see more activity among the tree frogs and catch the giant monkey frog moving around. And while the cardinal tetras are not more active at night, the huge shoal of them looks like a cloud of blue fireflies in the subdued light.

So take a moonlit walk through Amazon Rising during Jazzin’ at the Shedd. Like the main galleries, Amazon Rising is open until 10 p.m.—time enough for you to really appreciate this special effect.

- Posted by Karen Furnweger, web editor