Glowing can get you dates, hide you from a predator or snare you prey — depending on which species you hang out with.
Lightning bugs use their glowing behinds as love lights; small sharks use glow as camouflage; fish species can make their appearance mirror-like; mushrooms may use moonglow to spread their spores and conquer the world.
"Creatures of Light: Nature's Bioluminescence" is running at Chicago's Field Museum through Jan. 5, 2014. The exhibit was organized by the American Museum of Natural History in New York, in collaboration with the Field Museum and the Canadian Museum of Nature in Ottawa.
The Field's exhibit curator, Leo Smith, said bioluminescence is widely dispersed through flora, fauna and fungi.
Living things use a slight variant on one exotic protein, luciferin, one exotic enzyme, luciferase, along with the common-as-dirt biochemical adenosine triphosphate and oxygen in the chemical reaction.
"It's a strategy many species have in their toolkit," Smith said.
Thus, Field has glowworms from New Zealand's Waitomo caves, fish that light up the darkest and deepest of seas and mushrooms that thrive on decayed wood in East Coast woodlands.
He's interested in how dissimilar species evolve apart from each other, yet use very similar strategies.
Smith, who has a Ph.D. from Columbia University, is particularly interested in venomous fish. Venom and bioluminescence have some similarities in how organisms apply them, he said.
The exhibit begins with the forests of North America and bioluminescent mushrooms.
Smith said Illinois might not have any such glow-in-the dark mushrooms to hunt for, but they can be found in the eastern part of the country.
"They grow on decaying wood," he said. "That stuff underground makes the mushroom the most complicated of the bioluminescent organisms."
While it's clear fireflies are hooking up based on chemical messages, mushrooms are more mysterious.
Their glow might make them attractive to species that would eat them and disperse their spores, Smith said.
The next part of the exhibit, "A Summer's Night," is modeled on a meadow in the eastern U.S. Large-scale models show details of female and male fireflies. Then you can communicate with electronic fireflies by flashing lights in the same pattern.
"Some people make comparisons to Morse code. Different patterns of flashes keep different species from accidentally mating with each other in the forest," Smith said.
The world darkens as you proceed through the exhibit.
"You keep going deeper, from mountains to caves to lagoons to deep seas," Smith said.
"A Mysterious Cave" looks at New Zealand's Waitomo cave system and its "fishing lines" strung by glowworms, which are bioluminescent larval gnats. The sticky lines trap dinner.
The cave also has millipede species and the railroad worm, a larval beetle with red "headlights" and yellowish-green "windows" on its sides, according to the museum's website.
In "Deep Ocean," visitors learn that the ability to generate light is much more common for creatures in vast waters.
Below 2,300 feet, perhaps 90 percent of creatures are bioluminescent, Smith said.
But the exhibit warns that pollution, overfishing and climate change could cause a loss of many species.
Large-scale models show deep-sea creatures like the female anglerfish. She has a modified fin spine topped with a lure that pulses with bacterial light to attract prey — a built-in fishing rod.
A vampire squid can wave bioluminescent arm tips to confuse attackers long enough to get away.
"Most of the time in the deep sea, organisms glow to attract, either their own species or their prey. Some sharks use it for camouflage. Others make themselves hard to spot from beneath by trying to maintain a certain level of light, lighting up their bellies to match the light source above," Smith said.
A companion iPad app is available for free download in the iTunes store, Smith said.
"Kids like iPads to see big models to focus on this fish section or bird section," he said. "There's enough information on the app to go deeper and play a few games."
If you go
What: "Creatures of Light: Nature's Bioluminescence"
When: Through Jan. 5, 2014
Where: The Field Museum, 1400 S. Lake Shore Drive, Chicago
Museum hours: 9 a.m. to 5 p.m. daily (closed Christmas day)
Tickets: Prices depend on which package of exhibits you purchase
More information: 312-922-9410; fieldmuseum.org