In the 17th-century, although the English had the opportunity, they chose not to make land on Cuba. They bypassed the island because they saw flickering lights that they believed were the campfires of the Spanish. Those lights were actually fireflies. The humble, yet brilliant firefly probably changed the course of history, which isn't surprising since it has long captured our imagination:
- In the Philippines, one story tells that they are the remnants of a star on the forehead of the Princess Alitaptap, who was sent from the heavens. The star was shattered when she was killed. The pieces rose as fireflies following her death.
- Another Filipino story proposes that fireflies are the descendants of a vain young man who offended a fairy. She turned him into a bug and told him that he would remain that way until he could find another more beautiful than her. So he searches each night, carrying a torch to illuminate his way.
- Still another Filipino legend tells that fireflies got their lights at the suggestion of the sampaguita bush: They took refuge from the dark in the leaves of the bush, and told it they were hiding from the fruit bat, who would only cease its pursuit when the moon was full. The sampaguita bush advised them to carry torches and travel in groups to emulate the moon and blind the fruit bat.
- In Japan, fireflies are the tears shed by a beautiful moon princess who had to return to the sky on her twentieth birthday and leave behind those she loved.
- And among the Cherokee, there a legend about the stars descending from the heavens to help find a lost child. They took the form of fireflies to guide searchers to her location.
Bioluminescence, the ability of some organisms to produce their own light by chemical reaction, has fascinated humans for centuries. So called "living light," has been recognized in folklore, superstition, and the arts. For example, sailors once thought the bioluminescent wake from the bows of their ships were evidence of Poseidon's hand, glowing fungi have been thought to be lost spirits or fairies, and Tennyson has likened the Pleiades to a swarm of fireflies. In fact, bioluminescence is one of the oldest fields of study. Aristotle was the first to record in detail the light he observed in sea creatures, noting that the light was cold as compared to the light cast by a fire or a candle.
Creatures of Light: Nature's Bioluminescence is an exhibit opening this Saturday—March 31st—at the American Museum of Natural History that looks to continue Aristotle's initial forays. Fireflies are not the only organisms to glow. They're just the ones that we've most likely come in contact with. And it's a starting point for Creatures of Light that draws visitors in with something familiar, reminding them of childhood summer pursuits and explaining some of the mystery of the phenomenon. After passing under a giant glowing mushroom—and feeling a bit like you've fallen down the rabbit hole—visitors get to know nature's own flashlight.
From there, the exhibit takes visitors across the tree of life through different environments—from dinoflagellates in Mosquito Bay to glowworms in the Waitomo cave system to corals in the Bloody Bay Wall in the Cayman Islands—to explore the evolution of bioluminescence in a variety of species. Each environment becomes its own world. For example, you can stick your head into a cavern and look up at the glowworms dangling from the ceiling. Or scatter the dinoflagellates as you "wade" in Mosquito Bay—where the light emitted by these protists was once so bright that tourists could read in the evening by the water. (When the canal was widened for development prospects, the light disappeared.) You'll also travel to the depth of the ocean to visit briefly with anglerfish, ponyfish, jellyfish, and flashlight fish. The exhibit is also careful to note the difference between bioluminescence, which is an internal chemical reaction, and fluorescence, which is triggered by an external factor, such as a particular wavelength of light. For example, the corals in the Bloody Bay can appear as red, green, and orange depending on the wavelength of light they're exposed to, which greatly changes the appearance of the coral, fishes, and anemone that call this environment their home.
All of that aside, the exhibit is also a chance to confront legends:
Panellus stipticus, the bitter oyster mushroom, grows in the forests of the eastern United States. The light it generates was believed by North American settlers to be supernatural—fairy lights that would lead you to your doom if you followed them. The sense of doom associated with the fungus is likely rooted in the fact its often found on decaying wood, hardly making it a welcoming context. The light is likely an evolutionary defense system that warns potential predators that there's no meal to be had with these mushrooms.
Dinoflagellates are single-celled marine plankton that are found throughout the world. They give water its sparkle under the moonlight. And they're the basis for reports of "burning" seas by sailors who caught sight of their mysterious light in the water. They're triggered by movement, and the light is actually part of their defense system: it will startle predators or attract larger predators that will find a meal in their would-be attacker. (It's the circle of life, folks.) These tiny creatures were likely also the basis for the Poseidon's Wheel legend: the luminescent wake from the bows of ships resemble the spokes of a wheel. It was apparently a short leap for sailors to associate those spoke with Poseidon's chariot.
And to meet the strange citizens of the deep:
The anglerfish is equipped with her own luminescent lure. The depths of the ocean hides her true nature, and inquisitive fish soon find themselves wishing they'd stayed away from the light.
The vampire squid is so named for its cape-like arms. Because this squid lives in the depths of the ocean, it doesn't have the camouflage as a defense technique. Instead, it uses bioluminescence to frighten predators away.
All organisms respond similarly to illumination: even as we're drawn to light, it can also be a warning. In most cases, scientists believe bioluminescence has a communicative function—which is also what we're doing as we illuminate our world. Light, for many, means power in more than one sense of the word, especially when you consider that it's only recently that light has come to most of the world. Prior to the mid-1800s, people in small towns and villages were used to darkness following sunset that was broken only by the odd candle or lantern. But a relationship to light is clearly not unique to our species. Bioluminescence has evolved numerous times as the chemistry to produce this light varies between organisms—and we've only just scratched the surface in understanding its purpose and potential applications. Let there be light, indeed.
Creatures of Light opens on March 31st, 2012 at the American Museum of Natural History.