the synthesist
by kim tingley
compound called a luciferin reacts with oxygen and is then catalyzed by an enzyme called luciferase, the resulting energy appears as light. But scientists don’t believe bioluminescence evolved for the purpose of illumination. Instead, it likely arose soon after oxygen did—some 2.5 billion years ago—as a way of helping early organisms prevent this increasingly ubiquitous (and toxic-in-high-doses) element from damaging their cells. Bioluminescence converts oxygen into light energy hyperefficiently; indeed, says Michael Latz, a marine biologist at the Scripps Institution of Oceanography, “it is actually the most potent antioxidant that we know about.” The more researchers learn about what triggers bioluminescence, the more they can use it as a tool to study systems previously invisible to us. Scientists have already genetically engineered harmless bioluminescence into plants and animals, including the cultured cells of humans, in an attempt to observe the regulation of certain genes and the activity of proteins. Because dinoflagellates—plankton that are the most common source of bioluminescence at the ocean’s surface—glow with a brightness directly proportional to their level of agitation, researchers have been able to use them to illuminate the complex forces at work inside a single wave, as well as to highlight the fluid dynamics that allow dolphins to shoot through the water with such remarkable speed. Bioluminescence also offers new ways to observe the health of ecosystems. In the Caribbean, Latz is studying bays that glow year-round, thanks to an abundance of dinoflagellates. “The bioluminescence is a sentinel—we can use it as an indicator of environmental quality,” he n astonishing variety of living things says. Storms can disturb a bay’s dinoflagellates and cause its glow to generate light: bacteria, beetles, flies, fish, krill, millipedes, comb jellies, worms, squid, shrimp. For dim until things settle back down. By tracking shifts in brightness, reasons we don’t fully understand, most of these Latz’s team can measure the bays’ resilience in an era when climate creatures live in the ocean. Below 3,000 feet, where change is increasing the frequency and intensity of coastal storms. The marine biologist Edith Widder, of the Ocean Research and Consunbeams never reach, more than 80 percent of swimmers and floaters flash or glow in some man- servation Association, has used bioluminescent bacteria to map the distribution of heavy metals and fertilizers in the Indian River Lagoon, ner. All fish that make their homes in these rayless one of Florida’s most troubled waterways. ocean zones have eyes, presumably for the sole purpose of viewing More than ever, it seems, scientists are able to see new evidence of such displays, some of which appear as ghostly blue-green beacons, others of which flash like Christmas strands that festoon rippling, ecological upsets like man-made climate change and hazardous waste in the form of glaring, real-time warnings. But are we willing to dim pulsating forms of alien life. some of our own lights in deference to the natural lamps we’re beginHowever they display it, on land or in the sea, all bioluminescent ning to turn to for these environmental alerts? species use their light strategically. In their recently Now that humans have illuminated so much of published primer, Bioluminescence, J. Woodland For more on the intersection of the world, the darkness that makes bioluminescent Hastings and Thérèse Wilson write that fireflies blink science, culture, and the environsignals so visible—and so valuable to the species that to attract a mate. Anglerfish dangle a pouch of glowment, visit onearth.org/scitech generate them—is disappearing. Indeed, says Latz, ing bacteria above their mouths to lure prey. Blind artificial nighttime glare is already interfering with the observability millipedes shine to remind predators that they’re poisonous. Some of the bays he studies, threatening to overpower the radiance that fish, shrimp, and squid illuminate their bellies to match the intensity of whatever moonlight or sunlight is filtering down from above, effec- broadcasts how they are faring. “I consider them ecological wonders tively camouflaging themselves from any creatures swimming below. that need to be preserved,” he says. He’s hoping for a brighter fuUpon encountering the spectacle of oceans shimmering with ture—of deeper darkness and more easily visible bioluminescence. bioluminescent plankton, René Descartes, the seventeenth-century “The darker it is, the better you can see it.” French philosopher, thought he was witnessing combustion, and posited that sea-salt crystals were flammable. In fact, biolumines- Kim Tingley writes the Working Hypothesis column for onearth.org. Her work cence is created not by heat but by a chemical reaction. When a also appears frequently in the New York Times Magazine.
got a light, buddy?
A 2 4 onearth
fall 2013
illustration by jesse lefkowitz
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