Bioluminescence: Light Is Much Better, Down Where It’s Wetter- page 5 | Science | Smithsonian
Jellyfish glow with the flow in the Gulf of Maine and the Weddell Sea. (David Shale / NPL/ Minden Pictures / Ingo Arndt / Minden Pictures)

Bioluminescence: Light Is Much Better, Down Where It’s Wetter

From tracking a giant squid to decoding jellyfish alarms in the Gulf, a depth-defying scientist plunges under the sea

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(Continued from page 4)

Once she found a way to measure undersea light, she started trying to distinguish more precisely among the myriad lightmakers. On her increasingly frequent deep-water excursions, Widder had begun to watch for themes in the strobelike spectacles. Different species, it seemed, had distinct light signatures. Some creatures flashed; others pulsated. Siphonophores looked like long whips of light; comb jellies resembled exploding suns.

“To most people it looks like random flashing and chaos,” says Robison, who became one of Widder’s early mentors. “But Edie saw patterns. Edie saw that there is a sense to the kind of signals that the animals are using, and the communications that take place down there. That was a breakthrough.”

What if she could identify animals just by the shape and duration of their glow circles? She could then conduct a bioluminescent census. Widder developed a database of common light codes that she’d learned to recognize. Then she mounted a three-foot-wide mesh screen on the front of a slow-moving submarine. When animals struck the mesh, they blasted their bioluminescence. A video camera recorded the flares, and a computer image-analysis program teased out the animals’ identity and location. Widder was gathering the sort of basic information that land-based biologists take for granted, such as whether, even in the ocean, certain species are territorial. The camera was also a window into the nightly swarming of deep-sea creatures toward the nutrient-rich surface—the “vertical migration” that is considered the largest animal migration pattern on the planet. “The whole water column reorganizes itself at dusk and dawn, and that’s when a lot of predation happens,” she says. “Do certain animals hang back and vertically migrate at different times of day? How do you sort that out?”

As useful as these inventions proved, some of Widder’s most stunning discoveries came to light just because she was hanging out in the right place at the right time, as her mother told her to do. Often that was about 2,500 feet underwater. On a submersible in the Gulf of Maine, Widder trapped a foot-long red octopus and brought it to the surface. It was a well-known species, but Widder and a graduate student were the first to examine it in the dark. (“People just don’t look,” she sighs.) Flipping off the lights in their lab, they were astonished to see that where suckers are found on other octopuses, rows of gleaming light organs instead studded the arms. Perhaps run-of-the-mill suckers were not useful to an open-ocean resident with few surfaces to cling to, and carnival­esque foot lights, likely used as a “come hither” for the animal’s next meal, were a better bet. “It was evolution caught in the act,” Widder says.

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Even though the twinkling lingo of light is more complicated and far subtler than she initially imagined, Widder never stopped wanting to speak it. In the mid-1990s, she envisioned a camera system that would operate on far-red light, which humans can see but fish cannot. Anchored to the seafloor and inconspicuous, the camera would allow her to record bioluminescence as it naturally occurs. Widder—ever the gearhead—sketched out the camera design herself. She named it the Eye-in-the-Sea.

She lured her luminous subjects to the camera with a circle of 16 blue LED lights programmed to flash in a suite of patterns. This so-called e-Jelly is modeled on the panic response of the atolla jellyfish, whose “burglar alarm” display can be seen from 300 feet away underwater. The alarm is a kind of kaleidoscopic scream that the assaulted jellyfish uses to hail an even bigger animal to come and eat its predator.

The Eye-in-the-Sea and e-Jelly were deployed in the northern Gulf of Mexico in 2004. Widder placed them on the edge of an eerie undersea oasis called a brine pool, where methane gas boils up and fish sometimes perish from the excess salt. The camera secure on the bottom, the e-Jelly launched into its choreographed histrionics. Just 86 seconds later, a squid lurched into view. The six-foot-long visitor was completely new to science. When deployed in the Monterey Canyon, Widder’s Eye-in-the-Sea captured stunning footage of giant six-gill sharks rooting in the sand, possibly for pill bugs, a never-before-seen foraging behavior that might explain how they survive in a desolate environment. And in the Bahamas at 2,000 feet, something in the blackness flashed back at the e-Jelly, emitting trails of bright dots. Each time the jelly beckoned, the mystery creature sparkled a response. “I have no idea what we were saying,” she admits, “but I think it was something sexy.” At long last, Widder was engaged in light conversation, most likely with a deep-sea shrimp.

A sensational highlight came last summer in the Ogasawara Islands, about 600 miles south of Japan, when Widder, the e-Jelly and a floating version of the Eye-in-the-Sea called the Medusa joined an effort to film the elusive giant squid in its natural habitat for the first time. Other missions had failed, although one captured footage of a dying giant at the surface. Widder was nervous to use her lure and camera in the midwater, where the devices dangled from a 700-meter cable instead of resting securely on the bottom. But during the second, 30-hour-long deployment, the Medusa glimpsed the squid. “I must have said ‘Oh my God’ 20 times, and I’m an agnostic,” she says of first seeing the footage. The animals can supposedly grow to be over 60 feet long. “It was too big to see the whole thing. The arms came in and touched the e-Jelly. It slid its suckers over the bait.”

She caught more than 40 seconds of footage and a total of five encounters. At one point, the squid “wrapped itself around the Medusa, with its mouth right up near the lens,” Widder says. The huge squid didn’t want the puny little e-Jelly; rather, it was hoping to eat the creature that was presumably bullying it. Another scientist on the same voyage subsequently filmed a giant squid from the submarine, and that footage, along with Widder’s, made headlines. It was e-Jelly’s pulsating light that roused the giant in the first place, making history. “Bioluminescence,” Widder says, “was the key.”

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About Abigail Tucker

A frequent contributor to Smithsonian, Abigail Tucker is writing a book about the house cat.

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