by Edith Widder
Given my experience with U.S. Marines during David’s tenure as a hospital corpsman, I had more than a passing familiarity with use of the F-bomb. For Marines, it’s a form of punctuation often employed where most people might insert a hyphen or an exclamation point. For the captain of the Kane, its use attained new, previously unimagined heights. In retrospect, I wish I had kept count, but when he started, it never occurred to me that we might be entering Guinness World Records territory.
The expedition was not fun. Besides rough seas and bad food, the captain was a jerk*7 who made it abundantly clear he was not effing pleased by my steadfast refusal to stop by his cabin to see his collection of memorabilia—all supposedly engraved with his life’s philosophy: SHIT HAPPENS. Nevertheless, the HIDEX performed well. It satisfied all of the Navy’s requirements. We were issued a patent and it was officially deemed the U.S. Navy standard for measuring bioluminescence in the world’s oceans. More important, I was able to kick my Tums and Maalox addictions.
As for the Soviets’ part in the story, they figure into two interesting addenda. The first was a scientific paper that came out a year later in the journal Oceanology, in which much Soviet science research was published. The publication by several Soviet scientists touted a whole new kind of bathyphotometer, one that on the outside was a dead ringer for the HIDEX but on the inside bore no resemblance—apparently despite their best efforts, the only real intel they gathered was those photos they got the first night.
The second occurred at an International Symposium for Bioluminescence and Chemiluminescence that happened after the fall of the Soviet Union. I was sitting at lunch with a British colleague when several former Soviet scientists sat down opposite us. My colleague knew them and introduced me as the inventor of the HIDEX-BP. The gentleman opposite me did a classic jaw drop and then blurted out, “But I thought you were…” before he stopped himself. I’m not sure what he was going to say. A man? Older? Dead? There’s no way to know for sure, but based on the expression on his face, it seemed to matter to him, which I decided to take as a compliment for the HIDEX, if not necessarily for me.
For the Navy, the HIDEX-BP provided the numbers they needed for calculating something called nighttime water-leaving radiance. If a submarine was moving through a particular ocean at night, at a certain speed and depth, how much bioluminescence would it stimulate, and was it detectable at the surface?
For me, the HIDEX opened up a new perspective on the nature of the bioluminescent minefield. The most surprising discovery it produced was the existence of thin layers of intense bioluminescence, less than twenty inches thick. Their presence had obvious strategic importance to the Navy. But from the perspective of understanding marine ecology, it was part of what at that time was becoming a revolution in thinking about the distribution of life in the ocean.
Because net sampling provides a jumbled mass of life, for a long time there was a widely held impression that the ocean is like a soup, with everything mixed together. But there were a number of new sampling technologies, some acoustic, some optical, some mechanical, that were allowing scientists to look at life in the ocean on a finer and finer scale.
The closer we looked, the more we found what was called patchiness. Animals weren’t evenly distributed, but were found in clumps. For example, when I got to dive a submersible with a SPLAT screen through those bioluminescent thin layers, I discovered that they were composed of a dense aggregation of bioluminescent copepods. These copepods (Metridia lucens) were apparently feeding on a layer of marine snow that had accumulated between two water masses of different density.
Understanding the nature and causes of patchiness is one of the grand challenges in oceanographic ecology. It takes a lot of energy to hunt, which means food must be sufficiently plentiful that more calories are consumed than lost. The fact that calculations indicate many predators can’t be sustained by the average concentration of their prey in the ocean suggests that those predators must have some means of finding and exploiting dense patches of prey. Could bioluminescence be a means to that end?
There is some evidence that southern elephant seals exploit bioluminescence to locate nourishment. As the name implies, this is the heftiest of all seals and the largest marine mammal that isn’t a whale, so the species needs a great deal of food. To fill their stomachs, elephant seals spend about ten months a year at sea, diving continuously, day and night, sometimes going nearly five thousand feet deep (about four Empire State Buildings) to forage.
Seals don’t echolocate, but they do have beautiful big brown eyes that are more sensitive than human eyes, and among seals, elephant seals have the most sensitive eyes of all. Since their primary prey are lanternfish and squid, there are two schools of thought. The first is that the seals are homing in on light emissions of their prey, and the second is that they are seeing their prey by the bioluminescence that the fish and squid stimulate as they swim through the bioluminescent minefield of planktonic luminescence. Since foraging forays of elephant seals target the boundaries between water masses, which also tend to be zones of high bioluminescence potential, the minefield scenario seems more likely to me, especially since it doesn’t depend on incessant maladaptive spontaneous emissions by the prey.
If you want to know what it’s like to swim through a minefield of living light, you can find out by visiting a bioluminescent bay. There are several in Puerto Rico. The boat that carries tourists out onto the bay startles fish that dart away in all directions, creating shimmering thin contrails as the vessel itself generates a billowing wake of neon-blue froth.
When the vessel stops, dangle your legs over the side and you will be immediately rewarded with shimmering sequined boots—a scintillating aura that surrounds your limbs, enticing you to kick more and more vigorously until you are gleefully splashing like a toddler in the bathtub, creating a watery eruption of brilliant sapphire.
If you are lucky enough to be some place where swimming is allowed, then you can go ahead and dive in.*8 As you swim, you will be enveloped in a twinkling halo of glittering stardust. Wiggle your fingers in front of your face and watch sparks fly off your fingertips. It’ll feel like you have been magically granted superpowers. You have! Life surrounds us and nature is everywhere, but too often invisible to our eyes. Here, the hidden energy of life is revealed and the response is universal—a heady fusion of joy and awe.
Skip Notes
*1 A skill that allows them to track game in blowing snow, through slush, and over hardpack.
*2 According to the Scientist’s Guide for How to Win Friends and Influence People, you should take every opportunity to point out that Escher’s title is incorrect and it should be renamed Delphinus delphis in Bioluminescent Sea.
*3 An example of such a transition between different kinds of flow can be seen in smoke rising from a cigarette that starts out smooth and laminar, where the layers don’t mix, and then becomes turbulent and chaotic…so it can insinuate itself into every fiber of your clothing.
*4 Pilots call this a kneeboard.
*5 For a more accurate view of the true nature of life as a marine biologist, see Milton Love’s classic rant “So You Want to Be a Marine Biologist?” (Science Creative Quarterly, September 28, 2007).
*6 Wikipedia, s.v. “Six Phases of a Big Project,” en.wikipedia.org/wiki/Six_phases_of_a_big_project.
*7 He was not a U.S. Navy captain, but part of the civilian service that the Navy employs to man its oceanographic survey vessels.
*8 As long as you aren’t wearing sunscreen.
PART II
TO KNOW THE DARK
To go in the dark with a light is to know the light.
To know the dark, go dark. Go without sight,
and find that the dark, too, blooms and sings,
and is traveled by dark feet and dark wings.
—Wendell Berry, “To Know the Dark”
Chapter 8
GLORIOUS PUZZLES
It was a gulper eel. I’d never seen one alive before, but there was no mistaking that long, skinny, scaleless body and the enormous toothless mouth with jawbones nearly a quarter the length of the fish. It was swimming fast, with a snakelike undulation that kept it just ahead of the submersible. But it couldn’t sustain the sprint, and after less than a minute it fell back and then suddenly stopped swimming. The sub pilot, Phil Santos, began maneuvering the sub to keep the fish in front of us as I adjusted the pan and tilt on the external camera, trying to get the gulper into its field of view. I looked down at the controls for a second, and when I looked up I couldn’t grasp what I was seeing. Instead of the black fish, I saw a brown balloon on a black string. And then the balloon split open, as if along a seam, and simultaneously shape-shifted and color-morphed back into the form of the black fish before it started swimming again.
“Did you see that?” I yelled to Phil, wondering if my eyes were playing tricks on me. Obviously, he had to have seen it, since he was scope-locked on the fish and now giving chase. We were at the end of our dive. The surface had already called us up, so there wasn’t time to screw around with lining up the perfect shot. I gave up on the pan and tilt controls and grabbed the camcorder out of my satchel. The next time the fish stopped and performed its fantastic metamorphosis, I was filming. It opened its jaws ridiculously wide, and then, as it closed them, the thin brown skin of its gullet, which appeared black when deflated, expanded, creating a brown balloon that inflated even farther as Phil and I stared in utter amazement.
The scientific name for this fish, Eurypharynx pelecanoides, refers to its crazy mouth: the long (eury) pharynx (the membrane-lined cavity behind the nose and mouth) with pelican-like proportions. It is assumed that this extreme adaptation evolved to engulf prey, like a pelican, but nobody knows for sure because no one has ever seen it feed. It’s rare to find these fish in trawl nets and much rarer still to see one from a submersible.
Undoubtedly, the hugely expandable mouth is used for consuming prey, but here was another possible function. “Is that to keep itself from being eaten?” Phil asked. I shrugged. “I guess. I didn’t know they could do that. I don’t know if anybody knew they could do that.” I was speaking into the recording microphone, describing what I saw: “He puffed his jaw out and made himself into this big balloon.” Then the eel did it again, this time on camera, and I hooted with glee. “That’s incredible! There, we got it. Whatever the hell it’s doing—I got it on video! Wow! That was so cool!” Then, in the midst of my exultation, just as it was deflating again, Phil gave the thrusters a kick, jockeying the craft in such a way that the fish slipped into one of the large collection cylinders on the front of the sub, and, before it could swim away, he activated the hydraulic lids, sealing it inside. I shouted, “Oh, man. You got him? Way to go, Phil!” It was an incredible feat—the equivalent of executing a perfect turnaround jump shot in basketball. I couldn’t believe it.
On the audio track, I was still exclaiming, “That is amazing!” as Phil’s deep, Boston-accented voice calmly announced, “Okay, topside, we’re at 2,400 feet. Request permission to leave this depth.” I tried to settle down to business, but my voice was shaking as I spoke into the recorder. “That is a gulper eel—I can’t believe I’m saying it—in DS6.*1 Depth is 2,420 feet and temperature 4.2 degrees Celsius.”*2 Not only had we been able to record its crazy antics on video, but Phil had captured it in a way that would give me an opportunity to study its bioluminescence.
More than anything, I wanted to get that fish out of the sampler and safely into a tank in the dark, because this was the best chance anyone had ever had to study its light-generating abilities. The gulper eel is a prime example of our general ignorance about how animals in the ocean use bioluminescence. It has an elaborate light organ on the end of its absurdly long tail, causing speculation that it might practice yogalike contortions to dangle its trailer light in front of its mouth as a lure. It also has a groove that runs down the length of its body like a racing stripe, which some scientists had speculated might also be bioluminescent, while others doubted it, and no one had a clue what function it might serve. But I was about to get a clue.
* * *
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After we delivered the HIDEX-BP to the Navy in 1989, it was time to move on from my extended postdoc position at UCSB to a real job. I knew I wanted to learn more about how animals use bioluminescence, which meant I needed to observe the light emitters. The options in this arena were limited. Although the use of remotely operated vehicles (ROVs) was on the rise, providing greater entrée to the deep sea, they were no good for the kinds of observations I wanted to make. They were noisy and obtrusive and essentially blind for my purposes, since the only way to see with an ROV is through its cameras, and no cameras at that time were as good as the fully dark-adapted human eye. I needed a submersible, and not just any submersible; I needed one designed for the midwater, like Deep Rover.
At that time, there were fewer than a dozen deep submersible vehicles in active service nationwide. Of these, only five were being used routinely for serious scientific research, and of those, only two were designed for the midwater. Both were owned by Harbor Branch Oceanographic Institute (HBOI), in Fort Pierce, Florida. As luck would have it, in 1989 they were looking to hire an entry-level scientist with submersible experience. I applied and got the job, which allowed me to set up my own laboratory, designated, according to HBOI protocol, as the Bioluminescence Department. That made it sound a bit grander than it was, but it was unquestionably a plum job, most especially because it included access to HBOI’s research ships and its submersibles, the Johnson-Sea-Links (JSLs) I and II.
The subs were named for the partnership of their financier and inventor, respectively. Because of his deep love of the ocean and its mysteries, Seward Johnson, Sr. (half of Johnson & Johnson), had committed part of his personal fortune to the ongoing development of these cutting-edge submersibles after their inventor, Edwin Link, had financed the early phase of their creation out of his own much smaller personal fortune.
Link originally designed the Johnson-Sea-Link as a means of carrying scuba divers into the ocean. The acrylic sphere where the pilot and scientific observer sat was not actually the business end of the sub; it was merely the bus driver’s seat. The passengers in this “bus” sat in a separate compartment behind the sphere, an egg-shaped metal pod known as the dive chamber. The idea was to take the sub down to the limits of scuba diving depth, as much as a thousand feet, with both the sphere and the dive chamber maintained at atmospheric pressure. Once it was on the bottom, the pressure in the dive chamber was increased until it matched the outside pressure, allowing the downward hatch to fall open and the two scuba divers inside to swim out and get to work. It was the equivalent of performing an untethered spacewalk outside a spacecraft, but instead of the one atmosphere of difference between the inside of a spacesuit and the vacuum of space, scuba divers faced a pressure differential of as much as thirty atmospheres (440 pounds per square inch). Once they had exhausted their very limited bottom time, they could climb back into the dive chamber, close the hatch, and begin their decompression during the ascent. At the surface, the dive chamber coupled directly to a shipboard hyperbaric chamber where the divers would complete their decompression, which, for a dive to six hundred feet, with a bottom time of only four minutes, took twenty-seven hours!
Link soon realized that it would be more efficient if the collection of samples could be carried out with remotely operated devices, controlled from the front of the submersible. Over the years, he and his team of engineers developed an awesome array of collection systems: a robotic arm fitted with a variety of tools, including a claw, a benthic scoop, a suction hose, and cable cutters; a suction sampler called the “critter getter” that used a variable-speed pump and a carousel of twelve one-gal
lon Plexiglas buckets; and a much larger version of this same design with twelve three-gallon Plexiglas buckets. Samples collected with the claw could be dropped directly into these buckets, or they could be drawn into them through the suction hose on the robotic arm. And there were eight wastebasket-sized Plexiglas cylinders, called “D” samplers, like the one we used to capture the gulper eel.
* * *
—
Once back on the deck, I made sure that the “D” sampler with the gulper eel in it was carried into the lab before anything else. The fish was still actively swimming, and as I slid the top open, I tried to figure out the best way to transfer it to a tank for observation. At well over a foot long, it was unwieldy, but highly flexible. I decided to scoop it up into a large glass finger bowl. The capture of this rare fish had drawn a small crowd in the wet lab. I lifted it out of the sampler and we all gasped in unison as a vivid neon-blue bolt of light flared along its length. Brilliant even under fluorescent lights, this was unquestionably the brightest, most dazzling bioluminescence I had ever seen.
The eyes of deep-sea predators are exquisitely sensitive—tuned to detect the very dimmest of flashes and often lacking defenses such as eyelids to block out bright light. To those eyes, a flash of that intensity would be devastating, like looking directly at the white-hot center of an electric arc welder with your eyes unshielded. Shape-shifting wasn’t the gulper’s only defense. Blinding an attacker was another option.
