by Edith Widder
This new lure, dubbed the electronic jellyfish, or e-jelly for short, was fashioned as a ring of blue LEDs on a circuit board that was then cast in clear epoxy to make it waterproof. For the mold, we used a round plastic food container, which had a medusa-like shape and appearance—so long as you ignored the impression of the letters across the top of the bell spelling out ZIPLOC.
My goal was to place the EITS at some deep-sea oasis—a biologically rich patch of ocean floor that large predators might be likely to patrol—and leave it there for periods of a day or more to see what might come around. The oasis I selected was one that I had wanted to visit since I first learned about it. Known as the Brine Pool,*4 it’s an underwater lake in the northern Gulf of Mexico. The idea of an underwater lake is an Alice in Wonderland concept that is difficult to get your head around. It’s definitely one of those things you have to see to believe.
Back when dinosaurs roamed the Earth, the Gulf of Mexico looked very different than it does today. It was smaller, with a narrower opening to the ocean. Periodically it would dry out, creating thick layers of salt. Plate tectonics eventually caused the gulf to open up and flood. Sediments then built up on the seafloor. In places where those ancient salt deposits poke through the sediment, the salt dissolves, forming super-salty seawater called brine. Brine is heavier than regular seawater and therefore collects in pools, with distinct shorelines, on the floor of the gulf.
As if that’s not weird enough, in some cases, hydrocarbon deposits co-occur with the brine, resulting in chemosynthetic communities similar to those found around hydrothermal vents, only there is no extreme heat involved, so these are called cold seeps. Life flourishes here in the absence of sunlight because energy-rich compounds like methane, hydrogen sulfide, and ammonium seep up through the seafloor, providing sustenance for organisms like tube worms*5 and giant mussels that manage to subsist on these compounds with the help of symbiotic relationships with chemosynthetic bacteria. One such community around the Brine Pool has the largest accumulation of chemosynthetic mussels found so far in the Gulf of Mexico.
That I was actually going to get to see this fantastic place with my own eyes was thrilling just by itself, but I was also entertaining high hopes for what new discoveries might arise out of the Eye-in-the-Sea rigged with its simulated stoplight-fish illumination system and e-jelly lure. Plus, my collaborators on this adventure, a mix of international experts in optical oceanography and visual ecology, shared my passion for understanding what part light plays in the lives of animals in the ocean. As a bonus, they were a lot of fun to be with at sea.
All told, there were sixteen of us in the science party. Key players included Tammy Frank, who was serving as co–chief scientist with me and studying the visual sensitivities of animals that we captured in the dark; Sönke Johnsen, who had moved on from being my postdoc to a tenure track position at Duke University and who planned to analyze the camouflage strategies of deep-sea bottom dwellers; Justin Marshall, an expat Brit who had moved to Australia and would work with Sönke to study what role polarized light might play in deep-sea visual ecology; and Erika Montague, my graduate student at the time, who was working with me on the Eye-in-the-Sea experiments. Sönke, Erika, and Justin shared a similar slightly twisted sense of humor, and based on past experience, their practical jokes on one another were likely to provide considerable entertainment for the rest of us.*6
The mission plan was to visit four dive sites during the ten-day expedition. The Brine Pool, farthest from our starting point in Panama City, Florida, was last on the schedule. To undertake all the planned experiments and give all six principal investigators opportunities to dive in the submersible, we were scheduled to make three dives a day with the Johnson-Sea-Link rather than the usual two. It was a densely packed, complicated, and optimistic schedule.
A mere eight hours into the mission, the weather turned nasty. The wind was blowing at twenty knots, and predictions were that it was only going to get worse. Rather than waste precious dive time sitting around waiting for it to clear, we decided to reverse the schedule and make the long transit to the Brine Pool, which was about 150 miles southwest of the Mississippi delta, and hope that the weather would clear up (as the reports were predicting) by the time we got there.
We arrived onsite late afternoon the next day and, miraculously, the weather was glorious. The first dive hit the water just after four p.m., with the pilot and me up in the bubble while Erika rode in the rear dive chamber with a subby.*7 To stay on schedule, we needed to get in two dives before midnight. It would be tight. We had half an hour to reach bottom, just below 2,100 feet, an hour to deploy the EITS along with some animal traps, then another half an hour to return. As we descended, I watched eagerly for signs of bioluminescence. The first flashes appeared at around 1,000 feet, at which depth I could still distinguish dim blue light overhead. By 1,200 feet, that blue ceiling had turned charcoal gray before fading to black at 1,800 feet, when the pilot flipped on the sub’s lights.
We continued our descent down past 2,100 feet, where the edge of the Brine Pool loomed into view. The pool had a distinct surface, a consequence of the refractive index difference between its dense salty brine and the much less salty seawater overlaying it. It was a disorienting sight—a lake within a sea, with a conspicuous shoreline covered in giant mussels. These were at least twice as big as any I’d ever seen, and they were packed in so tight, there were a couple hundred per square foot. Their colors were a kaleidoscopic mélange of browns—walnut, rust, peanut—and charcoal grays, with flecks of white from open shells, while the lake was nearly black, grading to a dark mossy aquamarine in the direct splash of the sub’s lights.
As we approached, I saw a hagfish swim down in front of the sub, pass through the surface, and disappear into the lake, only to reappear and swim away. Other, less primitive fish that had tried this apparently hadn’t fared so well in the salty brew, as evidenced by a couple of carcasses floating on top of the lake.*8 I asked the pilot what would happen if we tried to sink into the brine. “We can’t get through—it’s too dense,” he answered and then proceeded to demonstrate by setting the sub down on top of the pool. Bizarrely, his maneuvers on the lake’s surface created slow-motion waves that lapped against the shore. The whole scene had a fantastic, alien spookiness about it.
We cruised over the surface of the pool and then up along the western edge, looking for a good spot to deploy the EITS. Erika and I agreed that the mussel beach*9 that formed a wide ring around the pool looked too lumpy to set the camera on safely, so we ended up picking a spot just outside the mussel bed at the northeast end of the pool. This was our first time deploying the EITS from the submersible, so I was worried it might refuse to slide off the rig that was holding it on the front of the sub. But thanks to the robotic arm and the pilot’s skill, the deployment was flawless.
Until we recovered the camera on a subsequent dive, it was impossible to know what the video was picking up, so I had to guess at the field of view, but we tried to line it up with the mussels in the foreground and the edge of the brine pool in the background. We placed the e-jelly, which was on a cable attached to the camera bottle, on top of the mussels, a few feet in front of the camera next to a net bag full of bait. The goal was to draw as many critters as possible into the camera’s view. We also put the animal traps in the same vicinity, with the hope of seeing how the animals reacted and interacted with them. Then we cruised back across the pool to its southeast corner, where there were large bushes of tube worms. We placed the other two traps there and then, incredibly, it was already time to surface.
Both Erika and I desperately wanted to stay and explore this amazing place, but we mollified ourselves by asking the pilot to turn out the lights during the ascent so we could revel in the spectacular display of bioluminescence. It was breathtaking. We could stimulate it either mechanically, by bumping into it, or photically, by exposing it to a brief flash of light
from our flashlights or camera strobes. Anywhere we pointed our flashlights, we would see fragile filigrees of fluff light up and then fade away. And if we used the camera strobe, the effect was even more remarkable, with whole galaxies of luminescence flashing back at us in unison from all around the sub.*10
We left the camera down overnight. First thing the following morning, I went to retrieve it. Tammy rode up front and I was in the back, operating a spectrometer that we were using to measure the penetration of downwelling sunlight into the depths. It was a bulky piece of gear for the small confines of the dive chamber, leaving little room for me and the subby. As we descended, I made a series of measurements that beautifully charted the narrowing spectrum of light characteristic of the deep ocean.
Having stored the last of the spectra on the computer, I was trying to rearrange the gear to give myself enough room to stretch my legs when Tammy yelled into the headset, “Look at that!” I checked the video monitor that showed the camera feed from the front of the sub. Filling the screen was a giant sixgill shark, and it was swimming right past the Eye-in-the-Sea. The word giant felt like an understatement. The pilot shone the scaling lasers*11 on it and estimated it was almost fifteen feet long. Since the EITS was still in record mode, I had every reason to believe we might have video of this goliath, hopefully before the submersible arrived on the scene. I couldn’t wait to get it back on deck and see what we had recorded.
We had nothing. Not a single frame. It was a crushing disappointment. We consoled ourselves that at least it hadn’t flooded. Erika and I immediately went over the system piece by piece but could find nothing mechanically wrong and eventually concluded that one of us (who shall remain nameless) had inadvertently loaded an old configuration file. Sönke had once said that we all lose at least ten points of IQ at sea,*12 and this event supported his theory. We immediately instituted a policy of both of us inspecting the setup for each deployment and, after triple-checking that we had the right configuration file loaded this time, we had the camera ready to go down again right after lunch. We had programmed it to collect video through to the next morning, when we would make our last dive at the Brine Pool.
This final dive had Justin in the front and one of the grad students in the back. They reported no sign of the sixgill shark, which was disappointing, but they recovered the camera without incident and were back on deck with the EITS before ten a.m. Erika and I immediately checked the camera and were relieved to see that this time we had video, but there was no time to look at it because we had to quickly download the memory and prep the camera for the next deployment, at a place called Green Canyon.
This time, Sönke sat in the front while I worked the spectrometer in back. It was one of the few times in my life that I was anxious for a dive to be over. After so many years of trying to peer into the darkness, I had reason to believe we might finally have succeeded, and I wanted to get back and find out what was there. We deployed the camera near some tube worms and then hovered a hundred feet above it to try to see the e-jelly come on. We had programmed it to start displaying immediately this time and, sure enough, it came on and was readily visible from that distance. I had real cause to hope that it might draw in visual predators from a long way off.
As soon as we were back on the ship, I adjourned to the lab to review the Brine Pool video. The good news was that everything seemed to be in focus. The bad news was that neither the e-jelly nor the bait bag was in the field of view. It looked as if the tripod might have settled back into the mud, tilting the camera up so that both the bag and the e-jelly were just below the bottom of the frame.
Nonetheless, I could still see some of the mussels and the edge of the brine pool. Even better, I could see fish and giant isopods swimming around, seemingly oblivious to the camera lights. To almost anyone else, I’m sure it looked like a pretty uninteresting scene, but I was on the edge of my chair, my eyes riveted to the monitor. I was finally gazing into this other world, and I was invisible to its inhabitants. That meant that at any moment I might see something no one had ever seen before. For me, this was akin to discovering the entrance to King Tut’s tomb, and although I didn’t know it at that moment, I was about to uncover the golden sarcophagus.
For this first deployment of the EITS, I had delayed activating the e-jelly until four hours had passed so I could have a good, long look at undisturbed behavior. I had gotten to the section of the video where the e-jelly was activated when, just eighty-six seconds after it came on, the video screen filled with what looked like an enormous squid. I bolted out of my seat and whooped so loud that people came running from all over the ship to see what I was shouting about. We all watched it over and over again.
It was a strange-looking squid. The oddest thing about it was its tentacles, which were short and muscular instead of long, thin, and stretchy. The squid looked to be attacking the e-jelly just below the bottom of the frame. As it withdrew from the failed attack, apparently by flapping its fins, which we could see only partially at the top edge of the frame, it flexed one of its tentacles out to the side. The appendage was so thick and short, it looked like one of the arms, except that it was lighter-colored, lacked suckers, and was two-thirds the length.
One of the great blessings and curses of modern oceanography is that we now have email at sea. That access meant that, instead of having to wait to return to shore, I could send the video clip to squid experts at the Smithsonian, who got back to me almost immediately with the amazing pronouncement that this squid was completely new to science. It wasn’t just a new species or a new genus, but possibly an entirely new family!*13 The full significance of that took a while to sink in, but I was sure of one thing: I could not have asked for a better proof of concept. The discovery of a new animal alone would have been enough to declare this expedition a massive success, but we weren’t done yet.
As we all sat around reviewing the video of the mystery squid, we were bemoaning the fact that the e-jelly and bait bag weren’t in the field of view. I wanted to be able to definitively say that the squid had been attracted by the e-jelly, and I also needed a scale reference to properly size the squid. I guessed it was about six feet long, but that was based on how far away I estimated the e-jelly was from the camera. The only solution in the short term seemed to be to make every effort to place the e-jelly squarely in the camera’s field of view for each of the remaining deployments. However, on the next deployment we faced the same problem: The e-jelly and bait were out of sight, just below the bottom of the frame.
We all agreed that the solution was to attach some kind of extension to the camera frame that would hold the e-jelly at a fixed distance from the camera. Because of the very tight clearance during launch and recovery between the EITS, loaded on the front of the JSL, and the aft end of the ship, it would need to be something that we could fold down after the EITS was on the bottom and then fold up for recovery. I had no doubt the engineers back at Harbor Branch would find a way, but that would have to wait until the next expedition.
At least that was my thinking as I drifted off to sleep that night, but the following morning a new option was presented to me by Justin and Erika, who had stayed up all night fashioning a Rube Goldberg solution. They had found an aluminum ladder that they convinced the captain to let them cut up. It was now attached to the bottom crossbar on the EITS frame with ring clamps so it could be rotated from horizontal to vertical, where it locked into place with a spring-mounted hook. The e-jelly itself was attached to a separate short section of the ladder, canted in such a way that it was positioned in the bottom center of the frame. It looked sketchy, but it was actually a pretty solid piece of engineering, as was proven on its first deployment, when it worked exactly as advertised. The big moment came after the EITS was placed on the bottom and the sub’s robotic arm reached out to release the spring holding the ladder up. The frame rotated down so majestically, when I saw the video of the deployment, I wanted to score it wit
h Strauss’s “Sunrise” fanfare, used in 2001: A Space Odyssey.*14
We put it down for only a few hours on that first deployment, just to make sure it worked. When we looked at the video, we decided the ladder was a little too high in the field of view and too reflective, so we adjusted its position and spray-painted the whole thing black. The next time we deployed the EITS, we not only attached a bait bag next to the e-jelly but we tie-wrapped fish heads to the ladder rungs. It was a deep-sea sushi platter that we hoped would lure in some exciting guests. Two days later, when we got it back on deck, it was evident that we had indeed attracted visitors to the buffet, because the bait bag was missing and there were scratch marks on the paint all around the fish heads.
This time there was a crowd around the video monitor as I reviewed the recording, and I wasn’t the only one whooping. There were hake fish and giant isopods*15 munching on the bait. A rosefish, which we dubbed the “peekaboo fish,” kept coming in to look at the e-jelly every time it came on, and, for the grand finale, another giant sixgill shark loomed up out of the darkness, used its head to shove a giant isopod out of the way, and then opened wide to start chowing down on the bait. We posted these videos on the web page that NOAA had set up to highlight our expedition and later learned that they had created a lot of excitement.
For the proposal to NOAA, I had come up with the expedition name Deep Scope to emphasize that we were going to be attempting a different way of exploring, using new technological eyes to peer into the depths and to provide a novel perspective that focused on what the eyes of animals were adapted to see.*16 Deep Scope 2004 was so successful that NOAA funded our team to pursue this line of inquiry for subsequent missions in 2005, 2007, and 2009, and the Eye-in-the-Sea played a significant role in each of these expeditions. It seemed as if every EITS mission produced new revelations about the nature of light and life on the deep seafloor, but one of the most thrilling for me was the 2007 expedition to the Bahamas where I finally managed to talk to the animals.
