Chapter 1 Seeing Light is what, exactly? For something that has no mass, it sure carries a lot of existential weight. It is both an energy source and an information carrier. It can be injurious and it can be healing. It is one thing that can manifest as two things--a wave in the future and a particle in the past. In a vacuum, it travels at the maximum speed allowed by the universe, and it does so without ever decaying. It gives up its energy only when it interacts with other particles, like those that make up the visual pigments in our eyes, and it is through these interactions that we interpret the world around us. For most life-forms on Earth, light is the paramount stimulus that makes life as we know it possible. Green plants harness energy from light to synthesize sugar from carbon dioxide and water. In the process, oxygen is generated as a by-product. As magic tricks go, forming food and breathable air from what seems like nothing is hard to beat. Still, it's not especially flashy. Creating dazzling light from food and air, however, is very flashy. That's the magic of bioluminescence. Of course, to appreciate that particular alchemy, you need something equally miraculous: vision. Being able to see provides a huge advantage in the game of life; it is for this evolutionary reason that 95 percent of all animal species on Earth have eyes. These range from microscopic, such as some single-celled algae that have an eye no bigger than one-tenth the diameter of a human hair, to giant squid with an eye the size of your head. The different ways that such disparate eyes see the world reveal much about the biological needs of their owners. In fact, figuring out what different eyes are best adapted to see is such a valuable tool for probing the nature of life that it has become a whole field of study called visual ecology. If you compare the life of a giant squid inhabiting the deep sea with that of microscopic plankton living in sunlit surface waters, the difference in eye size makes sense: a giant eye collects many more photons than a tiny one and is therefore better adapted for living in a dim light environment. But what about another deep-sea inhabitant, the cockeyed squid? Its name derives from its mismatched eyes: the left eye is giant and bulging and directed upward toward the sunlight, while the right eye is smaller, recessed, and aimed downward into the inky depths. This seemingly makes no sense--until you learn that bioluminescent light organs encircle the small eye. While the large eye hunts overhead for dim, distant silhouettes of prey against a dark, lead-gray background, the bottom eye can use its built-in flashlights to illuminate more proximate prey. Clearly, to understand the visual ecology of the largest living space on Earth, one needs to appreciate the nature and function of bioluminescence alongside the nature and function of eyes. It is inevitable that when we try to figure out what different animals see, we relate it to what we can see. That is a major challenge in the deep ocean, though, where our very presence alters the visual environment. It's difficult to envision a place you are unable to observe in its natural state. Our eyes are adapted for a much brighter existence, which means that when we explore darkness, we must bring artificial lights so intense that to visual systems adapted to the deep sea, they are probably as bright as looking directly into the sun. Since it is such a challenge to observe animals in this realm without disturbing them, sometimes the best way to gain insight into their lives is to learn as much as possible about their eyes. The most important questions to ask about eyes are: What information do they accept, and what do they exclude? All eyes act as filters, allowing in only data streams about the outside world that optimize their owner's chances for survival. Anything that doesn't serve that purpose falls under the banner of too much information. Spending time and energy on producing ultraviolet receptors, for example, and processing and interpreting their output is counterproductive if UV light plays no useful role in detecting vital stuff like food, mates, or predators. Thinking about eyes and what they do and don't see is a mind-stretching exercise. We are blind to so many things in our world--some because of biological constraints, and many more because we simply don't know how to look. Environmentalist Rachel Carson once said, "One way to open your eyes to unnoticed beauty is to ask yourself, What if I had never seen this before? What if I knew I would never see it again? " An even better way to achieve heightened visual awareness is to lose sight and then regain it. As Joni Mitchell sang, "Don't it always seem to go, that you don't know what you've got till it's gone?" That Joni Mitchell song, "Big Yellow Taxi," was released my first year in college. I started at Tufts University in the fall of 1969 as a biology major, with the aim of becoming a marine biologist. But before I had completed my first semester, it was clear that goal would be unattainable without medical intervention. During my precollege physical, I mentioned a pain I'd been having down the back of my left leg. Since I was pretty active--a skier and skater in the winter and a water skier in the summer--I figured I must have pulled a muscle. X-rays revealed otherwise: My back was broken. The doctor illustrated the extent of the break by making two fists with his hands, stacking one on top of the other, and then sliding the top one halfway off the bottom one. The slippage was pinching a nerve going down my left leg, causing the intense and persistent pain I felt whenever I sat down. I'm pretty sure I know when I broke it. I spent a lot of my childhood climbing up into and jumping out of trees in our leafy suburban neighborhood just outside Boston. My favorite tree was an old misshapen willow down by the pond near our house. Its trunk ramped up at a forty-five-degree angle away from the water and then branched into two large horizontal limbs, each with thick vertical branches that created separate "rooms" that made it the perfect pirate ship, tree house, or castle. The limbs were about seven feet off the ground: a comfortable jump that I made hundreds of times with ease. But I remember one Sunday, when I was eight or nine years old and dressed for Sunday school in some stupid frilly dress I hated, the jump didn't go as planned. When we came back from church, I couldn't change into my beloved jeans, because we were going someplace fancy later, but I was allowed to be outside until it was time to go, as long as I promised to stay clean. I wandered off to climb my favorite tree, but when I went to jump down, I remembered my promise and landed in a way that protected my dress instead of myself. A searing pain ripped through my back--like nothing I'd felt before. But it didn't last long, and I shrugged it off. Until that college physical, I thought low back pain was something everybody had. I couldn't remember a time without it. By my first semester at Tufts, it was so bad that I couldn't stand for any extended period, and sitting was equally miserable because of the pain in my leg. The only way I could do homework was by lying flat on my back with a pillow under my knees. This was not conducive to good study habits, as I would often fall asleep and bonk myself in the face with whatever tome I was attempting to wade through--a very effective form of negative conditioning. When it became clear I couldn't go on like this, a spinal fusion was scheduled for the beginning of February. According to the Urban Dictionary, "crumping" is a slang medical term indicating that a patient's condition is rapidly worsening. See also: "circling the drain." I crumped; not during the spinal fusion, which went fine, but afterwards, in the recovery room. I went from okay to Oh shit in a New York minute, flipping around in the bed like a fish on a dock while hemorrhaging nearly everywhere. I had a blood disorder called disseminated intravascular coagulation (DIC). The cause is unknown, but it's often associated with major trauma and manifests as overactive clotting factors in the blood, causing clots to form in the small blood vessels of the body, blocking blood flow to vital organs. In extreme cases, the clotting factors and platelets are consumed to such a degree that severe bleeding ensues. The result, in my case, was that I wasn't just bleeding into my surgical sites but also into my lungs, depriving me of air, hence the fish-out-of-water imitation. Two factors conspired to allow me to survive this medical Armageddon. In fact, I was the first person ever to survive it at Mount Auburn Hospital. The first was that my orthopedic surgeon had recently attended an American Medical Association conference on DIC, which allowed him to recognize the symptoms. Usually, a doctor who sees his patient hemorrhaging will administer coagulants to stop the bleeding, but that just leads to more clotting in the small blood vessels and increased likelihood of organ failure. Instead, my surgeon knew to give me the anticoagulant heparin, thereby averting organ failure but greatly exacerbating the bleeding problem. The second lucky break was that the famous Harken "chest team" happened to be at Mount Auburn that day. The chest team's first order of business was to start my heart, which had stopped. Excerpted from Below the Edge of Darkness: A Memoir of Exploring Light and Life in the Deep Sea by Edith Widder, All rights reserved by the original copyright owners. Excerpts are provided for display purposes only and may not be reproduced, reprinted or distributed without the written permission of the publisher.
