An excerpt from

Chasing Science at Sea

Racing Hurricanes, Stalking Sharks, and Living Undersea with Ocean Experts

Ellen Prager

Tales of Wonder

In the ocean there is wonder and mystery to be found. For my colleagues and me, the sea’s marvels pique our scientific curiosity and make us appreciative of evolutionary complexities. They can also provide an inspiring sense of discovery and at times just make us stop and take note of the ocean’s natural beauty and its seemingly endless parade of strange and mysterious life-forms.

For many people, just the sight of a dolphin, a whale, or even a shark can create a treasured lifelong memory. These, along with furry sea otters and playful sea lions, are the ocean’s charismatic creatures. Somehow, a scaly bug-eyed fish or gelatinous jelly just doesn’t seem to affect people the same way. For scientists that regularly go into the field, encounters with the ocean’s animals, charismatic or not, are often memorable and sometimes humbling. Having evolved to a life on land, our comings and goings in the ocean are nothing short of awkward and laborious. When underwater, we must bring our own supply of air and protection from the cold, the wet, and the increasing pressure with depth. We must use fins or a motor to propel ourselves with any sort of efficiency. Such inadequacies for a life undersea are never more apparent than when we are confronted by the agility and grace of the ocean’s own animals. When a sea lion swims effortlessly by, somersaults, hovers, and then blows bubbles in your face, it is a memorable moment, and one that highlights your own ineptness in the sea. When a dolphin or whale flicks its tail ever so slightly and is propelled powerfully forward, we are left amazed yet far behind, feebly kicking our feet or trying to start an engine. Such encounters make us more conscious and appreciative of how marine organisms have evolved so well to a life within the sea.

Personally, even a small squid can make me feel completely inadequate in the ocean and in awe of nature’s evolutionary accomplishments. Reef squid are typically less than a foot (0.3 m) long and have an elongated baglike body, a small rounded head with large eyes (one of the most advanced in the animal kingdom), and ten tentacles in front—actually eight arms and two tentacles. They also have thin, translucent fins that flutter along their sides, which provide stability. By pumping water through their body, squid can hover effortlessly or become instantly jet-propelled. They are also unequaled masters of camouflage and can change color in the blink of an eye. I have witnessed a squid go instantly from wholly translucent to polka-dot to pulsating with waves of red running through its body. Such versatile and complex traits make our own two-legged gait and monochromatic skin seem downright primitive.

Sometimes reef squid will approach if one stays still and quiet while underwater. They often travel in small groups that seem entrenched in an ongoing game of follow the leader. A lead squid may hover or move ever so slowly forward as the other squid literally line up behind and do the same. The leader may then wave a tentacle or two or change color as the others follow suit. They never get close enough to touch or hang around for long, but the company of the reef squid is a wondrous, humbling thing to behold, if even for just a few short minutes.

Other encounters with marine life have left me similarly intrigued and educated about the undersea world. Once while taking underwater photographs, I braced myself on what I thought was a rock only to soon discover a very surprised and sleepy sea turtle. Though sea turtles must regularly go to the surface to breathe air, some species can sleep underwater for up to five hours. The first time I encountered marine iguanas was another educational, if not slimy, experience.

Marine iguanas are found only in the Galápagos Islands. They are fascinatingly primitive-looking creatures, with leathery, wrinkled black skin, a small head and eyes, a pointed ridge down their back, and a body that tapers to a relatively long tail. They are usually found piled one on top of another basking in the sun along the islands’ rocky shores. Marine iguanas are named for their unusual ability to dive into the sea to feed on algae. As swimmers they are strange to behold, using a sideways swishing of their tails for propulsion. Their gastronomic ventures into the ocean, however, result in a bit of a dietary dilemma—too much salt. Thus, marine iguanas have evolved an interesting means of eliminating excess salt. They sneeze it out of their noses. If you get too close to or startle marine iguanas, they tend to sneeze more, and one must then be wary of flying lizard snot—learned this in the field as well.

While the sea’s creatures can amaze us, sometimes humans can equally inspire disbelief. At a marine laboratory in the Bahamas, my colleagues and I were once called upon to help when a pilot whale stranded on a nearby island. My friend and coworker Wendy Keith-Hardy, her stepson who happened to be visiting, and I responded. Arriving at the island, we found a relatively small pilot whale stuck on the beach. Whales and dolphins strand for a variety of poorly understood reasons, including sickness or injury, chasing fish or others in a pod into shallow water, or errors in navigation. No matter what the cause, to survive they must be returned to the water as quickly as possible. Large marine mammals dehydrate rapidly, and their body structure can’t support their massive weight on land.

The whale was what we expected; the line tied from its tail to a rock on shore was not. Our first job was to convince a local gentleman to untie the rope before it caused further damage. His plan, it seems, was to keep the whale in a pen that he would build adjacent to his bar/restaurant to attract customers. We quickly persuaded him that no one would come to see what would soon be a very dead whale. Did he really think it would survive long enough for him to build a pen? And then?

We untied the line and as the tide rose were able to gently push the pilot whale off the beach. Once in shallow water, it seemed disoriented and had trouble swimming. A short time later the small whale was moving about more steadily, but still seemed confused. We tried to guide it toward a channel that led to deeper water, but the whale repeatedly swam toward areas that would lead to another stranding. We then tried a new strategy. Wendy steered the boat on one side of the whale, while I got in the water and swam with snorkeling gear on its other side. I will never forget being eye-to-eye with that pilot whale, nor the power of its tail stroke. I had to take great care not to get within striking distance of its fluke. As I swam next to the whale, I hoped that it somehow knew we were trying to help. It didn’t go well at first, and the whale kept swimming in the wrong direction—some cattle-herding experience would have come in handy on this one. Thankfully, success came hours later when, after reaching deeper water, with one powerful thrust of its tail, the whale dove down and disappeared from sight. As we made the long boat ride back to the marine laboratory, we were all exhausted, yet rejuvenated by the experience and its outcome.


My friend and colleague Captain Phil Sacks tells of his own amazing whale encounter. Unfortunately, this whale was dead, but the experience is nonetheless one that he remembers well during an eventful voyage and amid a career chock-full of at-sea adventures. In 1986 Phil was working aboard a ninety-three-foot motor-sailing yacht in Greece. The yacht was a U.S.–flagged ship, and after America’s military bombed Libya, the crew was directed to return to the United States as quickly as possible, hopefully in time for a planned tall-ship event in New York to celebrate the Statue of Liberty’s birthday and restoration.

Just as they began shopping to provision the yacht for the voyage from Greece to New York, another international incident occurred—a major radiation leak from the nuclear reactor at Chernobyl. With winds blowing from the north, Greece was downwind of the leak, and people mobbed the markets in a panic, concerned about the safety of the food supply. Upon seeing the amount of food being bought by the ship’s crew—for seven people for six weeks at sea—the locals grew angry, assuming they were hoarding. The crew tried to explain, but their efforts were hampered by their poor command of the Greek language. They left Greece quickly, sailed to Majorca, Spain, then to Gibraltar and across the Atlantic to the Azores, and on to Bermuda, heading for New York.

For Phil the passage from the Azores to Bermuda was particularly memorable. They were one day out of the Azores and awoke to a calm sea with “a glassy ocean surface and just a slight greasy swell running.” With such a calm sea, the light plays tricks, and it can be hard to distinguish the horizon. On the other hand, floating objects are easier to see, and in the monotony of an ocean passage, sometimes just investigating a buoy can be an interesting distraction. That morning the lookout noticed something floating at the surface off the port bow, maybe a quarter mile away. They altered course slightly and approached the object. “It was a dead whale, bloated with air. But what really surprised us was that there were two large sharks swimming around the whale,” recounts Phil. The sharks weren’t just swimming around the carcass; they were actually sliding right up onto its back, almost to a point of being completely out of the water. It was a dead sperm whale, and while Phil can’t recall what type of sharks they were, he is sure they were large, deep-ocean predators about 10 to 12 feet (3 to 4 m) long.

At their previous port stop in the Azores, Phil had been in a bar in the old whaling port of Horta where an abundance of whalebones and teeth had been on display. Inspired, he decided to try to collect a few teeth from the whale carcass. Given the large sharks swimming nearby, Phil decided it probably wasn’t a good idea to launch their small boat for the job—it would be safer to attempt a tooth extraction from aboard the yacht itself. The sharks, however, did not want to share, no matter what boat they used. As the crew pulled alongside the whale and rigged up a line to lift the whale’s head closer to their reach, the large predators grew more aggressive, a little too aggressive, and in the end, the sharks won. Phil relinquished the teeth to a burial at sea when the whale eventually sank into the ocean’s depths. As they drifted away, he still remembers being utterly fascinated by the sharks’ behavior. In case you too ever happen upon a dead whale, it is now illegal to extract the teeth, or to trade or buy any part of a marine mammal.

As the yacht continued toward Bermuda, the swells disappeared completely, leaving the ocean as smooth as a sheet of glass. There was also a full moon, and for three full nights Phil recalls another amazing sight at the sea surface: “It was filled with hundreds of gelatinous animals, spiral forms, maybe over 12 feet [4 m] long.” He never saw the organisms during the day, but each night the sea was once again replete with the long, transparent creatures. There was no net aboard to collect a specimen, but after the voyage Phil described the organisms to biologists. He now thinks it may have been a massive aggregation of simple, barrel-shaped creatures called salps. Relatively recent observations from submersibles suggest another likely candidate—siphonophores. These are long, delicate, gelatinous creatures that can form chains up to 100 feet (30 m) long. To this day, Phil remains amazed by the encounter: “I have probably spent something close to 3,000 nights at sea, but have never again experienced anything like it.”


After dark the sea is indeed a very different place than during the day. Underwater, just the progression from day to night can be striking. As dusk falls, the shallow ocean begins to turn dark, and it becomes a time of shadows, when many of the sea’s visual predators most actively seek their prey. As darkness more fully overtakes the ocean, nocturnal animals begin to emerge while their daytime counterparts seek refuge. In the full of night with heavy cloud cover or a new moon, even the shallow sea turns inky black. However, on moonlit nights the upper reaches of the ocean can remain amazingly bright. On one late-night boat ride across a shallow bank in the Bahamas, the moonlight was so bright, the water so clear, and the underlying sand so white that we could see stingrays and fish swimming below as we raced by. The nighttime ocean is particularly dramatic on a coral reef.

At night many creatures on a coral reef, such as octopus, moray eels, and the light-shy squirrelfish, swim about more freely. And corals, most of which look like lifeless rocks during the day, become more active after sunset. Most corals are colonies of small animals called polyps, each of which is essentially a stomach surrounded by a ring of short tentacles. At night the coral polyps extend their tentacles into the water to feed on particles and small organisms drifting by. When a diver’s light is held over a coral at night, it creates an astonishing sight. Zooplankton and small fish attracted to the light soon fall prey to the coral in what can only be called a tentacular feeding frenzy. At night under the glare of a light, colors on the coral reef also appear enhanced: the red of a sponge becomes rich and especially vibrant, the green of an octopus or moray eel turns luminescent, and the yellow of a seahorse seems startlingly bright.

Marine scientist and long-time diver Steve Gittings is currently the science coordinator for the National Marine Sanctuary Program. His choice for one of the ocean’s most amazing sights is a nighttime wonder that can be seen only once a year at a very specific time—it is the mass spawning of corals. Mass coral spawning is a somewhat mysterious phenomenon that was first discovered on the Great Barrier Reef in 1982. In the Gulf of Mexico’s Flower Garden Banks National Marine Sanctuary, it occurs eight days after a full moon in August, at around nine o’clock at night. Nearly all at once, a huge number of boulder or head corals release countless bead-sized bundles into the water. Steve says, “The crystal clear water is turned into a soup of ascending spheres that envelopes awe-struck divers who then rush in to record the event with all sorts of cameras and data collectors.” Each bundle released contains both coral eggs and sperm, but somehow the sperm doesn’t fertilize the eggs from the same parent. Once the bundles have floated to the surface, they break apart, and the sperm can then find an egg from another parent coral, “putting into motion the life of a potential new coral colony.”

While mass spawning is incredible to observe, Steve also finds the underlying reproductive process fascinating. Throughout the world, many reef corals reproduce only once a year, and while this seems simple enough, it is complicated because absolute synchronization among individuals is essential. For the corals to successfully cross-fertilize, gametes (sperm and eggs) from different individuals must be released at nearly the same time; otherwise, viable offspring will not be produced. For Steve it is an amazing coral choreography, one that takes place without eye contact, words, or even an enticing mating dance.

Successful mass spawning of corals may also be an indicator of their health and potential to remain viable. With so many of the world’s coral reefs showing evidence of degradation, Steve believes that continued mass spawning on the Flower Garden Banks is a good sign. He also strongly believes that ensuring good water quality over a reef is critical to nature’s own approach to coral reef management and proliferation—mass spawning.

The Flower Garden Banks National Marine Sanctuary was established to protect and allow for the study of the region’s coral reefs and other undersea life. Because of its location, some 110 miles (177 km) south of the Texas and Louisiana coasts, the sanctuary has become a popular diving and research destination. Yet only a lucky few scientists or adventurous divers get to witness the wonders of mass spawning at the Flower Garden Banks, on one very special night of the year.


Nighttime also provides the opportunity to observe one of the most spectacular and fascinating displays in the ocean—bioluminescence, or the production of light through biological processes. Researchers have discovered that a surprising number of the sea’s creatures have the capability to produce light. It occurs in a variety of forms; the most common is a tiny twinkling created by small planktonic creatures called dinoflagellates, which typically produce light in response to water motion. A producer on a television show about the Bermuda Triangle once asked me about a mysterious glowing sphere reportedly floating near a boat just before it was lost. She was surely hoping for a dramatic response, something along the lines of the supernatural, aliens, or an unexplained mystery. My answer—jellyfish, which create another common form of bioluminescence. They often produce spherical bursts of bright blue-green light. Though it is not fully understood, scientists believe that organisms in the ocean use bioluminescence for several purposes, including as a decoy to escape, to hide from or startle predators, as a form of communication, and as a means to lure in prey.

Deep-sea biologist Edie Widder, cofounder of the Ocean Research and Conservation Association, was originally planning a career in molecular or neurobiology. One wondrous dive in the deep sea, however, changed her career path and led to her becoming one of the world’s leading experts on bioluminescence. It was the early 1980s, and she was doing her first dive into the deep ocean in a tethered deep-diving suit, which she likens to being the yo-yo on the end of a very long string. Edie expected to see some bioluminescence in the water during the dive, but when she turned off the suit’s outer lights, the display around her was staggering. The sheer number of light-producing creatures was far beyond anything she had ever imagined. As she stared at the bright flashes occurring throughout the water column, she pondered the role of bioluminescence in the sea. Edie vividly remembers thinking that if so many marine organisms can create light, it must play an important, yet unrecognized, role in the ocean. It was a life-changing moment, and she has since spent her career studying and quantifying bioluminescence in the sea. She is now using this expertise to help conserve coastal areas. Her story about using fake bioluminescence to lure in a new type of squid is in chapter 5.

Bioluminescence is also a great crowd pleaser. Aboard SEA ships, a large net is regularly towed deep in the sea at night to collect organisms for teaching and research. The midwater or twilight region of the ocean, between depths of about 600 and 3,000 feet (200 to 900 m), is typically targeted. Many of the sea’s animals migrate upward into shallower water at night; hence nighttime tows enable easier collection of deeper-water species. The highlight of such tows is unquestionably the display of bioluminescence during the retrieval process. As the net is pulled in, a ghostly green glow appears far off the ship’s stern. As the net gets closer to the surface, the glow intensifies, and quick bursts or flashes of green light occur within. This incredible light show often continues until the net is under the glare of the ship’s lights.

Once the net is onboard, there is the fun of seeing what strange creatures have been ensnared. Students wash, pick, and sieve through all that is caught, counting and identifying as much as possible. Some of the organisms are easy to identify, such as the bright red shrimp that live in the midwater region of the sea. A toothy viper- or hatchetfish is always an interesting find—luckily they are just a few inches long. Other organisms are less easily identified, having been smashed by the effects of the net tow—much like a washing machine’s spin cycle—and the result is typically copious amounts of slime, fondly referred to as sea snot.

On one cruise a surprising example of blue bioluminescence sparked a late-night adventure in marine biology. While helping students pick through the results of a nighttime net tow, I observed a small flash of brilliant azure blue in the bucket. Startled, and curious as usual, I had to know what had created the flicker of light. We watched and waited for it to happen again, at the ready to collect the culprit. With the next flash of blue, we tried using a small net, a spoon, and even an eyedropper to scoop up the responsible creature. I honestly don’t remember how we finally caught it, but the challenge definitely tested our patience late into the night. Our efforts were finally rewarded when we got the animal into a petri dish and under the microscope. It was small, about half an inch (a centimeter or so) long, oval-shaped, and appeared as if bejeweled with colorful gems. Each of the animal’s multiple segments was a different and vibrant color. Unfortunately, the spectacular tint soon vanished, and the tiny animal became entirely transparent. The students and I spent hours searching through the ship’s library of books to identify the beautiful creature. We eventually found it, a copepod aptly named Sapphrina. Although the organism was not new to science, for us it provided a marvelous evening of wonder and discovery.


For oceangoing scientists, wonder often goes hand in hand with discovery. Relatively few scientists discover a new species or are the first to explore a particular habitat. Yet for most scientists, myself included, we feel an inspiring sense of discovery when seeing things for the first time, whether they are new to science or not. Caroline Rogers, a marine ecologist for the U.S. Geological Survey in the U.S. Virgin Islands, has spent years studying Caribbean coral reefs. Of the first time she dove on a coral reef in the Pacific, she says, “It was nothing less than a spiritual experience.” Seeing the unmatched diversity of color and species of coral in the Pacific as compared to the Caribbean provided her with an incredible sense of discovery.

Chuck Messing, a marine invertebrate zoologist at Nova Southeastern University’s Oceanographic Center, studies crinoids, the ocean’s flowerlike sea lilies and feather stars. Whether on scuba or in a deep-sea submersible, he is always on the hunt for a crinoid, or any invertebrate, that he has never seen or studied before. On a trip to Australia’s Great Barrier Reef, one of his most memorable scuba dives was in an open sandy area, because there he found an unusual species of crinoid. Chuck notes, “Who goes to the Great Barrier Reef to dive in sand?”

Bob Ginsburg vividly remembers the first time he landed on the west side of Andros, an island in the Bahamas. For years he had been studying thick sequences of ancient rocks on land made of fine calcium carbonate, which exhibited strange features, such as filled-in cracks and intraclasts (chunks of a lower deposit found “floating” in the rocks above). At Andros, Bob found that the island’s extensive tidal flats were covered with mud cracks and loose chips of mud; these were the precursors to the features he had been puzzling over. He was face to face with the modern equivalent of his ancient rocks. Given the great expanse of the corresponding rock formations, Bob also realized that tidal environments similar to those on Andros were much more extensive in the past than they are today. He published a series of research articles based on those early days at Andros and still remembers the feeling of awe and discovery during that very first visit.

Shirley Pomponi, a deep-sea biologist at the Harbor Branch Oceanographic Institution, recalls the incredible sense of discovery she felt when seeing deep-sea sponges from a submersible for the first time. She was also amazed to find that the sponges looked just like the drawings done of them—100 years ago. The artists had never actually seen what she was seeing—the deep-sea sponges in their natural environment. Their beautifully colored drawings were based only on dredged samples, which must have been heavily damaged and filled with mud. Yet incredibly, the sponges Shirley saw in the deep sea looked just like the old illustrations.


Things in the ocean that are cute, big, scary, or glowing are a sure hit with just about any audience, but it is a bit more difficult to convince others, especially students, that something as simple as sand can be equally as delightful. During my tenure at SEA, I conducted experiments on the dynamics of carbonate and quartz sand grains, testing the flow strength that would initiate transport in a runwaylike flume at the Massachusetts Institute of Technology. To collect sediment samples for the experiments, I enlisted the help of my students on an SEA cruise. I was particularly enthused about a certain type of sand from the Bahamas. The students, however, did not share my zeal, often gracing me with the classic rolling of the eyes when I spoke about the magic of ooids.

Ooids are small, white, beadlike grains of calcium carbonate that form in only a few places in the world today, but were more prevalent in the geological past. Underlying Miami, for instance, is a rock formation appropriately named the Miami oolite—a rock made of ooids. One of the largest oil fields in the world today is a reservoir of ancient limestone composed of—ooids. Over the years, geologists have debated whether ooids form strictly by chemical precipitation from water supersaturated with calcium carbonate or through biological processes facilitated by bacteria. Either way, these very round, very white beadlike grains form as multiple layers of calcium carbonate crystals accumulate around a nucleus. Conceptually, ooids are simply interesting, but when one jumps out of a boat and sinks knee-deep in billions of them it is truly special—really!

The SEA ship arrived at Joulter’s Cay in the Bahamas, and with my skeptical students at the ready, we launched a small inflatable boat on a mission to collect ooids. The students continued to shake their heads and roll their eyes over my excitement as well as the large collection of plastic tubs and bags that I had brought along for storing samples. We motored to the shallow water just off the beach, and I enthusiastically jumped out of the boat, sinking into billions of ooids. The students handed me several bags and containers, which I began filling with the beadlike grains. Several students then decided that they too wanted to experience ooids firsthand. Jumping out of the boat, they sank knee-deep, and their expressions were nothing short of glee. Soon they too wanted bags for collecting—it turns out that ooids are pretty cool, even for the nonscientist.


In 1997 marine biologist Bill Sharp of the Florida Fish and Wildlife Research Institute was investigating an unprecedented bloom of sea urchins (Lytechinus variegatus) in Florida Bay. He asked me to examine the geological effects of the event. I went into the field expecting to see just a few more of the prickly echinoderms than usual. What I found was nothing short of astonishing. There had to be hundreds, so many sea urchins that they were literally piled up, one on top of another. Not only was their sheer number surprising, but so was the impact they were having on the seafloor. It was as if an army of out-of-control lawn mowers had marched through the seagrass. In front of the sea urchins stood a meadow of lush, long-bladed green seagrass, while in their wake all that was left was bare sand and mud. From a geological perspective, the grazing by sea urchins had left the sediment more vulnerable to erosion and resuspension, but why the population bloom occurred and how often it happens remains a mystery. It was a sight I will never forget.


Linda Glover, an oceanographer and policy expert who spent many years working for the Oceanographer of the Navy, tells of her own at-sea wonder. At the time she was using satellite images and ship observations to make weekly estimates of the position of the Gulf Stream and its eddies for the National Weather Service. Linda decided to see just how accurate their position estimates were during a recreational sailing trip from Norfolk, Virginia, to Bermuda. With a fax of their latest analysis in hand, as they were sailing east and approaching the predicted position of the Gulf Stream, she began using a bucket over the side and a thermometer to measure ocean temperatures. It was a calm, sunny afternoon, and she expected to detect an abrupt rise in temperature as they hit the “West Wall” of the current. “Looking ahead of us, we suddenly saw the wall,” she recalls. Stretching along the horizon for as far as she could see in both directions was a distinct change in water color and a literal step up in the sea surface. The warm, lower-density water in the Gulf Stream had actually created a small wall on the current’s western edge. Linda estimates it was about a foot (0.3 m) or so in height. Happily for her, the actual position of the West Wall also coincided fairly well with their predicted location based on the satellite data. Just the right conditions were needed for Linda to actually see the Gulf Stream so dramatically; more often than not it is visually undetectable and sometimes can create truly nasty sea conditions for boaters.


Mel Briscoe, a long-time oceanographer with the Office of Naval Research, an expert on interagency ocean policy, and a dive instructor, has a different, though no less interesting, perspective on an ocean wonder. To set the stage, he explains that in the 1960s there was a new vision in physical oceanography—to measure deep-sea currents over a long period of time with instruments and data loggers attached to ocean moorings. Moorings are essentially a long cable with oceanographic instruments attached at points along its length. Each can be several miles long, with a large buoy at the surface, and is anchored by a heavy weight at the bottom. Prior to that time, oceanographers had used only primitive mechanical equipment for current measurements in shallow coastal waters for just a few days.

Mel likens the safe launching of a mooring in the deep sea to a beautifully choreographed, but dangerous, ballet. The stage was the fantail of a ship, an open deck where large, heavy equipment could be lowered into or lifted from the sea. It was a venue that could be rolling in the seas or awash with water as waves broke over the side. And the mooring anchors weighed tons, literally, while the buoys were large and cumbersome to move. It was precarious work and no place for the light-hearted. The players were, as Mel puts it, “strong men in rubber boots with knifes on their hips, directed by the chief scientist, and stage-managed by the ship’s bosun.”

For Mel the deployment of a mooring by the ship’s crew was a true wonder. A large buoy would first be lifted by a crane, swung over the side, and lowered into the water with the upper part of the mooring line already attached. The crew used lines that went through a cleat to the buoy to safely keep it from swinging uncontrolled and becoming a deadly battering ram on deck. While one person handled the line, a second watched to ensure that no one was standing in a loop, or bight, that could ensnare a foot and, in an instant, drag that person over the side. Safety railings or lines at the deck’s edge were forfeited to avoid interfering with the equipment going over the side. Instead, each deckhand working near the edge had a person standing behind them hanging onto their belt, just in case.

The mooring line was spooled out from a large winch as the ship moved slowly toward a designated research site. At specific spots along the cable, as determined by the research plan, a current meter was attached. Mel recounts, “It took five deckhands to dance this part of the ballet. Four to attach the instrument and one observer making sure no parts were missing or faulty.” He remains amazed that only a few moments were needed for the ship’s crew to attach a current meter and then continue, as the cable was rapidly spooled out. It took hours for a mooring to be deployed in its entirety; each could be 16,400 feet (5,000 m) long and have twenty current meters attached. Interspersed along the cable were also large flotation devices—heavy glass balls in plastic shells—to balance the weight of the mooring line underwater. Throughout the process the actors in this ballet would change, substitutes made as someone went off the deck for a rest or to refuel.

Just before the final act, the anchor would be attached. By this time the mooring was stretched out behind the ship for miles, floating into the distance with the line, current meters, and glass balls all being dragged along. At the designated position for the mooring, the anchor would be pushed over the side and instantly drop to the bottom, pulling the cable, instruments, and buoys along with it.

With a well-performed ballet, the mooring would be in the right location and at the right depth, and all the instruments would be in working order. Given the high cost of ship time, the crew would work night and day deploying moorings on each cruise, sometimes up to twelve. A year later the ship would return to recover each mooring, and the scientists would download their data from the instruments. The recovery operation required another ballet, and this one could be even more dangerous. Mel fondly remembers his time at sea deploying moorings: “It was all quite beautiful to watch and exhilarating to be a part of.”

These days similar long-term mooring deployments are still done, but now instruments can be programmed to transfer their data to a buoy at the surface, which can then transmit the data via satellite to laboratories on shore and across the globe via the Internet.


Two last, equally wondrous and thought-provoking tales about the marvels of the sea—in this case very large ones, namely whale sharks. The first comes from Steve Gittings and an experience in Belize several years ago while he was working with colleagues studying spawning aggregations of groupers. They were diving at just about sundown, and the ocean was starting to turn dark. Steve could see schools of large fish gathering below—fish that usually swim alone on a reef. Soon there were hundreds, maybe even thousands, of these fish, slowly rising toward the surface, in one enormous and growing school. Steve was surprised as all around him “they swam in slow circles at first, gradually increasing their speed and forming tighter and tighter spirals, creating a living tornado.” He was a bit disconcerted as the fish got closer and closer, especially the four-foot-long cubera snappers with exceptionally large, sharp teeth protruding from their mouths, clearly oblivious to everything but spawning. They were constantly changing color, becoming dark and then light, until the apex of activity when they released eggs and sperm into the water. The visibility for the divers instantly became negligible, and then as Steve watched in “shock and awe,” out of the blue lumbered a giant whale shark, its huge mouth opened wide as it swam slowly by, dining on the surrounding soup of caviar. Then another whale shark swooped through, only to be followed by more of the monstrous planktivores. During his twenty years of diving, Steve had seen a few solitary whale sharks, but he had never encountered anything like this. It was truly one of the highlights of his career in marine science—so far.

The experience also made Steve think about a recent report suggesting that a high percentage, possibly as great as 90 percent, of the large fish in the ocean have been fished out. Was he witnessing an event that was once fairly common in the sea? If overfishing continues, would his kids know about such miraculous spawning events and whale sharks only as stories told about times gone by?

The second, no less awe-inspiring, whale shark tale comes from marine biologist and shark expert Bob Hueter of Mote Marine Laboratory. For over ten years, every spring, Bob and his colleagues had been going to Mexico to study sharks. The shallow lagoons of the area are nursery grounds for blacktips. With long hours in the field and by working with local researchers and fishermen, they were able to learn a great deal about the sharks’ life cycle, behavior, and movements. One day, about four years ago, while sitting in a boat, Bob was chatting with a local fisherman who had become a trusted and helpful partner. Out of the blue the fisherman said something to the effect of, “Bob, you do know that each year after you leave there are whale sharks and manta rays all over the place?” Bob was stunned and couldn’t believe that no one had ever mentioned it. He had always wanted to study whale sharks, but they tend to be hard to find.

Four years later, over the course of essentially three summers, Bob and his team of researchers had tagged some 550 individual whale sharks in an area now believed to host the largest aggregation of whale sharks in the world. From May to September of each year, perhaps 1,500 whale sharks congregate off Isla Holbox, Mexico, to feed on an abundance of plankton produced by upwelling in the region. Bob recalls one field session in particular with the whale sharks. The enormous creatures were in an area of exceptionally clear water, and his team was in the midst of tagging, measuring, and collecting as much data as possible. In a moment of inspiration, Bob instructed the team to drop what they were doing and simply swim, watch, and appreciate the magnificent creatures all around them. He says it was unforgettable, “like having three 35-foot buses at your sides. Yet they are gentle, graceful animals unbothered by your presence.” By just stopping and taking the time to appreciate and observe the whale sharks, Bob was also able to learn about them. He had previously thought that their eyes were located strictly on the sides of their head, which would create a puzzling problem—a huge blind spot at their front. How then, did these enormous animals avoid running into things as they swam slowly through the sea filtering out plankton? With closer observation that day, he realized that their eyes are in fact rolled slightly forward and to the side; they can see what lies directly ahead without a problem. There is great power in simple observations in the field, yet sometimes we forget how much there is to learn just by watching. Bob’s story also illustrates the benefits that scientists can obtain from working with local people who spend much of their time in the field and are willing to share their knowledge.


From biological marvels to surprising physical and geological features, the sea is a place of wonder. For scientists, encounters at sea bring to life what we spend hours and hours reading about in a library or studying in an office or laboratory. Such occasions make us contemplate how organisms have evolved and adapted to a life in the ocean and about our own relationship to and impact on the sea. Experiencing the ocean’s amazing wonders firsthand is one of the great and precious benefits of doing science at sea.

Copyright notice: Excerpt from pages 25–44 of Chasing Science at Sea: Racing Hurricanes, Stalking Sharks, and Living Undersea with Ocean Experts by Ellen Prager, published by the University of Chicago Press. ©2008 by The University of Chicago. All rights reserved. This text may be used and shared in accordance with the fair-use provisions of U.S. copyright law, and it may be archived and redistributed in electronic form, provided that this entire notice, including copyright information, is carried and provided that the University of Chicago Press is notified and no fee is charged for access. Archiving, redistribution, or republication of this text on other terms, in any medium, requires the consent of the University of Chicago Press. (Footnotes and other references included in the book may have been removed from this online version of the text.)

Ellen Prager
Chasing Science at Sea: Racing Hurricanes, Stalking Sharks, and Living Undersea with Ocean Experts
©2008, 178 pages, 4 color plates, 28 halftones
Cloth $22.50 ISBN: 9780226678702

For information on purchasing the book—from bookstores or here online—please go to the webpage for Chasing Science at Sea.

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