Kraken

by Wendy Williams

By 7 p.m., Julie had finished tagging. The shoal of Humboldts was still churning up the water all around the boat, so the team decided to harvest squid stomachs. By recovering the contents of the stomachs for later lab study, the team would move a step closer to answering another pressing question: What do Humboldt eat while they’re in Monterey Bay? Some researchers had found a correlation between declining numbers of hake—a Pacific whitefish that often ends up in fish sticks and other assorted fish products—and the presence of large numbers of Humboldts. The scientists wanted to harvest the Humboldt stomachs to confirm those findings.

  Stewart uncovers the squid’s beak

  Julie cut the brain stem of each squid with a knife, right below the head. She didn’t seem to mind. “Field biology itself selects for human researchers with particularly rare characteristics,” molecular biologist Sean Carroll once wrote. In Julie’s case, that seems to be true. She spent the rest of the evening working on another fifty or so Dosidicus specimens, measuring their lengths, severing their brain stems, and cutting out their stomachs.

  When the researchers hauled the squid on board, the animals continued to flash red and white colors by using their chromatophores, but when Julie made her cut, the squid’s body turned from red to white in milliseconds. The tentacles, however, with their own sets of nerve cells, remained red. “The nerves from the brain to the tentacles don’t go through the part of the brain she cut,” Gilly explained later. “When you cut behind the head you’re severing the anterior and posterior parts of the animal from nervous control. But not the arms.”

  CHAPTER SIX

  LUMINOUS SEAS

  It’s almost like their skin’s covered in television screens.

  —MARK NORMAN, AUSTRALIAN CEPHALOPOD SCIENTIST

  ustralia’s Great Barrier Reef is the planet’s largest living superorganism, a 1,600-mile, coral-based amalgam of thousands of living species that depend on each other for survival. Among these are more than four thousand mollusk species, including hundreds of species of cephalopods. Some of them have been identified, but many have not. Finding out what’s there is an immense undertaking.

  Among those trying to accomplish this goal is Australian researcher Mark Norman, who has identified more than 150 new mollusk species. Also an expert underwater photographer and videographer, Norman has dazzled people around the world with his work, which shows the profound variety of colors, shapes, and lights that can be used by cuttlefish, octopuses, and squid. His work has brought the once-arcane subject of cephalopods out of the science labs and into the public eye. It was Norman’s video of a coconut-shell-carrying octopus that wound up on YouTube and went viral, enjoying more than a million views in only a few weeks. Knowing I would be interested, at least twenty different people sent it to me.

  Later Norman and his colleagues published a paper on the phenomenon, calling it “tool use,” since the octopus seemed to be carrying the shell around for future use as a shelter. In the video, the octopus carries the shell directly under its body by gripping it with some of its arm suckers. The animal then moves across the seafloor by walking on some of its arms, a difficult and burdensome activity that the scientists dubbed “stilt-walking.”

  Another Norman video that shows a mimic octopus that could change shape and color, appear and disappear before viewers’ eyes in only milliseconds, has been seen by more than 500,000 people. The ocean is a riot of color and light, and no group of animals makes better use of the available palettes and shadings and light shows than do the cephalopods. Some, like cuttlefish, use rich repertoires of colors on their skin, lots of letters in their alphabets, to communicate, causing Norman to equate their skin with television screens. But cephalopods use much more than color when they call upon their quick-change, now-you-see-them, now-you-don’t artistry.

  Most of the ocean, down below the surface, is dark—darker than the darkest night. Strong sunlight penetrates only to the top several hundred feet. Most light has disappeared by 600 feet down. Below that layer is a mysterious netherworld of half-light, the twilight zone. Several thousand feet below the surface, even that tiny bit of light has disappeared. Instead, this world is filled with pinpoints of light—light not from the sun, but from whatever life is down there. If you could swim in this world (you can’t because the pressure would kill you), it would seem as though you were a spaceship swimming in a light-filled ocean of twinkling stars.

  In many ways, the sea is more celestial than earthly. These pinpoints of light—bioluminescence—come from the life that thrives in the water. In the sea, the ability of animals to make their own light is more the rule than the exception. Probably about 90 percent (or more) of the ocean’s species can produce some kind of glow. Sea life uses this light in a wide variety of ways—as illumination in the dark sea depths, as a way to lure prey, as a way to confuse predators and gain time to escape, as a communication strategy, and even as a sexy statement to other members of its own species.

  Twenty-five hundred years ago, Aristotle, arguably the world’s first marine biologist, wrote about the strange “cold” lights in the ocean, and we have been attracted by the light show ever since. People have found ingenious ways to use this biological phenomenon. Some indigenous tribes captured animals that glowed in the sea and used them as “flashlights” to light up nighttime paths through the forest. In Paris in 1900, one inventor filled a glass bulb with a glowing bacterium that’s quite common in the sea, Vibrio fischeri, and used it to light the interior of a room with a strange, otherworldly glow. We ourselves like to mimic this phenomenon: Around the holidays, when the northern half of the planet is at its darkest, we string tiny blinking lights on our houses and down our streets to comfort us until the sun begins to return. Perhaps our fascination with tiny lights twinkling in the dark is vestigial.

  That the sea should be filled with light isn’t surprising, since sensitivity to light was one of life’s earliest characteristics. A simple response to light, angling toward the rays of the sun, is elemental. Even plants do it. The ability seems to have been built into the structure of simple one-celled animals. In recent decades, researchers have discovered one particular gene (sometimes called “eyeless” because without it there would be no eye) that’s present in such a wide span of animal life—houseflies, mice, simple wormlike sea animals, cephalopods, and us—that they believe this gene has existed since evolution’s early days. The eyes in the animals with this gene are not all alike, nor are they all equally efficient. But the presence of very similar eyes in so many species points toward one of science’s most momentous breakthroughs: understanding the universal interweaving of all life. We know about evolution from Darwin’s point of view, but in recent years scientists have come to tease out the details of the fundamental basis of genes and of DNA. And it turns out that, in this fundamental sense, there’s nothing new under the sun: The genes that helped make early proto-eyes are also present in our own bodies, in modified form, and they’re the reason why you can see well enough to read this book.

  The ocean’s light shows have always attracted our attention, but no one until very recently realized that this radiance could create a revolution in medical research that would save human lives, winning scientists a Nobel Prize in the process. In the 1960s, a young Japanese scientist, Osamu Shimomura, working at Friday Harbor Laboratories near Seattle, Washington, was curious about why a certain kind of jellyfish swimming in nearby waters gave off an unusual green glow. He found that the glow was caused by a specific and unusual protein, which he identified.

  Shimomura published his finding, which was largely ignored for several decades. Then another researcher, Douglas Prasher, learned how to manufacture very large amounts of this protein in his laboratory. For the first time, it was widely available to other scientists. Then two other researchers figured out how to use that strange glow to light up proteins inside an important type of brain cell, the neuron. The green light allowed neuroscientists for the first time to watch the inner workings of the neuron on a v
ery basic level, on the level of molecules at work inside the cell.

  By “tagging” or attaching the protein that lit up green to the other molecules at work inside the cell, researchers could watch those now-glowing molecules do their day-to-day jobs, keeping the neuron functioning. Today, hundreds of researchers are using this breakthrough to study what goes wrong in neurons when people develop diseases like Alzheimer’s or Huntington’s.

  Fascinated by the green light—called “green fluorescent protein”—Yale University neuroscientist Vincent Pieribone wrote a book explaining the wide-ranging importance of Shimomura’s serendipitous and seemingly (at first) unimportant discovery. To Pieribone, scientists are voyeurs who try to spy on the long list of “individuals” at work keeping things shipshape inside cells. “Proteins are the workers of the body,” he told me. “They have these little individual personalities, like the guys who pick up the garbage, the guys who drive the trucks. We want to know as much as we can about the lives of these proteins, these amazing little guys. What’s their lifestyle like? Do they change their personalities?”

  The key to this breakthrough is that the green fluorescent protein can illuminate these various individual proteins without disturbing their activities. It’s kind of like asking some members of a crowd to carry light sticks so observers can follow them in the midst of the mass and see where they go and what they do when they get there. “This has transformed science and medicine,” Pieribone continued. “Now, we can look inside a brain cell with molecular specificity.” Formerly, researchers had to destroy cells in order to study them, so that a scientist might be able to look at an individual protein frozen in time but wouldn’t be able to see what the protein’s job was. Using the new tagging technology from the jellyfish, Pieribone and hundreds of others now watch the many protein-workers in real time as they move things around in cells, as they clean up messes, or as they repair damage.

  I asked Pieribone if anyone expected a jellyfish to help find a cure for neurological diseases back in the 1960s, when the phenomenon was first discovered and reported to the scientific community.

  “No,” he answered. The original scientist had just been indulging his own curious nature: Why did that particular species of jellyfish display a particularly unusual green glow?

  “Very interesting findings come from very strange places,” Pieribone concluded.

  The breakthrough, he added, took a series of scientists several decades to discover, and comes under the category of “obscure studies that made huge contributions to the world.”

  Some squid research exemplifies this pleasantly serendipitous phenomenon quite well, he said, adding that it would be an enormous mistake not to study the animals: “It’s been exhilarating to learn how bizarre the world is under the ocean. I happen to have a huge fascination with squid. When I see them when I’m diving, I try to get as close to them as possible. You recognize that they have a certain level of intelligence. They and other animals in the ocean can provide fantastic tools that don’t exist in our own world. We can capture these tools from other animals and have amazing libraries of solutions.”

  “Amazing libraries of solutions …” I thought it was an interesting concept, well put. Jellyfish, of course, have contributed green fluorescent protein to our modern medical toolkit.

  Other sea life has been equally helpful. Only recently, Japanese researchers developed a very promising treatment for women suffering from advanced breast cancer. The new medication derives from DNA taken from a species of sponge. There are plenty of other examples, and, Pieribone says, we’ve only seen the tip of the iceberg.

  Cephalopods are the masters when it comes to creating light shows under the sea. They can use light to disguise themselves, to hide from predators, to lure prey into their waiting arms, or maybe, sometimes, just to see better. Their strategies for light-manipulation seem to be boundless. Julie’s Humboldt squid was covered with bioluminescent photophores—small, light-emitting packets embedded all over the animal’s skin. Another squid, Heteroteuthis dispar, a tiny deep-sea squid, is nicknamed “fire shooter” because, instead of shooting out a cloud of ink to confuse predators, as do many cephalopods, it shoots out a cloud of light. The sudden, unexpected light distracts the predators, buying the squid enough time to jet away. Perhaps the combination of genes that triggers the fire shooter’s remarkable behavior could one day be used to help us in some way.

  The colossal squid, which probably lives about 3,000 feet below the ocean’s surface, has eyes that can grow to nearly a foot in diameter. Attached to the back of the eyes are bioluminescent “headlights” that provide extra light. The “headlights” help the animal attack its prey in the darkness of the deep ocean by providing enough light for the animal to judge the distance from its eyes to the attack point.

  The truly weird, eight-arms-but-no-feeding-tentacles squid Taningia danae specializes in shock and awe. It has large bioluminescent organs on its arm tips that flash just when the animal attacks. Scientists think the light may perform two functions: confusing the prey and establishing the correct distance of attack.

  In the mid-level layer of the ocean where some sunlight penetrates, squid have developed a strategy called “counter-shading” to protect themselves from predators. Clyde Roper and other scientists have found that some species of squid can produce light on the ventral, or lower, surfaces of their bodies. The animal is able to make the level of light coming from its lower-surface photophores match the level of sunlight in the water above so that the animal disappears. Predators looking up from deeper in the water see a dappling of light coming from the rays of the sun. The animal’s belly produces the same dappling, so the predator sees nothing to break the pattern of the sunlight. Roper and his colleagues also learned that the animals can change the amount of light coming from these lower-surface photophores within a matter of seconds. When the scientists changed the level of light coming down from above an experimental animal, within half a minute or so the squid adjusted the amount of light coming from its lower-surface photophores, continuing to match the light from above.

  Meanwhile, despite the amount of light coming from above, the dorsal, or top, surface of the animal remained dark. Predators swimming above, looking down into the ocean depths, saw only black.

  The light of bioluminescence comes from chemical reactions. Squid can produce light in different ways, but often call upon friendly bacteria to do the job for them. From the point of view of the squid, the bacteria living inside its body are a worthwhile investment because the payoff of added light helps the squid thrive. From the perspective of the bacteria, the squid provides room and board. It seems to be a happy marriage of satisfied coequals.

  “It’s a deep conversation between two partners,” Margaret McFall-Ngai explained to an audience in a Marine Biological Laboratory auditorium one hot July evening in 2010. The weather was sweltering and the lecture hall had no air conditioning, but her remarkable talk, “Waging Peace: Diplomatic Relations in Animal-Bacterial Symbioses,” easily held the attention of several hundred scientists. This was cutting-edge stuff.

  She was explaining that bacteria living in host animals aren’t just hitchhikers looking for a free ride. They give something back to the host, although the relationship can be pretty complex. For example, in humans, a certain type of bacteria that’s essential to intestinal health and, strangely, the third wave of the sleep cycle, can also cause whooping cough and gonorrhea.

  Scientists suspect that the bargain between bacteria and host has been present from the earliest days of evolution, since bacteria in one form or another have been around for well over a billion years. In fact, from the point of view of bacteria, the purpose of evolution might be simply to provide the bacteria with a wider array of housing options.

  Since both humans and squid act as host animals to bacteria, findings from studying squid and bacteria can help further human medical research. The work done by McFall-Ngai and her colleague Edward Ruby has even helped do
ctors understand why, whenever possible, human babies should be delivered naturally, rather than by cesarean section.

  “We are not the single individuals that we think we are,” McFall-Ngai told me. “You have all these bacteria living with you that are required for your health. I study squid, but the major focus of my lab is to inform the biomedical community as to how bacteria form these persistent relationships with animal cells.”

  McFall-Ngai has shown this by studying the Hawaiian bobtail squid, Euprymna scolopes—“the couch potato of the squid family.” Temperamentally, the bobtail squid is a rather laid-back little animal. Full-grown, this unobtrusive fellow is small enough to fit in the human hand. To me, its behavior more closely resembles that of cuttlefish than of the Humboldt. Because of this, it’s easier to keep in a research laboratory than a more reactive squid.

  Unlike most squid, the bobtail squid spends much of its daylight hours buried in the sand. When the sun goes down, the bobtail comes up. It begins hunting for prey. This is a good protection strategy, but the vulnerable little animal, lacking the ability to move quickly, needs help in order to survive. Although it hunts at night, moonlight and starlight make it visible in the shallow waters it favors, making it both vulnerable to predators and avoidable by prey.

  To solve the problem, it camouflages itself by acquiring bacteria that give off light. This sounds counterintuitive, but it turns out that this teamwork between squid and bacteria pays off: The light from the shining bacteria carried by the squid helps the host squid better blend in with the light from the moon and stars above.

  The squid has even evolved a special place to house the bacteria—a structure scientists call a “light organ” located inside the mantle. But the bacteria don’t just set up house and begin to party. When the first batch of bacteria arrive in their new digs, they have work to do. The light organ has been partially prepared for the bacteria’s arrival, but the final touches won’t occur until the newly arrived bacteria get things started. It’s as though they’ve arrived in a new house but only the frame is up. The bacteria themselves have to do the finish work.