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By Virginia Morell
"OK, there it is our mystery mollusk." Bruce Robison leans in toward his color monitor. A ghostly creature resembling a cross between a megaphone and Thing, the Addams Family pet hand, floats on the screen. The soft, oval lips of its megaphone roll in and out, while the hand waves up and down, slowly and rhythmically.
The animal does not in the least resemble an earthly mollusk—an organism like a snail, oyster, or mussel with a firm shell protecting its soft body and that travels, if it must, on a single, podlike foot. This one is swimming free in the deep, dark waters of Monterey Canyon off California, more than a mile down, although the word "swimming" doesn't quite capture the creature's ethereal, yoga-like moves.
For a long moment it is quiet in the control room of Western Flyer, the state-of-the-art research vessel of the Monterey Bay Aquarium Research Institute, where Robison, a bearded, graying Neptune, reigns as chief scientist. Next to the captain his word is law here, and he's seldom without something to say. But he now sits silently with his fellow oceanographers, peering at the mollusk's image on Flyer's bank of color monitors. There's only the sighing sound of the ocean heaving against the ship and, like a soft echo, the sound of the scientists' breathing.
Robison is the first to break. "How the hell does this animal work?" His question, asked with delight and frustration, illustrates how little is known about life in the ocean's deepest waters—even these waters about 60 miles offshore.
Robison's view of the beast, as he affectionately refers to this as yet unnamed species, comes from cameras mounted on a submersible vehicle named Tiburon, connected to Flyer via a data-transmitting cable. Equipped with a special buoyancy system and stuffed with high-tech gear, Tiburon can float quietly beside any animal and transmit real-time video of its every move to the scientists aboard the mother ship.
The beast bends and folds with the grace of a ballet dancer. Somehow its strange choreography must indicate how it lives, hunts, and reproduces. But none of its movements make sense to those of us from terra firma.
"We've caught a few of these in the past couple of years, but we still don't understand how they use all their parts or what they eat." Robison addresses the beast: "What do you catch? And how do you do it?"
"Must be something slow and stupid," suggests one of the scientists. "The beast's not exactly built for speed."
Robison chuckles in agreement. "Nope. But he's a predator, like everybody else down here. Maybe he eats eggs?"
Robison is certain that he will find the answers—if not on this dive, then perhaps the next. After all, this is only the eighth of these animals that Robison has ever observed.
His confidence stems from the richness of Monterey Bay and from the combined capabilities of the 117-foot Flyer and its robot submersible. Together the vessels are giving scientists their first glimpses of some of the deepest parts of Monterey Canyon.
Hidden by the ocean's waters, the canyon begins a few yards off the California coastline. It descends gradually, eventually extending a hundred miles into the Pacific; water depths reach more than two miles in places. The canyon's network of valleys is as bountiful as a rain forest. Sea stars, anemones, and corals encrust its terraced precipices. Fish, crustaceans, jellies, mollusks, squid, and octopuses navigate its dark waters. Colonies of clams, tube worms, and uncounted varieties of bacteria ooze from its cold seeps.
Over the past four years, Robison and his team have made nine expeditions to the lower reaches of the canyon—a zone of frigid waters where sunlight never shines, a world of little oxygen and great pressure—finding new animals and puzzling out their behaviors on nearly every trip. "It's a world so unlike our own that we really shouldn't be surprised to find animals that defy our imagination," says Robison, finally peeling his eyes from the mystery mollusk on his screen. "The deep sea is the largest habitat on our planet, and yet it's still the most unexplored. That's why every time we come out here, we're almost guaranteed to find something new. We're like 19th-century explorers, out here in a world no one has seen before."
The team members aren't just trying to bag new oddities from the sea; they're seeking to understand the canyon's overall deepwater ecology and the natural history of the animals they encounter. "There are animals down here that scientists know about because they've caught them in their trawling nets," Robison says. "But no one has seen them swim, feed, or reproduce. Now look at us. We're filming every move this guy makes. We'll be able to study that later and try to make some sense of him."
Just then an inch-long, white butt worm (so-named because of its resemblance to a cigarette butt) drifts into view. Instantly Robison's colleagues break into an eager and lusty chorus: "Eat it! Eat it! Eat the butt worm!"
But the mystery mollusk does not. No tentacle shoots out. No poisoned dart is launched to grab what other residents of the deep—and apparently some of Flyer's scientists—regard as a tasty meal. The beast merely continues its curious undulations, oblivious to the creatures from above who so hungrily monitor its every move.
Scientists began an earnest exploration of deep-ocean marine life in 1872 when the British government sent H.M.S. Challenger on a three-and-a-half-year voyage around the world with a charter to discover what lurked in the waters below. As implausible as it may seem today, researchers then generally deemed the deep-sea environment little more than a watery desert, too harsh to support life. Many were thus astonished when, after dragging her nets from ocean to ocean and dredging the seafloor, Challenger returned stuffed to her gunwales with more than 4,000 new species. There were bizarrely shaped sea stars and worms, fantastic crabs and fishes, including anglerfish from whose forehead sprouted a stalk with a dangling, bioluminescent lure. Spurred by Challenger's biological trove, other researchers began dragging and dredging to search the seas for exotica.
"And that's what people did for about a hundred years," Robison says early the morning after we saw the mystery mollusk, as we watch the ship's crew prepare Tiburon for another dive. "We used to bring up all kinds of dead and beaten-up animals, little bits of white goo and jelly stuck to the nets. We had no idea what they were, although there were tantalizing hints. Things like, 'Wow! This piece of Jell-O caught this fish! How did it do that?'"
Other pieces of Jell-O were "breathtakingly beautiful," Robison recalls, "like holding a bit of rainbow in my hand or discovering a feather without ever having seen a bird. What kind of forest ecologist would settle for that?"
Robison found a way into the ocean's forest via submersibles, first with a manned expedition and later using remotely operated vehicles (ROVs) like Tiburon and its older sibling, Ventana. With their video and still cameras, remote sensing gear, and collecting equipment, ROVs can gather enormous amounts of data.
Robison says he used to tell people what he saw on the manned submersible dives. "No one believed me," he laughs. "Now I show them the photographs—and sometimes the specimen."
Below us Tiburon, yellow and blue, and about the size of a small SUV, sits tethered in Flyer's center hull. Two of the crew give the ROV a final check before its dive, and Robison ducks into the control room to man his station. An operator seated at a crane above the submersible lifts the vehicle from the ship's floor. The hinged floor opens, revealing a sloshing square of turquoise. He positions Tiburon above the square. It dangles there, swinging in time with the rhythm of the ship and the sea.
"We're ready for release," says ROV pilot David French, radioing to the control room.
"Any time then," the word comes back. A moment later Tiburon splashes into the water and quickly disappears.
All action is now in the control room, dark except for the images on the monitors and the flickering lights on the control panels. Paul Tucker, Tiburon's pilot for the morning shift, sits a few feet away from Robison in a Star Trek-style command seat, his hand firmly on controls much like those of a video game. It's Tucker's job to "fly" Tiburon (as the scientists say) and direct its collecting devices if the scientists spot an animal they want to bring to the surface. Robison sits in a similar seat, with a screen directly in front of him and a separate control box for the cameras, focusing and zooming in on whatever he finds interesting.
Tiburon sinks through the first few hundred feet of ocean within five minutes. The light in this narrow band of water provides enough energy for tiny plants of phytoplankton to grow. Nearly all life farther down depends, directly or indirectly, on the phytoplankton in these upper waters, where insect-like copepods and krill feed on it like deer grazing in the forest. The copepods and krill, in turn, are fodder for a large variety of predators that lurk in the darker midwaters where light is minimal—and where plants, consequently, never grow. "Most of the animals we'll see in midwater are predators," says Robison. "It's a dog-eat-dog world down here."
Tiburon continues dropping through the jade world of the surface waters. The ocean grades into a richer turquoise and then a royal blue, which gradually grows inkier as the ROV flies into the unknown. The submersible's cameras look out on a world illuminated by the merest hint of sunlight; only Tiburon's strong underwater lights, which cast a glow close to that of daylight, allow us to see anything. And initially most of that anything appears to be dandruff.
"That's marine snow—or, less politely, sea snot," says Steven Haddock, a specialist on bioluminescent jellies. "It's a lot of organic material: bits of dead animals, plant cells, fecal pellets."
The ocean's garbage, in other words. But it is pretty garbage: a dense snow of white flakes falling and swirling in an indigo world. And it's important garbage, as Robison explains.
"We've always been surprised by how much life is found on the ocean's floor," he says. "What provides the sustenance for it? Some of it is this detritus, this constant organic rain, but a lot of it, I think, is from the discarded filter houses of some animals we should see pretty soon."
In the next instant, as if on cue, Tucker homes in on a giant larvacean, Bathochordaeus charon—which, despite its long name, is the size of a tadpole. Larvaceans, using mucus extruded from glands inside their bodies, spin nets to trap food particles much as spiders spin webs to trap insects. Some of these nets, or filter houses as the scientists call them, extend more than six feet.
"Good, he's home," says Robison, moving a lever on his control panel to zoom in on the animal, and filling the monitors with its image.
Inside the large house of mucus is a smaller, butterfly-shaped structure the larvacean has also built: its feeding filter. And inside of that, fluttering like a moth, is the larvacean itself, a flat, transparent ribbon of a being. Its tail beats a steady pulse that pumps water, particles, and microscopic plankton through the filters, leaving the choicest bits for the larvacean to gobble. When the mucus threads of its home get too gummed up with food, Bathochordaeus simply swims away, then builds a new house. "We think their discarded houses take a lot of organic matter to the floor, the benthic zone," says Robison. "Just look at how gummed up this one is. Yummy!
"We'd love to see one leave its old house and start in on a new one," adds Robison. "We've tried many times to keep these guys alive in our lab, but they're so fragile, they just don't last long enough."
The liquid world of the midwater zone has no corners or walls, so many animals here that lack shells, including larvaceans, are safe from the damaging effects of bumping into hard surfaces. But aquariums are altogether different. Although researchers contain such animals in large aquariums with circulation systems designed to keep them away from the walls, inevitably there are collisions, and the larvaceans die.
We watch the larvacean flutter inside its house a while longer. Small white particles are stuck along all the filaments. Then Robison tells Tucker to bring it in. Robison has a new aquarium at the institute and hopes that this time the larvacean will survive and surrender its home-building secrets.
Pushing various buttons on his control panel, Tucker moves the submersible's swing arm to position a wide-mouthed jar directly below the animal. He maneuvers the vessel upward to surround and capture the larvacean.
The press of another button closes the lid. We're down to 650 feet now. We can see only what the cameras see, and while they are angled to give a 270-degree view, the view is still much like peering at the ocean with one eye through a pipe, as Robison puts it. He leans forward, biting his lower lip, watching the snow fall, as thick as a blizzard now. At this depth we are just below the photic zone, a level reached by barely one percent of the sunlight that touches the ocean's surface.
"All stop!" Robison barks. "Holy smokes! How long has it been since we've seen one of these?"
He focuses the camera's lens on what first appears to be a large, white blob. But as it comes into view, the blob assumes the shape of a leaf with an elephant-like trunk.
"It looks like a confused mess," says Tucker.
"Well, it's a heteropod—a snail," says Robison, "but its shell has been greatly reduced." He points to a thin white bar at the base of the "leaf." "That's all that's left of it."
Although closely related, this swimming snail looks nothing like its terrestrial cousins. Animals in the midwater column need to be neutrally buoyant, and so this heteropod's shell has nearly disappeared, and its single foot has grown into a muscular swimming fin. Two large eyes project on small filaments from either side of the snail's trunk-like head. (Despite the almost complete absence of sunlight, many animals in these depths still have eyes and use them in the faint light to spot their prey, often zooplankton, and to watch for predators.) Tucker catches the snail, using the submersible's suction nozzle to gather it into a jar, then guides Tiburon farther down.
The other four scientists in the control room grow more attentive with every foot Tiburon drops. Are they expecting something? "Between 200 and 700 meters [650 and 2,300 feet] is biologically the richest part of the midwater column," Haddock explains. "This is where we're going to get some good animals."
It's a forbidding region for landlubbers like us—40°F, oxygen poor, crushingly deep—but not for the creatures that call it home. At first I see nothing but the snow, but as I follow the scientists' eyes I'm able to pick out what they see and realize that there are animals everywhere: tiny oval jellyfish trailing long tentacles like kite tails; a caterpillar-like polychaete that shimmers blue and purple ("Hey, it's Elvis," the scientists joke). There's a jelly shaped like an angel's halo and another so transparent we can see in its gut the orange krill that it had for breakfast.
We watch a siphonophore, a creature that seems to be not much more than an unraveling rope with a string of stomachs and tentacles attached, and radiolarians—colonial, amoeba like animals that join together in sets of eight to build Buckminster Fullertype houses of brittle silicate strands. Dark squid rocket by, while silver hake wriggle into the glow of Tiburon's lights. There are dozens of larvaceans and empty larvacean houses, so covered with chunky flakes of marine snow, bacteria, and other detritus that they look like yesterday's onion rings. Without their makers inside to keep them aloft, and weighed down by all the organic matter, they sink like collapsed parachutes.
Nearly every creature we see at this depth—fish, squid, invertebrates—is bioluminescent, equipped with special organs called photophores that emit light via chemical reactions. Most of the animals produce the light themselves with special proteins, but others rely on luminescent bacteria that live inside their photophores for their otherworldly glow. Some jellyfish acquire their lights only by eating other luminous species. Scientists remain unsure as to why so many deep-ocean species need to shine, but since nearly 90 percent of the animals here can do so, there must be a strong advantage.
"The standard hypothesis is that the light frightens away predators, but some use it to attract prey or send signals to potential mates," says Haddock. "Others use it to hide."
Hiding is key to surviving in this predaceous world. But it's tricky to hide in what amounts to pure open space. One technique is to be transparent like the larvaceans and many other gelatinous animals. But that doesn't work for species with more body mass, such as squid and fish. Several of these species have devised ways to hide behind their bioluminescence—although using lights to hide in the dark seems like something only a fool would try. When we see a cockatoo squid, Haddock shows how this optical trickery works.
As this squid's name suggests, it looks like a cockatoo, with its tentacles gathered in a feathery, crest like fashion. The squid appears white to us although its body is mostly transparent, protecting it from visual predators in the depths. The squid's eyes, however, are opaque. "Predators often come at their prey from below," says Haddock, "and the opaque parts of animals higher up in the water column cast a silhouette that can alert hungry fish."
To erase these shadows, the cockatoo squid has evolved U-shaped photophores at the base of its eyes. The photophores emit a blue glow that effectively cancels the squid's eye shadows. Lanternfish are similarly equipped, with a row of blue-light-emitting photophores along their bellies to hide them from a predator's fangs.
"What do you know?" Robison suddenly exclaims. "It's Vampyroteuthis!"
On the screen, a dark, bat-like creature with eight arms and iridescent eyes the size of marbles flaps slowly in the glare of Tiburon's lights. A living fossil, Vampyroteuthis is the last representative of a lineage of animals that may have given rise to modern-day octopuses and squid. Since Robison typically spots one of these rare, archaic animals only once a year, he settles in to watch and film it.
"There are so many things about it that we don't know: What it eats, how it generates the bioluminescence on the tips of its arms, or what these extra tendrils are for," he says, pointing to two long, trailing filaments. The animal can coil these up in two pockets between its third and fourth arms. But unlike its other eight arms, these two lack suckers. "I don't have any evidence, but I think it uses them as chemical sensors," says Robison. "The deeper we go, the darker the ocean gets. Senses other than sight become more important."
After Tucker collects the Vampyroteuthis, David French replaces him at the controls. We fly down steadily, reaching a mile below the ocean's surface, then a mile and a half. The marine snow continues to fall, but it's sparser now, and there are few animals about.
"This is the hardest place in the water column to make a living," says Haddock. "Very little food gets to these depths, so the animals you do see tend to be large and rare."
It is here that the team has found a new jellyfish, one twice as large as a family-size pizza. They've named it granrojo, Spanish for "big red." Robison hopes to see more of them on this trip, but they elude him.
"This is really an opportunistic science," he shrugs. "You make a dive and take what you get. What we see varies from year to year and season to season. But even that is important—it tells us there are cycles to these animals' lives and gives us another puzzle to solve."
A few moments later French announces, "Bottom contact on sonar." The seafloor rolls out like a soft, beige carpet. Robison points to tiny purple jellies floating just above the floor. Beyond them, lying on the floor itself, are several bumpy sea cucumbers, sea stars with skinny legs, pink anemones, and tube worms, which quickly retract their feathery feeding arms at Tiburon's approach. A single rattail fish hangs inches above the bottom, shoving its snout into the sediments in search of a meal.
"Very few people," Robison says softly, "have ever seen this part of Earth before."
We crowd around peering at the screens, wishing for a larger view, wondering what mysteries lie beyond the lights of Tiburon.
Robison heaves a sigh. "Time's up," he says. Tiburon has been submerged for about nine hours. "Let's head for the top."
Three hours later the submersible emerges from the water. The scientists dash for their collecting jars, rushing to place their new animals in cold rooms and aquariums—hoping that some will live a few hours, days, or even months longer, to tell us more about what they are and how they exist two miles down in the land of marine snow.