Pick from the Past
Natural History, November 1999

Undertakers of the Deep

An organic windfall, the body of a dead whale on the seafloor
attracts an array of attendants—even years after the flesh is gone.




Full fathom five thy father lies;
     Of his bones are coral made;
Those are pearls that were his eyes:
     Nothing of him that doth fade,
But doth suffer a sea-change
Into something rich and strange.

         —Shakespeare,
The Tempest

“I want to show you a grave,” intones the scientist, “one hidden at the bottom of the sea.” Sitting like headstones, the white skull, ribs, and vertebrae are spaced just inches apart. But something of their outline speaks of a leviathan.

“That skeleton was once a whale,” explains oceanographer Craig Smith, of the University of Hawaii: School of Earth & Ocean Science & Technology. The lanky, fortyish Smith, graduate students Amy Baco and Amanda Jones, and I are reviewing videotape of an undersea journey taken earlier in the day to the murky depths of the San Diego Trough, a Pacific Ocean basin some twenty miles off the southern California coast.
Scavengers can devour the bulk of a carcass in less than six months. Feeding on the flesh and blubber of a gray whale are a Pacific sleeper shark, a grenadier fish, hundreds of orifice invading hag-fish (blue), large Paralomis crabs, and swarms of amphipods (inset).

Scavengers can devour the bulk of a carcass in less than six months. Feeding on the flesh and blubber of a gray whale are a Pacific sleeper shark, a grenadier fish, hundreds of orifice invading hag-fish (blue), large Paralomis crabs, and swarms of amphipods (inset).
This is the first evening of a June 1998 research cruise aboard the 274-foot research vessel Atlantis, operated by the Woods Hole Oceanographic Institution in Massachusetts. Gathered in the vessel’s video and computer room, we gently rock to and fro as the videotape player whirrs. Atlantis is the mother ship of the deep-diving submersible Alvin, which carries three passengers to depths of almost 15,000 feet.

Alvin’s perfectly round inner sphere, made of titanium, has so many switches and gauges that it looks like an airplane cockpit. Three viewing ports, each only four inches wide, sit low on the front curve of the orb. Covering it is Alvin’s white hull, topped by a bright orange conning tower, or entryway, through which a pilot and two scientists crawl to reach the inside of the titanium ball. The chamber’s hull is all that separates the sub’s passengers from the crushing pressures of the deep sea.

Alvin is about to ferry scientists and sub pilots on six scheduled dives—one per day—to whale graveyards in the Pacific. After each day’s dive, the researchers, especially Smith, the expedition’s chief scientist, will get a second look at that day’s graveyard, provided by videotape cameras mounted on Alvin’s hull.

More than a decade ago, Smith made a serendipitous and far-reaching discovery. At the bottom of the Santa Catalina Basin, some thirty-five miles off the California coast and some 4,000 feet beneath the ocean’s surface, he found evidence of life after death. On an Alvin dive during which the sub hovered just above the dark, silty bottom, scientists aboard suddenly glimpsed rows of large white clams like those found living near deep-sea hot springs or hydrothermal vents. But here there were no vents.

Near the clam colony was the outline of a huge creature, barely visible through the mud stirred up by Alvin's approach. As the cloud of particles settled, the researchers peered out at the giant vertebrae, ribs, and skull of a seventy-foot-long cetacean. Because of its great length, Smith believes it was either a blue or a fin whale. He had unwittingly found a clue to a mystery puzzling ocean scientists since hydrothermal vents were discovered a decade earlier on another Alvin dive: How do the larvae of animals permanently attached to the vents spread from one widely separated deep-sea vent system to another, hundreds of miles away? One possible answer, Smith learned, is “on sulfide-rich decomposing whale bones, which the larvae might use as stepping-stones to new vents.”

In 1977 researchers found that hydrothermal vents support animal life thousands of feet below the ocean’s surface. These creatures derive energy not from plants growing in sunlit surface waters but from bacteria feasting on chemicals spewed from the vents, a process called chemoautotrophy. Giant clams, tube worms,
Bacteria and any bits of flesh clinging to bones or decaying in nearby sediment sustain grenadier fish; Paralomis crabs; smaller lobsterlike galatheid crabs; and a dense carpet of minute white polychaete worms. Thirty months after the whale fall reaches the seafloor, only the skeleton remains.

Bacteria and any bits of flesh clinging to bones or decaying in nearby sediment sustain grenadier fish; Paralomis crabs; smaller lobsterlike galatheid crabs; and a dense carpet of minute white polychaete worms. Thirty months after the whale fall reaches the seafloor, only the skeleton remains.
and mussels were also later found in other, similar habitats: cold seeps, where chilly, methane-rich or sulfide-rich water emerges from the seafloor, and hydrocarbon seeps, where petroleum oozes from sediments. The animals in chemoautotrophic-based communities also have been found in a sunken ship that contained cargo rich in organic materials. “It appears that a common factor in all these habitats is the presence of sulfides,” explains Smith, “upon which chemoautotrophic bacteria—the base of this food web—are feeding.”

But these habitats can be ephemeral. According to Smith, some may last only ten years, and when they fade away, the life that depends on them also disappears. Considering the great distances from one of these deep-sea “islands” to another and the cold, lightless environment in between, researchers wondered how the larvae of vent and seep creatures moved from one site to another.

In 1987, when Smith inspected the whale bones that Alvin had just brought to the surface, he noticed that they were encrusted with several species found at sulfide-rich hydrothermal vents and cold seeps. A dead whale’s body sinks to the seafloor, where much of it, he discovered, decomposes anaerobically to produce sulfides, which infiltrate the nearby sediment. Sulfide-rich whale bones could thus serve as possible way stations between vent and seep habitats, allowing the larvae of chemoautotrophic animals to spread across the vast ocean floor with the help of remains spaced many miles apart.

Six years later, Smith hit a jackpot of sorts when a lost Titan missile led the U.S. Navy to a site near southern California's San Nicolas Island. Using sonar in an attempt to locate the missile, the Navy instead found the outlines of eight whale carcasses and reported them to Smith. Recently, in a quest for even more bones, Smith got permission to retrieve carcasses of dead whales that wash ashore and to haul them back out to sea. He hitches them to a boat, tows them seaward, attaches ballast to their tails to make them sink, then cuts them loose above great depths like those of the San Diego Trough and Santa Cruz Basin. “Actually, his accomplices sometimes do this part,” jokes partner-in-crime Dale Stokes, of the Scripps Institution of Oceanography in La Jolla, California, a participant in this week's cruise. One of these adventures, he continues, took place “when a whale washed up on the Silver Strand of San Diego.” The residents were desperate because the carcass smelled so bad and was right outside their front doors. Since Smith was in Hawaii, Stokes relates, “he sent me and another assistant out to package it up, so to speak, and tow it out to sea with a chartered boat. It was so heavy that it took us eleven hours to get it out far enough to drop over deep waters.”

Expeditions to whale grave sites, both natural and those that Smith has had a hand in creating, have led to new speculations on the possible importance of these remains of life in the deep sea. On this cruise, he and his colleagues hope to test their ideas-hypotheses about the succession of creatures that colonize the bones of sunken whales, the role of “whale falls” as havens for chemoautotrophic creatures, and the way deep-sea animals respond to local infusions of organic material. Whale bones, Smith maintains, “are the largest natural sources of such organic enrichment in the deep. How the fauna there makes use of them will likely give us insights into how it would react to something like deep-sea relocation of sewage sludge, for example. This is information we will increasingly need as the deep ocean is looked at as a possible disposal site for all kinds of materials.”

All kinds of materials, indeed. On the second evening of the cruise, I look out to gray skies and grayer waters: the Pacific in June, overcast but with mercifully calm seas. As Atlantis rocks back and forth, I wonder what it would be like to be buried at sea. I picture my body at rest, forever undisturbed in some kind of undersea kingdom.

I voice this notion to Smith, who’s walking by on his way to prepare Alvin for the next day’s dive. “Burial at sea is actually the quickest way on earth to be recycled,” he cautions. “The undertakers of the deep—the parade of animals that show up at large food falls, like whale and other bodies—see to that.” Picturing sharks, I shiver. “Sharks are the least of the problems,” adds Bryce Glaser, Smith’s technician, who’s working side by side with Smith on an array of bone- and sediment-sampling devices on the sub’s front end. “It’s actually the smaller, slithering, creeping things that finish you off.”

When whale bodies first sink to the ocean floor, explains Smith, they are reduced to skeletons by scavengers such as hagfishes, which are primitive, eel-like fishes of the depths. “That can take as little as four months and is the first stage in a succession of species that feast on the whale.” Once the scavengers quit the scene, second-stage creatures, like polychaete worms
Fissured bone decomposes to produce sulfides that permeate the seabed, providing chemoautotrophic creatures (which thrive on energy from inorganic compounds) wih nourishment for years. Here bones and sediment are crowded with Idas mussels (golden);Cocculina limpets (violet with white polychaete worm tubes atop the shells); gatheid crabs; hundreds of live and dead vesicomyid clams; white, hairlike bacterial mats; and the marine snail Astyris.

Fissured bone decomposes to produce sulfides that permeate the seabed, providing chemoautotrophic creatures (which thrive on energy from inorganic compounds) wih nourishment for years. Here bones and sediment are crowded with Idas mussels (golden);Cocculina limpets (violet with white polychaete worm tubes atop the shells); gatheid crabs; hundreds of live and dead vesicomyid clams; white, hairlike bacterial mats; and the marine snail Astyris.
and crabs, move in for some four to thirty months. They dine on fleshy particles that have wafted from the carcass onto the seafloor, and perhaps also feed on bacteria. Within three to six feet of whale remains, half-inch-long polychaetes can reach densities of 2,000 per square foot. After this stage, little is left but bones. Whale bones contain rich oils that bacteria-the cleanup crew-then further decompose, forming sulfides and other compounds in the process. This third and last lineup includes not only bacteria but also certain species of worms, clams, and mussels, some of which harbor chemoautotrophic bacteria in their bodies. With the help of these bacteria, the third-stage creatures are able to make use of the sulfide-rich compounds in whale bones. Animals that live on the bones are both varied and numerous. When Smith and Amy Baco brought up vertebrae from one whale fall off the California coast, they found 5,098 animals, representing 178 species, on little more than one square yard of bone. Such communities can survive for years: the assemblage of creatures Smith discovered in 1987 at the bottom of the Santa Catalina Basin was still going strong in 1995.

At 8:00 a.m. on our third morning at sea, the ship's positioning thrusters suddenly rev up, announcing that Alvin is ready to come out of its “hangar” and inch along a cog railway leading to the ship's stern. At the end of this railway, the sub will be lifted off the ship via a massive pivoting A-frame crane and gently set down on the surface of the sea. On today's dive are Baco and Frederic Martini, a University of Hawaii expert on hagfishes. Along with the sub's pilot, Steve Faluotico, they will try to locate a gray whale sunk by Smith just six weeks ago in the Santa Cruz Basin. “From GPS coordinates,” Baco explains, “we know approximately where to look for the carcass, but we may have to roam around a bit to find the exact site.”

As we would later see on videotape, Baco and Martini don't locate their quarry until late morning, when the sub has reached a depth of more than 5,000 feet. Finally, off in the distance, Baco spots white ropes snaking into darkness—the lines used to tow the whale out to sea. Undulating in slow motion just inches from the carcass is a grenadier, a deep-sea “rattail” fish with huge, dark eyes, the better to see its prey-or a carcass-with.

Alvin kicks up muck from the bottom, and a constellation of silty particles surrounds the whale, temporarily obscuring its form. Then the tempest clears, and a mass of white blubber appears. A boon for Martini, hagfish are everywhere, their twirling, elongated bodies attempting to slither into every possible crevice in the whale blubber. “That may be where the mythical Medusa idea originated,” he comments, “from an early view of a drowned body, with hagfish protruding from every orifice.”

Alvin hovers near the whale for several hours as the scientists collect blubber and sediment samples. Then the submersible pulls away and begins the climb to the surface. The whale once again lies in darkness, invisible to all eyes but those of the creatures of the Santa Cruz Basin.

Back down the sub goes, day after day. On one dive, Alvin returns to the burial ground of a dead whale released by Smith above the San Diego Trough in June 1996. The sub nears the grave site, but there’s little left of life except a jumble of bones-or so it seems at first. At dive’s end, bone and surrounding sediment samples are unloaded, carefully carried into the lab, and sifted. The dark particles contain a profusion of living organisms. “Several clams and worms characteristic of whale falls live in the enriched sediment near the bones rather than on the bones themselves,” explains Smith. “Sometimes we’re lucky enough to get a fair number of them in a sediment sample.”

My nose leads me to the ribs and vertebrae. Reeking of sulfur and softened by long exposure to water, the bones are catalogued and photographed. I’m soon handed a pair of forceps and put to work on one of four vertebrae, painstakingly picking off hundreds of translucent, quarter-inch-long mussels called Idas washingtonia. “Idas is a member of the third-stage animal community, the one that lives off sulfides emitted by the decomposing bones,” Smith explains. The mussels, which look like nothing so much as miniature fingernails, will be preserved for later genetic comparison with other mussels of the same species from different whale-fall sites. The mussels share space on the bones with animals that Smith discovered (and that now bear his name): a limpet named Cocculina craigsmithi and a polychaete worm called Harmothoe craigsmithi.

Later that night, when the sun has nearly set and the scientists have started a second shift of bone picking, I make my way up several steep flights of stairs to the bridge. Looking out to sea from behind a panorama of glass windows, I spot a pod of fin whales off in the distance. Were I outside, I think, the only sounds would be the sighs of the whales as they break the surface. By our final night at sea, I realize I’ve come full circle. Bypassing a certain horror about what happens to a body in the depths of the ocean, I now have the feeling that burial at sea is maybe not so terrible a way to be recycled.

Beyond providing an understanding of these ocean oases and determining how the denizens of the depths respond to large windfalls of organic material, Smith’s research documents how, in death, one creature can sustain the lives of many others. It’s a celebration of a sea change-from whales to hagfishes and crabs, to worms and mollusks, to chemoautotrophic creatures that will never see the light of day.

In her many articles on sea life, writer Cheryl Lyn Dybas has combined her education in oceanography and marine policy with her love of boating and diving. A memorable moment during her week aboard the Atlantis came when the ship had to swerve to miss hitting a live whale. A rare event the crew found particularly eerie, given their mission of visiting cetacean graveyards. A resident of Falls Church, Virginia, Dybas has contributed to the Washington Post, Smithsonian, Wildlife Conservation, Adirondack Life, Yankee, and other publications. Painter Michael Rothman enjoys accompanying scientists in the field and has traveled as an illustrator to Puerto Rico, Samoa, French Guiana, and Brazilian Amazonia. For the whale article, Rothman and an American Museum of Natural History mammalogist reconstructed a gray whale from the actual bones. Rothman studied fine arts, painting, and botanical illustration in New York City. His work has appeared in various magazines, in the New York Times, and in books, including Inside the Amazing Amazon (text by Don Lessem, Crown, 1995) and Nafanua: Saving the Samoan Rain Forest (text by Paul Alan Cox, W. H. Freeman, 1999).

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