In his book Wonderful Life, the late, great paleobiologist Stephen Jay Gould argued that chance has had the single greatest influence on the history of life. He wrote about a thought experiment that he called "replaying life's tape." It was an illustration of how unlikely it would be for the biota of Earth to re-evolve in the same fashion that it has over the past almost four billion years. As I sat down to write about the species that has been my lifelong preoccupation, the longest-lived animal survivor known to science, Nautilus pompilius, better known as the Chambered Nautilus, I began to replay my own tape and see how a series of random, chance events have directed my own life and career.
For 25 years the overarching theme of my work as a paleobiologist has been a need to know the identities of which species lived, and which died, in the great mass extinctions, the five intervals in geological time, going back 540 million years to the dawn of animal life, when a majority of species were killed off. I have been able to tell a very plausible evolutionary story about how the nautilus has survived over 500 million years by side-stepping the dinosaur-killing asteroid and every other menace the earth and cosmos have thrown it. It was not because it was especially adaptable, it was because it had the incredible good fortune to prefer deep waters and a metabolism suited to life in the slow lane.
But there is one chance element that I never foresaw in my field notes. Humans—present on Earth only because the dinosaurs died out—find the nautilus, with its mother-of-pearl interior, and tiger-striped outer coloring, so beautiful, and so suitable for jewelry, that they are managing to do what mass extinctions never could: drive the nautilus to extinction. This avaricious fascination with the nautilus set the stage for the darkest day in my life in 1984, when, in the Pacific islands, I found myself trying to bring back to life the copiously bleeding body of my field assistant.
In the past few years I have contributed to the breakthrough discovery that ancient Nautilus pompilius is in fact many separate species, which has overturned the widespread reference to it as a "living fossil." Yet the human toll on the nautilus may be the last discovery that I ever make about this remarkable animal. Looking back at the myriad decisions, tests, detours, and the rest of the messy contradiction and actions that we call life, I have to marvel at the waves of chance that swept the nautilus and me into its rough seas.
My journey began with the 1954 Disney movie 20,000 Leagues Under the Sea—the first movie I ever saw on a big screen, at the ripe old age of five. The star of the show was the submarine, or rather Disney's rendering of the storied craft at the center of Jules Verne's tale: a surprising shape of curves and straight lines, an extended diamond of a ship exuding strength and speed, difficult to remember in detail beyond an inchoate vision of grace. Much of the movie took place underwater, a highly romanticized underwater at that. Growing up next to Washington state's Puget Sound, with its wonderful tide pools and salmon, whales and seabirds, was itself an invitation to love science and marine biology.
Since the nautilus first came to the attention of European naturalists in the 1600s, there was intense speculation on how it used its chambered shell to attain weightlessness. For almost four centuries it was believed that when each new chamber was formed, the animal secreted gas into it. It was the same principle, or so it was thought, used by submarines: gas pumped into ballast tanks generate buoyancy.
An archipelago located 750 miles east of Australia, New Caledonia is the only place on Earth where nautilus swim in water shallow enough for a scuba diver to see them. On dark nights, I was able to follow them in their native habitat, the first scientist to ever do so. With a tough, ex-military French buddy, I spent many nights diving outside the vast reef that parallels the Great Barrier Reef of Australia. Every night we would spend an hour stabbing through the clear water with our dive lights, our probes reaching into the blackness, illuminating the white shells of the ascending nautilus. We would follow them, on moonlit nights with our lights off, as they swam right into the surf zones of the shallowest parts of the outer barrier reef. Their forays into the shallows was to find food—not live food, we learned, but fresh molts of lobster. That was a surprise. The nautilus, it turns out, is an obligate scavenger, and can find carrion from many miles away, thanks to an exquisite olfactory system.
My trip to New Caledonia utterly changed my life. It brought me research papers, professorships, books, a marriage and a son. It would send me on quests first to Europe and then into the Caucasus Mountains of Asia Minor to further understand the cause of the event that removed ammonites from Earth, yet spared the Nautilus. It sent me to South Africa to study an even more ancient extinction, then Australia, New Zealand, South America, and Antarctica. It was more adventure than ever imaginable by that 5-year-old boy in 1955, staring wide-eyed at the giant squid being fought to a draw in the climactic scene in Disney's astonishing movie.
Chance, though, is not just the purveyor of gifts. In 1984 I was on an expedition outside New Caledonia's barrier reef, formed to study the daily migrations of the nautilus. I was accompanied by, among others, Mike Weekley, a 26-year-old marine biologist, who had worked at the Waikiki Aquarium. Mike was a veteran of nautilus research trips, seemingly fearless, and an expert diver.
On our fifth day of research, we discovered thieves approaching one of our holding cages, roped to a buoy, where ten nautiluses were being kept for future experiments. Nearby, tied to the reef edge, a long piece of rope stretched down to a deep cage, where we were performing a crucial experiment: What was the maximum depth at which the nautilus could empty its chamber?
Tragedy changes a person. The nautilus had made me a scientist. Yet that same animal caused the death of a close friend. Was his death due to chance, or the human equivalent of bad genes— and, if genes, Mike's or mine? How could it be explained? I quit studying the nautilus. In fact, I quit science altogether. In the pit of my depression, fortune intervened in the person of Gould. From his perch at Harvard, Gould had taken an abiding interest in all of us younger paleontologists, but a particular interest in my research, which showed that the ammonites disappeared suddenly after the cataclysmic asteroid, in contrast to the prior view that they went extinct gradually. Gould encouraged me to keep researching, beyond the ammonites. He helped me switch to the study of death writ large.
In 2011 and 2012 I returned to my old study sites in the Pacific, and collected DNA samples that helped confirm that Nautilus pompilius is many separate species. But I also discovered that unlike in the deep past, perhaps only a few thousand individuals make up each species. A few thousand individuals swimming long distances to be caught in a baited trap, from which they are hauled to the surface, killed and sold for $1 a shell. For buttons and cheap tourist jewelry.
It is a horrid irony. Although the nautilus ruled the oceans for hundreds of millions of years, Earth's changing conditions dwindled the number of species, about three million years ago, to less than a handful—or even a single species. Then came the advent of the Ice Ages and a radical drop in global sea level and temperatures, which, combined, created cool, highly oxygenated oceanic conditions similar to those when hundreds of nautiloid species existed. The nautilus was making a huge comeback in diversity, to the point where it may have been poised to once again be a presence in every ocean, rather than its current confinement to the western tropical Pacific.
But as recently as 50 years ago, the comeback hit a roadblock: us. In the Philippines and probably in Indonesia, the distant nautilus species are being harvested to extinction. An even greater crime is occurring in Papua New Guinea and Indonesia, the only two places where Allonautilus, a new genus defined by Saunders and me, are found. Shells of Allonautilus can fetch more than $500. While the shells of more common nautilus are far less expensive on eBay (a large shell goes for about $40), the slaughter is severe. Between 2007 and 2010, the United States Department of Fish and Wildlife discovered that more than half a million nautilus shells or artifacts were imported into the United States alone. Fleets of nautilus boats now scour the coastlines of the South China Sea.
This is not a death I can escape from, nor want to. Today I continue to travel to the Pacific islands to compile data to raise awareness about just how rare the nautilus has become. My work has been partly supported by two remarkable fundraisers, Josiah Utsch, 12, and Ridgely Kelly, 11, of Maine, who launched a Web site, Save the Nautilus, after reading a New York Times article, "Loving the Chambered Nautilus to Death," by science journalist William Broad. They collect money, usually $1 at a time, from school kids, and so far have raised over $10,000.