This article was originally published in bioGraphic, an independent nature and conservation journal supported by the California Academy of Sciences. The nautilus inhabited the deep waters surrounding the forest-clad Manus Island, a wonderland at the northwest tip of Papua New Guinea’s Bismarck Archipelago. It lived slowly and in near-total darkness—its large eyes tuned to the blue wavelengths of bioluminescent bacteria that signal a carcass to scavenge, and it was sensitive enough to distinguish night from day 300 meters below the surface. Its 90 tentacles and excellent sense of smell helped it search for food on the sea floor. And as it grew, it added new chambers to its spiral shell. When the nautilus died—perhaps 20 or 30 years old—its soft, squid-like body rotted away. His shell lost the neutral buoyancy that allowed him to effortlessly travel to any depth he chose and float to the surface. The currents washed it into the mangroves, or onto one of Manus’ palm-fringed beaches, or perhaps onto a nearby coral atoll called Ndrova Island. Wherever it landed, the sleek cream swirl of the shell with rust-brown stripes would catch the woman’s eye as she gleaned for shellfish. She took it home with her, made it useful. Manuai Matawai grew up watching his mother, like the other women in his fishing village, use the sealed outer chamber of the nautilus shell as a ladle to separate the fragrant coconut oil from the starch of the fruit at the bottom of her pot. The nautilus – called kalopeu in the local language of the Titans – was also the symbol of a Matawai prophet he followed. But like most in his coastal community, he had never seen a live one, preferring the cold, dark depths. Then, in 2015, he got his chance. Researchers from Australia and the United States came to study the creature and Matawai, then working for the Nature Conservancy (TNC), helped organize their expedition to Ndrova. Peter Ward, a paleobiologist at the University of Washington popularly known as “Professor Nautilus,” had last visited in 1984, when he and a colleague were among the first people to examine a living fuzzy nautilus, a species belonging to a new genus. later named Allonautilus scrobiculatus. Ward and his colleagues had returned to see if the obscure nautilus and the better-known chambered nautilus (Nautilus pompilius) were still there and to try out some new research tools. From left, Pomat Kanawi, Gregory Barord, Peter Ward and Manuai Matawai snorkel off Ndrova Island, Papua New Guinea, in search of the poorly understood and rarely seen nautilus. Manuai Matawai photo Only a few scientists study nautiluses, and many of the most basic questions about the creatures’ lives remain unresolved. And yet, they have fascinated humans for centuries, their shape inspiring art, architecture and mathematics in many cultures. The submarine in 20,000 Leagues Under the Sea was called the Nautilus, as was the first nuclear submarine. Today, many companies, from wineries to fitness equipment manufacturers, also use the name. “I don’t know if it’s the most mysterious animal known or the most mysterious animal known,” says Gregory Barord, who joined the 2015 expedition led by Ward. Scientists hoped to dispel some of this mystery through their research at Ndrova – but what they found sparked even more questions. Shortly after Ward picked up his scuba gear and descended the steep reefs, he noticed the change. In 1984, scientists were lured by sharks. “They were ugly, naughty little bastards, so I was afraid to go through it again,” Ward recalled. But this time, they didn’t see a single one, indicating a change in the ecosystem. There were also signs of coral bleaching and the waters that had been pleasantly cool below the shallows now felt uncomfortably warm. The experience inspired Ward to pursue a new line of research, analyzing the composition of nautilus shells to track deep-sea climbing temperatures and looking to nautilus behavior to predict how those changes might affect their loved ones. Climate change is dramatically altering ocean life around the world, and extreme heat is now normal in many places. Ward believes the nautiluses may already be seeking refuge in cooler, deeper waters to cope. But there’s only so far molluscs can swim. Below 800 meters, the pressure is enough to explode their shells. A shop in the Philippines sells piles of spiral nautilus shells from a large bin. More than 100,000 nautilus shells were imported into the United States alone between 2005 and 2014. Photo by Greg Barord At the same time, human desire for the animals’ beautiful pearly shell has led to overfishing in some parts of their tropical Pacific home. “It’s the nautilus’ bad luck that it has this beautiful symmetry,” says Ward. Their shells can fetch US$1,000 on eBay. Between 2005 and 2014, trade data collected by the US Fish and Wildlife Service showed that more than 100,000 whole nautilus shells and 800,000 parts were imported into the United States alone. Some once-abundant populations in the Philippines—where nautiluses are also occasionally hunted for food—may already be extinct. As climate change looms, so do the nautiluses one question among all that remains: can they survive us? Nautilus have certainly always been survivors. Ancient and cunning, their lineage was adaptable enough to persevere through all five major extinction events of Earth’s past. Their ancestors, the nautiloids, appeared half a billion years ago. They were the first cephalopods, a group of molluscs that today includes octopuses, cuttlefish and squid. Back then, most life crawled along the sea floor, but nautiloids were able to float suspended in water—a key innovation they achieved by removing fluid from their internal chambers to match the density of the seawater around them, making them essentially weightless. Early nautiloids had straight, conical shells, but soon evolved the convoluted spiral with interconnected internal chambers seen in nautiluses today. In their current incarnation, they have traveled the oceans for at least 100 million years. In this shape they surpassed the asteroid that ended the age of the dinosaurs. Debris from the impact and ash from the ensuing fires blocked out the sun for two years, killing most of the photosynthetic plankton that formed the basis of the food web in the shallows. The Nautilus species that lived near the surface probably starved to death along with their relatives, the ammonites. Same but different: a chambered nautilus floats next to a cloudy nautilus, with its slimy outer layer. Photo by Peter Ward But in the perpetual twilight known as the Mesopelagic Zone, between 200 and 1,000 meters below the surface, other nautilus species persisted. And because today’s nautiluses are thought to be primarily scavengers, the mass death and destruction may even have benefited them, Ward suggests. After all, he says, “What was left after the end of the Cretaceous? Corpses.” A more personal tragedy kept Ward from field research on the Nautilus for several decades. On an expedition to New Caledonia in late 1984, his diving buddy drowned while the pair were checking nautilus traps. The 2015 expedition was his first foray back into Papua New Guinea. The group, which included Barord and TNC’s Richard Hamilton, traveled to Ndrova in a 14m two-masted canoe that Matawai had built for a climate change awareness trip a few years earlier. The island is a particularly good spot for nautilus research: the sea floor drops so steeply from its shores that a trap set hundreds of meters below the surface can simply be tied to a coconut. The head of Ndrova, Peter Kanawi, welcomed the researchers and 18 community members joined the mission as assistants. Each afternoon, as the tropical sun sank into the sea, the team set out in small motorized boats and lowered the traps — cubic metal frames covered with chicken wire and baited with tuna. At dawn, they pulled the ropes by hand—a grueling workout that took nearly an hour per trap—stopping when the cage was a breath away from the surface. Your browser does not support the video component. Researchers studying nautiluses in Papua New Guinea trap the animals in their shells to weigh, measure, take samples before returning them to the water. Video by Dave Abbott The first night, the traps caught nothing. Some locals assumed that the foreigners had not been properly introduced to the ancestors. But an older fisherman who was on the previous expedition recalled that the traps had been set in a different spot in 1984, at a slightly shallower depth. On their next outing, the group did as he suggested. In the morning, Hamilton dropped into the sea to check the trap. A coral reef biologist used to studying the shallows, he eagerly awaited this daily revelation. “You feel like a little kid taking a lucky dip. It was all that I hadn’t seen before—kind of a visual appreciation of how much you don’t know.” Sometimes there were strange eels, and Hamilton was particularly fond of “strange crabs.” But that day, he was thrilled to count three fuzzy nautilus and three chambered nautilus. Nautilus are accustomed to the deep and cannot survive long in the warm surface waters of tropical seas. So, once back at the compound, the scientists placed the animals in a cooler filled with seawater, chilled with ice water bottles. It was obvious who the fuzzy nautiluses were. Their shells were covered with a coarse, hairy periosteum, or outer layer, which is completely absent from other types of nautilus. “It feels like liquid slime…
