Fuzzy Nautilus Rediscovered and Filmed
“Nautilus.” The name conjures images of Jules Verne and the United States Navy with its first atomic submarine, and hidden between them, the name-giving animal itself.
Among biologists it is this animal that inspires most, for the simple reason that it appears to be one of the great survivors on Planet Earth: a living fossil.
Coming from stock that first appeared near the end of the 530-million-year-old Cambrian Explosion, when animal life first appeared in our planet’s global ocean, the nautiloid cephalopods have endured through both good times and bad, including times very, very bad indeed: the great mass extinctions, short intervals of time when most species on Earth died out. Thus survivors such as the nautilus are revered by science.
Unfortunately, it is the very popularity of their beautiful, iconic, spiraled, and internally chambered shells that threatens them most, more than meteors from space, atmosphere-polluting global volcanoes, or even long-enduring ice ages ever did. Surviving mass extinction events is one thing. Surviving the global spread and increasing numbers of humans and our desire for shells and cheap trinkets made from those shells is something else entirely.
Now nautiluses must face another challenge: humans’ desire for metals found most abundantly on the sea beds these ancient survivors call home. And despite all these threats, and the nautiloids’ long history, fascinating discoveries are still being made about them.
The Other Nautilus
At most sites around the Earth, nautiluses can be found at depths between 300 and a thousand feet. They live singly (never in schools), they grow slowly (taking up to 15 years to reach full size and reproductive age), and they are never overly abundant as they slowly swim over the deep sea beds searching for carrion on the bottom.
In all but one place on Earth, only a single nautilus species can be found at any one site.
Northeast of the main island of Papua New Guinea however, along the coast of Manus Island, made famous by the American anthropologist Margaret Mead in the earlier part of the twentieth century, not only can you find the well-known chambered nautilus (genus: Nautilus, species: pompilius) but south of Manus there is a second species as well. It was first seen alive in 1984, and was found to be so astoundingly different in shell and soft part anatomy that it was, in 1997, give a wholly new genus name: Allonautilus (and species name scrobiculatus). And then, for the next 30 years, it wasn’t seen again.
Recently, National Geographic and the US National Science Foundation (Polar Programs) sponsored an expedition back to the site where Allonautilus was last seen, and the team succeeded in finding it anew.
The Mission: Snap Pictures, Snip Samples, Leave ‘Em Alive
The goals of this trip were to most broadly ascertain if they still existed at all. I was the organizer of the trip, but could not have gone forward without Greg Barord, whose recent PhD on nautilus biology is changing our understanding of this animal; Rick Hamilton of The Nature Conservancy, who spends much of his life doing conservation science in Melanesia; and Manuai Matuwae, local chief of conservation for the Manus Island area, and the real mover and shaker of our field work.
My prior field work in the Philippine Islands, done with Greg on four trips from 2011 to early 2014, has already shown that local populations of Nautilus in the Philippines have been fished to extinction, and the fear was that perhaps the same happened to Allonautilus in PNG in the thirty years since it was last seen alive. But beyond that, if found, the goal was to get the first digital photos, the first live videos, and most importantly, get small snips of flesh, taken in non-lethal fashion, so that the new and powerful DNA techniques of modern genetic science could better understand these animals.
A further goal was, almost ironically, to use bits of shell taken from living nautiloids in a very warm tropical setting, to better understand ancient nautiloids that lived right before and after the great Cretaceous-Paleogene mass extinction in Antarctica, a very cold setting indeed for us field workers when down there now.
Living Fossils and Fossil-Fossils
On four extended field trips sponsored by Polar Programs, I pondered the problem of why the fossil nautiloids so common at our Antarctic field sites survived the catastrophic mass extinction of 65 million years ago ending the Cretaceous, while their near look-alikes, the ammonites (also cephalopods with chambered shells) utterly died out. One group lives, one dies. As the great, and sadly recently deceased paleontologist David Raup famously asked, “Was it good genes? Or simply good luck?”
The question was partially tractable by our Antarctic field work, and it was the generosity of National Geographic and the Waitt Foundation as well as NSF Polar Programs that allowed this current trip to be possible, the leadership scientists there understanding that the present is indeed the key to the past; that we also needed to study the living descendants as well as the Cretaceous dead, which took us to this study of extant Nautilus and its cousin, Allonautilus, at the sole known place where both can be found.
Sending Their Secrets Up From the Deep
Additionally, two other techniques not available in 1985 were brought to the field site: deep water video cameras and small acoustic transmitters that could be attached to the shell. If monitored overhead day and night from small boats fitted with appropriate electronic receivers, these transmitters would obtain priceless information on the habits, depths, and even temperatures at which Nautilus and Allonautilus live on the same shared, deep reef environments.
Which led to our day-to-day life. We worked around the clock, with Rick, Manuai, and Greg taking turns with me as we sat in small boats day and night to retrieve the signals of our tagged nautiluses, living their lives far below but informing us of their depths, position, and temperatures of habitation for six days and five nights straight. The heat was a force—oppressive, the afternoons barely breathable; and it is in such times that companions can make the hardship bearable—others living the same hardships and not complaining.
The great joys were the moments we retrieved our traps to find nautiluses, the times we would swim with them, and especially when we pulled our giant, heavy deep-water video systems from the sea and spread out on the lawn on our small island. We’d bring our entire, 40-person clan together and watch the premiere of each 12-hour movie of the night before (played back faster than normal) to watch the nautiluses, deep-water sharks and other fish, and invertebrates of every stripe march into the camera’s field of view in search of the rich fish bait attached to its bright light.
Happily (and in spite of the rigors of working from small boats in equatorial heat and humidity, the latter playing havoc with all electronics, computers, and cameras), all goals were met. None of the nautiluses we saw or briefly collected were “sacrificed for science” (i.e., killed and put in alcohol for eventual existence on a museum shelf).
The data and photos tell us that both of these nautiloid cephalopods exist still. The possible bad news is that their habitat—this part of Papua New Guinea where uniquely in the world two genera of nautiloid cephalopods live—is slated soon for large-scale, deep-water mining that will dredge the sea floor, a seafloor above which these ancient survivors still live.
But for how much longer?
Source:
Fuzzy Nautilus Rediscovered and Filmed After 30 Years | National Geographic (blogs)
