Absurd Creature of the Week: The Curious Case of the Elusive, Slimy Nautilus
Aside from losing a $20,000 camera, by most measures July’s hunt for the ultra-rare crusty nautilus was a rousing success. The camera was stuck 1,000 feet deep when Rick Hamilton at last pulled up Allonautilus scrobiculatus in a cage off the coast of Manus Island in Papua New Guinea. And so he grabbed his GoPro and leaped into the water, capturing the first-ever video of a live crusty nautilus, a creature that human eyes haven’t glimpsed since 1984. It was a beauty, and it was…really slimy. And not to tell nautiluses their business, but they aren’t supposed to be really slimy.
You’re probably familiar with the nautilus. It’s that cephalopod (a group that includes the squids and cuttlefish and octopuses) with a beautiful tiger-striped shell that scoots around Earth’s oceans and occasionally runs into things. But this slimy, fuzzy nautilus, it’s more mysterious—far more mysterious. That’s changing thanks to the work of Hamilton, who directs the Nature Conservancy’s Melanesia Program, and other scientists. Not to mention that $20,000 camera, which put in a solid effort. May it rest in peace. (“We still know where it is,” says Hamilton. “I just can’t get it unstuck. I was thinking about selling it on eBay with a ‘pick up as is, where is’ clause.”)
Throughout history, humans have coveted the gorgeous shell of the nautilus—which tends to float around and wash ashore, as many as 11 years after its owner died—for all manner of uses. People turn them into things like jewelry or use them as chalices, which is pretty damn baller. The shell is impressive on the outside, but even more impressive internally. It’s divided into chambers, which progressively shrink as the structure spirals toward the center. By pumping water in and out of these chambers, the animal can control its buoyancy.
The incredible nautilus shell. The actual animal lives only in that big chamber, pumping water in and out of the smaller ones to control its buoyancy. It’s like having an arm floaty–that humans sometimes use as a cup.
So, the crusty nautilus’ hairy, yellow slime. It’s a sort of protein-dense skin called a periostracum, something you’ll also find on bivalves and oceanic snails. “It feels like wet moss,” says Hamilton. “If you push on the nautilus it’ll actually come off, it’ll flake off.” (The creature is informally known as the crusty nautilus because it’s encrusted with this layer of slime, not because it’s brittle or irritable or anything.)
The skin is an adaptation, Hamilton figures, to help the crusty nautilus avoid a trip to the stomach of a predator. This is, after all, a sluggish creature, relying on its armor to survive, as opposed to its cousin the cuttlefish, which instead deploys astounding camouflage. Of particular concern for the crusty is its other cousin the octopus. “They’ll attach onto the shell and drill a hole into them,” says Hamilton, “and then inject a poison that kills them, then pull the meat out. And we think that perhaps the crusty skin makes it a bit slippery. It’s a bit harder for the octopus to attach to the shell.”
You might ask yourself, then, why only the crusty nautilus would get all slimy while another nautilus it shares a habitat with, Nautilus pompilius, does not. And the answer may come down to lifestyle choices. Nautiluses are largely scavengers, feeding on things like fish that have perished and sunk to the ocean bottom, and typically they hang out in the dark depths, wandering great distances along the seafloor.
But the crusty nautilus is different. Hamilton and his colleagues pulled up a total of eight crusties, successfully tagging one of them as well as one pompilius. Then they tracked their movements. They found that while pompilius tends to migrate horizontally along the seafloor, the crusty nautilus is going about things more vertically. During the day the crusty hangs out in the relative safety of the darker depths, but at night it ventures up the water column, scavenging on reef faces as it ascends. Here it finds an abundance of food—after all, a reef is far more biodiverse than the deep seafloor.
Now, nautiluses, like Batman, rely on darkness for protection. But the crusty nautilus’ roving lifestyle likely exposes it to more predators in the moonlit shallows. Thus would it do well to have a slippery shell as an extra precaution. The creature’s migration may also explain why “compared to the other nautiluses, it’s a bit like the tank of the battlefield,” says Hamilton. “It’s a solider animal.” Being a little beefier would bestow it yet another advantage as predators lurk about.
Where the six species of nautilus can all agree, though, is how sweet it is that they live for so long—like, maybe as long as 100 years. That’s particularly weird because, in general, nature says the bigger you are, the longer you live. A blue whale will live far longer than a fruit fly, for instance. For its size, the nautilus shouldn’t be living anywhere near a century. And why that is isn’t yet clear. Even stranger, other cephalopods like squid and octopuses tend to be short-lived—maybe just a year or two.
That’s not all that separates the nautiluses from the rest of the cephalopod pack. Cephalopods showed up some 550 million years ago—way, way early in the history of complex animal life. Back then, the tentacled beings all had shells, but as the millennia wore on, they diversified and lost their armor, instead opting for camouflage and speed.
The nautilus, though, couldn’t be bothered with such change. It first showed up an incredible 500 million years ago and has held onto that shell all along. And considering the nautilus’ epic time on Earth, the crusty variety showed up really recently, perhaps as few as a million years ago. That’s nothing as far as evolutionary time is concerned. You’re looking at a species in its infancy, one science is just beginning to understand.
And it’s not just scientists who are interested in the nautilus-rich waters of Papua New Guinea. This may become one of the first places on Earth to open up to undersea mining. Way down at 3,000 to 4,000 feet deep, hydrothermal vents bring up valuable things like gold and silver. While that’s too deep for the nautilus, science still knows very little about how the deep works not only as its own habitat, but how it intertwines with the habitats above it.
And so further research in Papua New Guinea’s waters—with the nautilus or otherwise—is pivotal. “We can start to give communities and governments, etc., some sort of baseline understanding of what is down in that deep, deep water, which is potentially going to be mined,” says Hamilton. “There’s an incredible diversity down there.”
So here’s to exploration—preferably the scientific variety before the drilling. Oh, and the name of the outfit that’s fixing to mine Papua New Guinea’s ocean depths?
Browse the full Absurd Creature of the Week archive here. Know of an animal you want me to write about? Are you a scientist studying a bizarre creature? Email [email protected] or ping me on Twitter at @mrMattSimon.
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