Allonautilus scrobiculatus is a species of nautilus that hasn’t made an appearance for over three decades. Take a look at how it compares to a more common species of nautilus, and learn how nautiluses are more isolated than you might think.

Peter Ward, a biologist from the of the University of Washington, was baiting nautiluses out near Papua New Guinea this August. The procedure, putting a piece of chicken on a stick, sending that stick down to about 500 to 1,300 feet below the surface of the ocean, and filming the results. The nautilus is a good scavenger, so he was expecting to see a few, but he probably wasn’t expecting to see Allonautilus scrobiculatus. The last time he’d seen the thing was in 1984, when he and his colleagues were astounded to see a nautilus with a kind of furry slime coat climb into view.

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This particular nautilus isn’t just externally different. It has tweaks to its mouth and genitalia, which make it legitimately its own species. Nautilus are very old, but they differentiate because they often live in kind of reverse islands on the ocean floor. The nautilus can’t go too low, because the pressure will get to it. It also can’t go too high, because eventually the water gets too warm, so whole populations are isolated in pockets. This means that Allonautilus scrobiculatus might be in trouble. If fishing and mining destroy its pocket, it goes extinct.

Which would be a shame, because any nautilus is an undeniably cool animal. It’s been floating around the oceans, mostly unchanged, for 500 million years. Plus, its chambered shell inspired one of the great poems, by Oliver Wendell Holmes Sr, father to the Supreme Court Justice.

Build thee more stately mansions, O my soul,

As the swift seasons roll!

Leave thy low-vaulted past!

Let each new temple, nobler than the last,

Shut thee from heaven with a dome more vast,

Till thou at length art free,

Leaving thine outgrown shell by life’s unresting sea!

Well, I like it.

[Source: University of Washington]

Images: Peter Ward

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