O(pabinia) Week

Transport yourself back 505 million years ago to the middle Cambrian. The earth is unrecognizable. The continents we know today have not yet formed, and the greenery we associate with life has not yet evolved. The land is barren and rocky. The oceans, however, are brimming with life, and it is some of the most diverse you’ve ever seen. There are countless strange arthropods, some spikey, appendaged, or covered in armor, but among them, one is sure to stand out: Opabinia regalis — the ceaselessly mocked and pondered five-eyed wonder of the Cambrian.

Seemingly drawn to life from the sketchbook of an imaginative 6th grader, Opabinia is of an undeniably unusual form. It has five protruding compound eyes, a body lined with flower-petal-like appendages, and a clawed proboscis. Opabinia used its flowery appendages to swim slowly across the sea floor in a flapping movement, and steered using its upright angled tailfins. While hunting for prey it used its proboscis to seize its food and then scooped it into its mouth. Still, Opabinia lacked any form of jaws (Whittington, 1975), so although it may have been able to fetch underwater pringles, it could not have had any itself. Instead, it is likely Opabinia fed on soft prey like worms.

“Seemingly drawn to life from the sketchbook of an imaginative 6th grader.” Image courtesy of ResearchGate.

Because of its unique beauty, Opabinia defied the limiting taxonomic classifications of the time. First discovered in 1911 by Charles Doolittle Walcott in the burgess shale (a prolific fossil site known for its detail of Cambrian life), Opabinia was thought of as a crustacean. Later, it went under consideration for the rank of arthropod but was turned down due to its lack of jointed legs. It was also tried as a worm, and very shortly as a trilobite, but nothing was sticking. This is cruelly reinforced by the website for the University of California Berkeley Museum of Paleontology. The site displays a little low-res Opabinia you are supposed to click so it can be added to the tree of life, but when you do so, it drifts erratically, until it settles into a separate branch accompanied by a question mark and fades to gray. Eventually, Opabinia found its way back into the arthropod crowd, but only as part of a stem group, entering the family of Opabiniidae where it once stood alone. Not that it needs any other organisms, because even though it composed only 0.006% of the fossils in its community (Royal Ontario Museum, n.d.), Opabinia is more than enough.

Sometimes, however, this world isn’t ready for a fellow with a clawed proboscis. When Opabinia was first shown at an Oxford paleontological meeting it was greeted with laughter. But Opabinia did nothing to deserve this mockery, if anything we are better for Opabinia’s perceived oddity as it allows us to see a form of life most of us could not imagine if we tried. And yes, it did swim “feebly” (Whittington, 1975), but maybe it’s okay to swim a little slower and take life a little easier — we’ll all end up in our own Burgess shale one day, why not appreciate the sea floor while we can. And maybe Opabinia didn’t just need its five mushroom-like eyes to look out for predators, but also haters, and shouldn’t we be doing the same?

Despite all odds, Opabinia is no longer alone. A new family member of the Opabiniidae was classified in 2022: Utaurora comosa. Despite a few minor differences, including four more pairs of tail blades, Utaurora is an obvious match. The recent inclusion of additional Opabiniidae challenges long-standing views that Opabinia was a lonely weirdo, instead, Opabinia is now a weirdo with a pal. Once again illustrating the age-old lesson that no matter how many paleontologists laugh at us, we can still find like-minded company. 

It is an endless tragedy that Opabinia is still shrouded in relative obscurity because the mind boggles at all this creature could teach us. After all, aren’t we all tiny, bottom-dwelling, uncategorizable, creatures swimming through the sea of knowledge plucking with our limited- range proboscis, just trying to grab onto something real? And sure, maybe we are limited to the soft foods of what our mortal minds can comprehend. But that didn’t stop Opabinia. It kept (until its extinction) flapping, its lateral lobes and catching those worms, and so should we.

Because I am as of yet unaware of one, to conclude this ode to Opabinia, I have written a brief eulogy for our finned friend: 

Rest easy, Opabinia. Taken too soon. 

You were one of my favorite Permian critters (and my favorite with a proboscis).

You would have loved Jamba juice and the Tully monster. 

With your utter disregard for evolutionary norms, you inspire me, and countless paleontologists.

Though you were less than 3 inches long, your influence is immeasurable. 

Cheers to you, Opabinia.

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