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Last year, the staff of Science Friday came across a tweet that caught our attention, sent out by researcher Dr. Maureen Berg. It read: “Hello, does anyone know of any animal that has a few butts? Like, more than one, but fewer than 100? I’m generally talking butts as the anus, but I’m open to other interpretations.”

hello does anyone know of any animal that has a few butts*? Like, more than 1, but fewer than 100?

*generally talking butts as the anus, but I’m open to other interpretations

— Dr Maureen Berg (@MaureenBug) January 20, 2022

Turns out, it was a call to source comic ideas for Invertebrate Butt Week, a celebration of—you guessed it—the butts of invertebrates. “Invertebrates really get the short end of the stick,” says Rosemary Mosco, the creator of the comic series Bird And Moon and #InverteButtWeek organizer. “People are not as excited about them as, say, a majestic whale or a beautiful bird. And I love my birds, but [invertebrates have] such an incredible diversity. So, butts are sort of a cheeky way to access some of that amazing diversity and celebrate it.”

Rosemary and other illustrators and scientists teamed up to create #InverteButtWeek, a celebration of the behinds of the backbone-less. “It’s a chance for some people who do science communication to do the silliest thing that they can possibly think of,” says Dr. Ainsley Seago, curator of invertebrate zoology at the Carnegie Museum of Natural History.

Ah, the beautiful butts of the sea.
A few weeks ago, some twitter folks saw the news about a new marine worm that had 100 or more butts. We decided to collaborate on this comic. My co-conspirators here are @MaureenBug and @americanbeetles. #invertebuttweek pic.twitter.com/SAZI3fqaFM

— Rosemary Mosco (Bird And Moon Comics) (@RosemaryMosco) March 1, 2022

With the powers of @spissatella & @RosieRiots‘s science by my side, we present:

The Butt Political Spectrum ™

What is A Butt? How do you even define a butt?
Tag yourself I’m Butt Chaotic#InverteButtWeek pic.twitter.com/inLEU9ODWV

— franz (@franzanth) March 1, 2022

Universe of Art’s D Peterschmidt talks to the organizers of #InverteButtWeek about how it came together, their favorite invertebrate butt facts (like how sea cucumbers have anal teeth), and how you can see the illustrations people created.

Universe of Art is hosted and produced by D Peterschmidt, who also wrote the theme music. Charles Bergquist and John Dankosky provided production assistance. Our show art was illustrated by Abelle Hayford. Support for Science Friday’s science and arts coverage comes from the Alfred P. Sloan Foundation.