When we saw the memes scoring the size of a blue whale’s anus second to some of the year’s most reviled politicians, our first thought was that it was deliciously funny. Naturally, our next thought was, “Is this true?” and “How big is a blue whale’s anus, anyway?”

The first obstacle getting an answer to these pressing questions was persuading scientists to answer interview requests. One admitted that at first, he assumed his colleagues were messing with him. Once convinced our request was not a joke, the situation improved only slightly.

“Most of the data that we have on large whale species comes from back in the day when we used to kill a lot of them,” says Dr. Matt Leslie, a visiting assistant professor of biology at Swarthmore College. And by “a lot” Leslie refers to a whaling industry that killed 2 million to 3 million blue whales, likely restructured marine ecosystems, and nearly drove them extinct. “And to be honest,” Leslie says, “there wasn’t a whole lot of interest in an anuses.”

Marine mammal illustrator and American Cetacean Society President Uko Gorter agrees, “The rectum or anus of whales escaped scientific scrutiny for centuries. There was—and still is— simply no interest in documenting its absolute size, or its capacity for super flatulence.” Whalers were much more concerned with how much blood, meat, and blubber the whale could provide. Though whalers sometimes did note an especially impressive penis.

“If you were to just take a blue whale and roll it over—as if that were easy to do—the female is going to have a slit, like right at the base of her tail,” Leslie says. That slit covers both her genitalia and anus, and while whalers “didn’t spend a lot of time fishing around inside of the slits,” he says, they did take measurements from the anus to the clitoris, or the length of the slit, which for the largest whales measured four to five feet. (Males have two slits: one each for the anal opening and the penis.) Today few of these giants are left, so we can view this measure as a whale butthole upper bound.

Now an anus is the end of a poop chute, and from an engineering perspective, the size of the anus is directed by the size of its contents. Fortunately, poop research is non-invasive and legal. Dr. Nick Pyenson, curator of fossil marine mammals at the Smithsonian and author of Spying on Whales, and Stanford University biology postdoctoral fellow Dr. Matthew Savoca, have studied whale defecation and hope to publish their research soon “The whale poop I have been around typically is a five or six on the Bristol Stool Scale so it’s not as though they’re passing blocks the size of a refrigerator or something,” Savoca says.

The Bristol Stool Scale, in case you are not familiar, was developed in 1997 by the Bristol Royal Infirmary as a tool to help patients and their clinicians better communicate fecal appearance and consistency. It ranges from Type 1—hard, nut-like poos—to Type 7, which is pure liquid. Type 5-6 then lands somewhere between “soft blobs with clear-cut edges,” and fluffy, raggedy edged bits. The Stool Scale is a quasi-quantitative rating system that in this case offers us a more visceral understanding of the quality of poo a whale’s anus is responsible for.

In Pyenson and Savoca’s pictures, yellow-gold, salmony-pink, and coppery brown feces plume behind the whales for several feet “Their poop is not like ours” Pyenson says. “It’s not like floating logs in the ocean. It’s much more diffuse, kind of like fuzzy, almost fleecy.” “To put it bluntly,” Gorter says, “no turds.”

The meme likely assumes that animal anus scales with animal size says Dr. Dara Orbach, an assistant professor of Marine Biology at Texas A&M University-Corpus Christi, but that is not always true. She notes that blue whales also have relatively small brains for their body size. Blue whale anuses likely aren’t huge because what they eat is tiny. Blue whales are baleen whales, and feed by straining tiny shrimp-like animals called krill from massive amounts of ocean water. Unlike wombats or horses or humans, their poops are not full of woody fiber and so resemble liquidy jello.

Sadly, just how much a blue whale’s anuses could stretch remains a mystery. “It would be very straightforward to test the stretching capacity of an anus using biomechanical approaches (tensile test) but getting a fresh blue whale anus would not be easy. In my sampling of over 400 marine mammal reproductive tracts, I have never received a blue whale specimen and the blue whale that I necropsied had its genitalia eaten by sharks.” Hopefully after death.

So just how big is a blue whale’s anus? Leslie and Pyenson, independently arrive near the same estimate: around 10-15 centimeters, like a large grapefruit. But one source suggests they could be bigger. In Ostéographie de la baleine échouée à l’est du port d’Ostende le 4 novembre 1827, a book published in 1828 by J. Dubar, plate 13 shows a detailed drawing of a 25 meter long female blue whale’s vulva and anus.

The scale bar, which according to Gorter likely measures in 10cm increments, indicates that an anal opening around 15-20cm. But by the time the drawing was made, the whale had already started to decompose, making for a larger than normal orifice. “Another image supplied by Gorter from “Southern Blue and Fin Whales” by N.A. Mackintosh, shows the underside of a dead whale with a man in the frame for scale. It’s tough to tell, but here the anus looks about the size of a grapefruit.

So dear readers, what have we learned? First, you cannot trust a meme because unlike us the creators do not always exercise due diligence. Second, when you think of blue whale anuses, think grapefruit. And finally, that politician very well may be the world’s biggest a**hole after all.

https://arstechnica.com/?p=1732246