For the bolson pupfish, a good fart can be a lifesaver: These little fish live in shallow pools in Mexico where they slurp algae off of rocks and burrow into the sediment to hide from predators. When temperatures rise in the summer, the algae squirt out gas bubbles that the pupfish suck down when they eat — making them bloated, and, worse, buoyant.

The puffed-up pupfish float back to the water’s surface where they’re easy pickings for predators. But that’s not even the worst part: if they don’t fart in time, “sometimes, it’s so bad that they explode,” says Dani Rabaiotti, a zoology graduate student at University College London.

These pupfish are among the 80 different animals that Rabaiotti, her co-author Nicholas Caruso, a postdoctoral scientist at Virginia Tech, and illustrator Ethan Kocak describe in the new book Does it Fart? The Definitive Field Guide to Animal Flatulence. Released in the UK in October 2017 by the publisher Quercus, the US edition, published by Hachette Books, will be available on April 3rd, 2018.

The book basically started when Rabaiotti’s 19-year-old brother asked her if snakes farted. She didn’t know and passed the gas question to Twitter’s favorite snake expert, David Steen. (He replied that, yes, snakes do indeed fart.) That’s when Caruso suggested the #DoesItFart hashtag that proceeded to go viral in January 2017. Rabaiotti thinks that Caruso was just hoping people would “tweet loads of farts at David,” she says. “But it turned into something beautiful instead.”

The hashtag turned into a collective Google Spreadsheet, where scientists and Twitter’s fart experts could add flatulent factoids — with the appropriate scientific citations. “And then at that point our publisher, Quercus, got in touch and said, ‘Do you guys want to turn this spreadsheet into a book?’” Rabaiotti says. “So obviously, we said yes.” Rabaiotti and Caruso became co-authors, and suggested Kocak as an illustrator. Kocak, a herpetology enthusiast and illustrator of the Black Mudpuppy webcomic (named after a type of salamander), has drawn hundreds of scientists’ avatars on Twitter — including Rabaiotti’s and Caruso’s.

The three teammates have actually never met each other in person, since Rabaiotti is based in the UK, and Caruso and Kocak are in the US. Instead, the three collaborated using a combination of Skype, email, Twitter, and Google Docs. “Needless to say that our emails and search histories are forever changed by this last year,” Caruso says.

The Verge spoke with Rabaiotti, Caruso, and Kocak on a conference call about fart-catching devices and gonad-eating parasites.

This interview has been edited for clarity and brevity.

What does a creature need in order to fart?

Ethan Kocak: Mostly a butthole.

Dani Rabaiotti: They need a hole at the opposite end to their mouths. That’s probably the main thing. It doesn’t have to be a butt, necessarily. There are all different sorts of ducts, cloacas — as long as it has some sort of hole at the opposite end to its head, where gas can come out.

Let’s back up: How exactly did you define a fart?

Rabaiotti: Most air that we fart out is swallowed — so it doesn’t [just] come from digestion. And a lot of the animals we’re encountering do things like suck air into their butt and shoot it back out again. So, it wouldn’t fit the medical definition, but it definitely is in keeping with what people would think of as a fart.

Some turtles can breathe through their butts, right? How would you categorize that — is that a fart?

Nicholas Caruso: They obviously do fart other than the butt-breathing. So the answer would be “yes” — to begin with. But then it’s like, “Oh, but also they breathe through their butts.”

Rabaiotti: I’m glad I’m not a turtle.

What was the most surprising thing that you discovered while researching, writing, and illustrating this?

Rabaiotti: How much was unknown. We spend so much time researching animals, but for a lot of species we just have no idea whether they fart or not. And that was surprising, because it seems like quite a big knowledge gap. If we don’t know if an animal farts, then we probably don’t know a whole lot about how they digest their food.

Caruso: I would definitely agree. Along with that, it was surprising that this silly Twitter joke has turned into so much more. People seem to be genuinely interested in farts.

Kocak: It has instant appeal, because everybody farts.

Rabaiotti: Not birds!

Kocak: Well, I don’t know how many birds are buying the book...

In the studies you read, how were scientists testing whether these animals farted?

Caruso: Specifically with domestic dogs, [scientists] actually developed this coat that had a test tube attached to the end. So they were able to put this coat on a dog, the test tube went where you think it would go, and this allowed the dog to be able to walk around and eat and do its thing so they could do non-invasive gas extraction, as it were. And so they actually used this to do gas analyses and with a dedicated smell tester — which sounds horrible — to rank how bad it smelled. It seemed like a noble effort.

Rabaiotti: In quite a lot of papers, they just put animals into a chamber where they could measure the gas when they took the animal out. But the problem with those studies was that you didn’t know what end the gas was coming from. So I found this paper about sloths where it was like oh, they produce loads of methane! And I was like yeah, but are they farting it out, or are they breathing it out? And then I had to go on this really long investigative journey to try and find out if sloths fart. I even started planning putting one in front of this methane camera so you could see which end the methane was coming out. But in the end I got contacted by some experts who said that they don’t fart. Apparently if they get trapped wind, they’re probably dying. So, that doesn’t sound good.

Did this research process change your relationship to your own farts in any way, or the farts of those you love?

Rabaiotti: I think now everyone just gets really over-excited when you fart. Because I wrote a book about farts, farts are a big deal now.

For the illustrations, what were some of the challenges of visualizing the wonderful world of farts?

Kocak: The biggest challenge is that farts are normally invisible. But there’s a long rich history for cartooning, visualizing farts. So I drew on that a little. So sometimes they look like clouds. With the bird [which doesn’t fart], we did the dotted line and “Error 404.”

What are your favorite pages in the book?

Rabaiotti: Mine is the sea cucumber, even though it doesn’t fart. Ethan [Kocak] killed the illustration on that one, it’s so good.

What’s the face coming out of its butt?

Rabaiotti: That’s the pearlfish. Pearlfish go inside the sea cucumbers’ butt and eat their gonads. Just a good butt-fact to put in there.

Kocak: My favorite page is the sauropod killing the velociraptor with farts in the “Does it fart? Not anymore” dinosaur entry.

Caruso: Maybe the pupfish that’s just upside down and bloated. Just imagining a bunch of pupfish not farting and popping back up to the surface and being easy prey.

Kocak: Ah, the majesty of nature.

What is something that didn’t make it into the book that you’re very sad isn’t included?

Rabaiotti: The book is quite skewed towards mammals, especially primates — that was just because of who contributed to the spreadsheet and what they studied. I think there are a lot of interesting insects out there that didn’t get covered just because there weren’t as many entomologists that contributed in the first place. It just shows that we’ve got a bit of a bias towards the cute fluffy animals, and there’s loads of really interesting things in the invertebrate world as well.

Is that going to be book two, the insect edition?

Rabaiotti: We’ll see.

Caruso: We’ve had a lot of requests for a second volume, because of course people have tweeted at us ever since the book came out, “Oh hey, have you seen this? Have you heard of this animal?” We had no idea about even more research out there that we could have looked into.

Kocak: If we do a sequel, can we do something like, “2 Fart 2 Furious”?

Rabaiotti: Oh my goodness.