Who among us hasn’t wondered if a snake can fart?
Dani Rabiotti, a quantitative ecologist, posed this question on Twitter in 2017. Her study of animal flatulence naturally went viral. From there, #doesitfart spread quickly (much like a, well, you know). Rabiotti and her co-author Nick Caruso turned the topic into a book that won the 2018 New York Times Bestseller list.
Put simply, a fart is “any gas emitted from the end of an animal opposite its mouth,” Rabaiotti and Caruso explain in their groundbreaking book Is it farting?: The ultimate field guide to flatulence in animals.
An animal may emit a fart from its anus (if it has one) or its cloaca (a combined opening for urination and defecation). The gas released causes the opening to vibrate against the organism’s sphincters, producing a sound.
Which animals can fart?
A great many animals can and do fart. Humans, of course, but so do hyenas, manatees, dogs, and bobcats. A whole host of creatures you might not expect also join in the chorus. As mentioned above, there are enough flatulent animals to fill an entire book.
Take the herring, for example. Not only can the fish fart, it does so intentionally to communicate. Herring fart at a frequency too high for predatory fish to hear, so their flatulence acts as a secret fish code.
Farts are not all the same and can serve different purposes. Passing gases can relieve intestinal discomfort or be used to communicate, as with the herring above. Farts can also be used to scare potential predators. When threatened, a Sonoran coral snake will suck air into its cloaca (the only opening snakes use for peeing and pooping) and expel it with a popping sound. Rabiotti and Caruso write that this “cloacal popping” sounds like a “higher, shorter version of a human fart.” Keep this in mind the next time you’re hiking in and around southern Arizona.
The Bolson killifish, found only in Mexico’s Cuatro Cienegas nature reserve, has the glorious distinction of being an animal that must fart to survive. The fish feeds on algae that produce gas. When the gas builds up inside the fish, it begins to float to the surface where hungry predators await. Farting causes the fish to sink back into the sediment where it normally resides.
Not only can American cockroaches survive absolutely anywhere, they can also fart.
Which animals can’t fart?
Some animals may fart but don’t do it, while others really aren’t able to.
Although bats should be able to fart, they don’t seem to be able to. This may be because they digest their food so quickly, preventing internal gas buildup. Most animals that digest their food can theoretically fart, although they may not do so audibly or frequently.
Animals that truly cannot fart do not have a digestive system that breaks down food into gas in an enclosed space (like an intestine) and then excretes it. A Portuguese man o’ war, for example, cannot fart. Technically, the man o’ war is a colony of specialized organisms and liquefies the prey it catches with its tentacles.
Birds generally don’t fart, Rabiotti and Caruso explain, because the food they eat moves through their digestive tract very quickly (no time for gas to build up) and their gut microbes are different (and produce less gas) than those of mammals. Whether amphibians fart is not yet conclusively known. Frogs’ sphincters are not very strong, making it less likely that the release of gases will cause vibrations strong enough to be audible.
Sloths are an exception among mammals and do not fart. They digest their simple food incredibly slowly and although their gut microbiome produces methane, this gas is absorbed and exhaled rather than released as flatulence.
This story is part of Popular Science’s “Ask Us Anything” series, where we answer your weirdest and most burning questions, from the mundane to the outlandish. Have you always wanted to know something? Ask us.
