A quick question which I have been unable to find an answer to. Do fish fart?

–Alan, via the Internet

When you get a question like this you think, “This is a golden opportunity to brighten up scientists’ dull lives.” I sent urgent inquiries all over the globe. Best response on the subject of whether fish fart: “They do if they’re male.”

Fish flatulence has not been a major focus of biological research, so the following is somewhat tentative. To some extent the answer depends on how you define “fart.” Many fish have a swim bladder that they inflate or deflate as necessary to maintain buoyancy. Usually any expelled gas exits from the mouth and would properly be considered a burp. However, the sand tiger shark, Carcharias taurus, gulps air into its stomach at the surface, then discharges it out the back door to attain the desired depth. Surely this qualifies as flatulence in the common sense of the term.

But purists may object that this isn’t true farting–that is, a by-product of digestion. We then get into a somewhat speculative realm. In theory any animal’s metabolism produces carbon dioxide, while bacteria in the gut produce methane. Both must be purged lest the fish lose the ability to control its buoyancy. Carbon dioxide is typically eliminated via gas transport to the gills, but methane has to escape some other way. However, actual sightings of farting fish are rare–and let’s face it, underwater this isn’t a phenomenon that could be easily concealed. Some experts say digestive gases are consolidated somehow with the fish’s feces, which are packed into a gelatinous tube and then expelled. (Frequently the fish then eats this–not for nothing is the study of fish called ichthyology.) The point is, no farts.

Some fish observers claim they see a telltale bubble or two escape from the stern of a fish after it has gulped air at the surface (I have heard this said of tarpon). But again, this is not strictly a product of digestion. On the Web I have seen the claim that inasmuch as coral is made of calcium carbonate, which when combined with stomach acid produces carbon dioxide, coral-eating fish ought to produce farts in abundance. If true, it seems to me, the critters in the vicinity of a typical coral reef should emit forests of bubbles unequaled since the days of Lawrence Welk–not the impression one usually gets. Then again, few visit reefs specifically for the purpose of detecting fish farts. In short, Alan, much research remains to be done. Maybe you could organize an expedition and let us know.

In your discussion of angels dancing on the head of a pin in The Straight Dope Tells All, page 133, you write, “Martinus Scriblerus . . . is a pseudonym of a sort in common use among Enlightenment satirists.” This is a little misleading: it’s the name of a fictional author invented by Alexander Pope, John Arbuthnot, Jonathan Swift, John Gay, and Thomas Parnell, founders of the Scriblerus Club and coauthors of The Memoirs of Martinus Scriblerus. Haven’t got a copy of this handy to see if the passage indeed turns up in chapter seven, but we’ll leave that to you.

–Nate and Jane Dorward, Willowdale, Ontario

Told you my 18th-century files were a mess. I have, however, located the indicated volume, said to be the origin of the satirical claim that Scholastic philosopher Thomas Aquinas once debated how many angels could dance on the head of a pin. Turning to chapter seven, we see that Pope and his fellow smart alecks indeed poke fun at some of Aquinas’s more esoteric speculations. However, the question of how many angels can dance on the head of a pin is not among them. Thus, while we know that Aquinas did argue whether several angels can be at the same time in the same place (solemn conclusion: no), we still aren’t sure who gave the discussion its modern comical twist. Alan, when you get to the bottom of fish farts, see what you can do with this.

Art accompanying story in printed newspaper (not available in this archive): illustration/Slug Signorino.