John Gamel asked:
Here's a good question of the week: Do fishes fart?
For some strange reason this thought came to mind while I was in my bath. As a physician I know that human flatulence comes from two sources: swallowed air or gasses produced during digestion. Since fish can't swallow air, perhaps their digestion also produces gases. Love to hear the facts from an Ichthyologist.
We put this to Eleanor Drinkwater, from the University of Cambridge...
Eleanor - I think this is a fantastic question. I absolutely love this question, and I can say categorically that some fish do fart. In fact, a recent study discovered for the first time that herring fish produce farts (fart noises), which they think they use for communication.
Kat - Herrings talk to each other by farting!
Eleanor - Apparently. They discovered that if they put more and more fish into a tank together, the increase in fart noises would increase disproportionately to the number of fish.
Chris - When you say fart noises. So you literally mean as in farting noises?
Eleanor - Well, yes. Itís a small jet of air which comes out of the anus.
Chris - Where do they get the air from because, as is pointed out in the question, fish donít breath air and when we swallow air, some of it emerges at the back end and the bugs in our gut metabolise some of it to gas so, where do the fish get theirs?
Eleanor - Different fish are kind of put together differently. In the case of herring fish, they have their swim bladder, which is a little sack of air that helps them with buoyancy around the place under the sea, is attached to their gut. And they can actually gulp air in from the surface and they do produce a little bit of gases themselves, which then go from there into the swim bladder. If the swim bladder gets too full, they want to change depth, they can then spit some of the water back out. So yes, thatís where the herring get their farts from.