Can snails fart? Thank you. – Avalon, age 9, Scotts Head, NSW.
(Asked as part of the Curious Kids series where children ask questions, and experts answer.)
Lots of animals fart because of what they eat, but it was not easy for me to find a clear answer on whether snails really do. More research is needed to know exactly how the digestive system of a snail really works.
You might have heard about methane. It is a gas found in a lot of animal farts. I did find one study that said that scientists kept some snails in a glass container for one day and one night and checked if they would produce methane. And the snails did not.
(For the adults in the audience, the paper noted that, "In this aspect, the structure of the microbiota and in consequence the functioning of the digestive microbial ecosystem of the snails differs markedly from those of vertebrates, especially herbivores.")
You may have seen reports that scientists built a database showing which animals do and don't fart. Not every animal in the world is on there, but it does say that mussels and clams (which, like snails, are part of a group of animals called molluscs) do not fart.
Moon snails, which live in the sea, were also listed as a no.
One thing I can tell you is that a snail's bottom is right over its head. This is because snails are very different from other molluscs (which includes things like octopus and squid as well).
Because they are squashed into a protective shell, their body is twisted round to fit in. As a result, their bottom is just above and to the side of where their head comes out.
Gassy molluscs
Water snails, mussels and other molluscs do produce a gas called nitrous oxide if they live in polluted water.
You might have heard of nitrous oxide. It's also called "laughing gas". But this can be a problem, as nitrous oxide is a greenhouse gas and lots of it will add to climate change.
These mussels, when they are not producing laughing gas, produce something called "pseudo-faeces" which literally means "false poo". Because the food they eat (little plants and animals floating in the water which they suck in) can contain a lot of sand, they sometimes have to squirt it all out.
This doesn't come out of their bottom, but out of something called a siphon, through which they suck their food.
Bill Bateman, Associate professor, Curtin University.
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