In the Dune films a well as the book (IIRC), there is a situation where a worm swallows a spice harvester. E.g. in the film of Villeneuve:

To the extend of my knowledge, worms mainly feed on sand plankton and smaller worms, i,e. organic. How can they digest something made out of metal? I assume they digest it, as seen in the video, the Harvester is quite big and I assume a worm cannot simply "poop it out" whole again?

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    ripleys.com/weird-news/mangetout - Humans can eat things that aren't food. Presumably sandworms can do the same.
    – Valorum
    Dec 19, 2022 at 12:25
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    Sandworms probably have to be able to handle swallowing the odd boulder, so a crawler just fits into that mechanism
    – Nolimon
    Dec 19, 2022 at 15:02

2 Answers 2


Edit: @Luuan and others pointed out in the comments that rather the entire lifecycle of the sandworm instead of the sandworm itself is autotrophic and that sandworms also eat smaller worms and sand plankton.

"Now they had the circular relationship; little maker to pre-spice mass; little maker to shai-hulud; shai-hulud to scatter the spice upon which fed microscopic creatures called sand plankton; the sand plankton, food for shai-hulud, growing, burrowing, becoming little makers."

That doesn't mean, of course, that they don't also "eat" the sand to get minerals and such. My paragraphs are based on information that was available in the Wiki at the time of my writing. I will leave them in because the answer was already upvoted and accepted. Take these paragraphs with a grain of salt and assume that the truth is somewhere in the middle.

Paragraphs from my original answer:

Sandworms are described as autotrophic animals. That means they produce their own food. Plants are autotrophic, for example. They use photosynthesis as an energy source to convert water and carbon dioxide. The sandworms might employ some sort of chemosynthesis, using chemical reactions. Or they might use a process not actually found in animals on earth and connected to their unique physical attributes.

What the worms feed on is actually the very sand of Arrakis. Organic compounds in the sand are just something they swallow along the way, but not their main food source. They convert minerals and chemicals. Among other things they produce oxygen in the process. They are described in the books as massive oxygen factories.

It should be noted that sandworms don't swallows things from the surface because they consider it food. That is just the result of an extreme territorial defense instinct.

Edit: Most likely both is true, that some things they eat as food and other just to defend their territory.

I think the exact process of how a sandworm processes the sand and whatever else it swallows is never clearly explained. But Frank Herbert has his characters explain that "a sandworm's internal workings resemble that of a massive blast furnace, producing intense heat and flames"(see last paragraph here). The first mention of this was in "Children of Dune" I believe, but I'm rather sure that Leto II also mentions it in "God Emperor of Dune". Leto II explains that this is part of an adaptation to deal with the friction heat the worms generate when they travel through sand.

If the temperatures inside the worm are indeed that high, it stands to reason that it would simply melt down the swallowed harvester.

  • If they are indeed the primary source of oxygen for Arrakis, this presents a plausible mechanism for digestion of objects made from iron alloys (like a harvester, presumably). An environment of nearly pure oxygen and high temperatures would cause iron to oxidize into rust at a much faster rate than under normal temperatures and atmospheric oxygen levels. I can't give you plausible mechanism for how that oxygen forms, but an iron machine might disintegrate into rust relatively quickly in a hot, oxygen rich environment like that.
    – MikeyC
    Dec 19, 2022 at 21:42
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    The sandworm lifecycle as a whole is autotrophic; the actual sandworms aren't - they feed on both the sandplankton (the first stage of the cycle) and smaller mature sandworms (the third stage). While it's true that sandworms are very territorial, they do indeed swallow harvesters in a mistaken attempt to get food - the rhythmic sounds harvester factories (and humans) make are similar to what smaller sandworms sound like. "Interior furnace" is mentioned, but first by Leto II - and explicitly as part of an adaptation that deals with the friction heat the moving sandworm produces.
    – Luaan
    Dec 19, 2022 at 22:09
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    @Luaan If you happen to have some better online sources I'm more than happy to amend my answer. Especially about them eating the sand plankton and smaller worms. I seem to recall that only a few worms actually reach the giant worm stage and many probably get eaten along the way. But it is actually described as a main source of food? As to sandworms swallowing objects from the surface, I guess it might be both. Smaller things like people might seem like food to them. But something as big as a harvester might cause enough vibrations to be seen as a rival worm and thus simply get attacked. Dec 19, 2022 at 23:41
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    @Sebastian_H Kynes (father of Liet) explains it in the first book: "Now they had the circular relationship; little maker to pre-spice mass; little maker to shai-hulud; shai-hulud to scatter the spice upon which fed microscopic creatures called sand plankton; the sand plankton, food for shai-hulud, growing, burrowing, becoming little makers." All of this is part of how Kynes plans (and educates the Fremen about) terraforming Arrakis.
    – Luaan
    Dec 20, 2022 at 12:46
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    Which suggests that the sand plankton ARE microscopic makers themselves. sand plankton becomes little maker becomes shai-hulud spawns sand plankton. Not entirely unheard of on earth (some fish eat their own eggs, or rather those of others of their species, young Komodo dragons are preyed upon by adults, same with young crocodiles and cayman for example).
    – jwenting
    Dec 20, 2022 at 13:48

My recollection from the book and movies is the strong implication that the metabolism of the worms is based perhaps on nuclear reactions, not mere chemistry like that of humans and other terrestrial animals. That is, while we use hydrochloric acid and I suppose other chemical processes to break down and derive energy from organic materials, perhaps the sandworms can take certain, but not all, metals and other inorganic stuff, as well of course as organic materials, and derive energy using things like nuclear fusion (I realize this is sort of inconsistent with real physics) or some other process not understood completely.

Do we not see the interior of the worms, when their mouths are open, as being something like a furnace? Even if that furnace requires radioactive materials found in the sands of Dune to burn, that does not mean it is not hot enough to melt the metal of harvesters into plasma.

The worms are immensely strong in order to move their vast bulk under the sands so rapidly -- perhaps Herbert meant to imply (or maybe he actually says this) that the metabolism of the sandworm is fundamentally different from that of other animals humans have encountered.

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    Sources for this? (Note that iron - and nearby elements - would be fuel for neither fission nor fusion reactions, so the mass of the harvester is still probably indigestible.)
    – DavidW
    Dec 19, 2022 at 13:44
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    Oxygen factory sounds chemical to me -- I sure would like to find the nuke reference because as mentioned, i think i recall it too.
    – releseabe
    Dec 19, 2022 at 21:04
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    @RIanGillis Their insides are compared to a blast-furnace. It's implied it has something to do with how the sandworm deals with the friction heat produced while the sandworm moves through the sand; it might very well be that the oxygen the worm produces comes from the dissociation of the silicon dioxide in the sand. It's never hinted in the first six books as being anything else than a chemical reaction as far as I can tell. It's of course quite implausible that the worm could survive such heat and accumulate that temperature, not to mention fuel all that with its food, but other than that...
    – Luaan
    Dec 19, 2022 at 22:14
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    Maybe the worms just spit it out later, like owls. Or it just passes a little rough. If we're speculating, then we've lost track of the worms' ultimate purpose: a plot device.
    – user15742
    Dec 20, 2022 at 17:46
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    @frеdsbend: if u are blind and just eat whatever is in front of you, i am sure you would have a mechanism to deal with large, indigestible things.
    – releseabe
    Dec 20, 2022 at 17:56

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