Name: Could a "Dune" Sandworm Exist in Real Life?
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Sandworms are a staple of sci-fi. But there are ecological and evolutionary limits to consider when deciding if a species like that featured in Dune could actually exist.

There are ecological and evolutionary limits to consider.

Sandworms are a staple of sci-fi. But there are ecological and evolutionary limits to consider when deciding if a species like that featured in "Dune" could actually exist.

Could a "Dune" Sandworm Exist in Real Life?

There are ecological and evolutionary limits to consider.

Evolution

Could a Dune Sandworm Exist in Real Life?Published: December 2, 2021Narrator: Sandworm-like creatures of all varieties have long slithered through science fiction and fantasy—including Tremors, Beetlejuice, Star Wars: The Empire Strikes Back, The Mandalorian, and even SpongeBob. Yes, I know that’s not sci-fi, but Bikini Bottom is pretty fantastic if you ask me.Now sandworms are back, shaking things up on planet Arrakis in the 2021 movie Dune, based on the 1965 sci-fi novel by Frank Herbert.Jeremiah Smith: I think the main thing that you notice about the sand worm is that they're huge, right? [laughs] But they're also, you know, incredibly ugly. I wouldn't want to see one in real life.Marianne Bronner: I read Dune when I was a teenager, and I don't remember very much about the book itself. But I do remember the sand worm because it was huge and scary and ugly.Narrator: Is there any science to this fiction?According to the fandom wiki page, sandworms in the Dune universe could grow to about 1,500 feet. That’s over a quarter of a mile! For comparison, Earth’s largest animal, the blue whale, is “only” about 80 feet long.Jeremiah Smith: That's common in sci fi, right? They don't they don't have to follow the rules of physics, necessarily, so animals could be as large as they want them to be.Narrator: More on that point later. Meanwhile, here on Earth, we do find species with a shape resembling sandworms. There are lampreys—with rows and rows of scary teeth—but they’re tiny in comparison. These jawless parasitic fish grow to about 24 inches as adults.Bronner: So even though they're scary and they have these horrible mouths, they are not going to be quite as scary as a sand worm that would be much bigger than the size of this room.Narrator: Worms on Earth have a similar body plan, and they come in many sizes.Paul Sternberg: So the worms I work with are a millimeter long, which is just barely visible to the naked eye. But some of the roundworms are 10 feet long. So I think they can scale quite a lot.Narrator: But unlike lampreys, which have a skeleton, worms are invertebrates.Estefania Rodriguez: Invertebrates are a group of animals that are characterized because they don't have a spine or bones. They are a very, very diverse group of animals and they make up almost all the animals on this planet, 97 percent.Narrator: And just because a worm is long, doesn’t mean it’s big.Felisa Smith: There's something called the African giant earthworm, which sounds terrifying. And it is in fact 7 meters long, which is huge. But it's only an inch thick.Narrator: So how realistic are these sandworms? Is there a maximum size animals can be before the laws of physics and biomechanics become too constraining?Felisa Smith: If you're a terrestrial animal and you're a vertebrate, you have to be able to walk around. And so it has been estimated that about 140 tons is the maximum size you can be before the width of your legs, basically, are so big that you can't walk efficiently, right, because they would hit each other. In oceans, of course, you can swim.Narrator: Marine animals can be much larger because they're buoyed by the water and thus don't have to support their own weight all on their own.Felisa Smith: The blue whale is the largest organism that's ever been in the oceans as far as we know and it's on average 160 tons.The problem you have with the sandworm is that it's a tube, essentially. As the tube’s diameter gets larger, the walls have to get thicker and thicker and thicker to be able to support it. So to make the sandworms that big, you'd have to have incredibly thick walls. There wouldn't be much space for anything else.The other problem you have is that it turns out that if a muscle is twice as big, it's not twice as strong, it's less than twice as strong. And so that means that the efficiency of using muscle gets worse as you make it bigger.Narrator: Ok, then let’s hypothetically say we can add something to our sandworm so that it can support itself.Felisa Smith: Well, you could put an exoskeleton, but we know that they have to be really thick to support the inner part and so that's not going to work. You try to put an internal skeleton? Well, then you've got no space and the thing weighs so much you can't move, right? So it's basically a giant thing lying there.Narrator: Then there’s the question of how the sandworm breathes while it’s under the sand’s surface.Felisa Smith: So if it's an earthworm, it's breathing through its skin and so if you make it too wide, it can't diffuse properly. Which is why the largest earthworms on the planet are still only an inch wide, so that oxygen can diffuse.Narrator: But imagine our sandworm can somehow support itself and breathe underground. To visualize how Dune’s sandworm might move through sand we turn to animals like the sandfish skink and the shovel-nosed snake.Creatures like these “swim" just under the sand’s surface. As these animals move, they create a series of undulating waves that press on the sand around them, creating a net force forward which propels them through sand and overcomes forces like friction.Sternberg: The other way is just to ingest, like the earthworm method of just going in and taking everything in.Narrator: You heard that right. Earthworms can dig tunnels by eating the soil that’s directly in front of them and then pooping it out, along with mucus to form the walls of their burrow. This raises some additional questions about sandworm biology.Sternberg: The worms that we study in the lab, they poop every minute. So I guess I'd also want to know how that works in a sandworm. If you get eaten by one, what's the chance of getting out alive?Narrator: Speaking of which…Felisa Smith: What the heck is this thing eating?Narrator: The movie Dune shows Arrakis as a barren planet. Although they do eat sand plankton—and the occasional spice harvester—they’d need A LOT more food to meet their energy demand.Felisa Smith: You're talking about an animal that's many times the size of a blue whale. So where is this food, right? I think you'd have to be swimming in a sea of phytoplankton and not a sea of sand. As far as I know, that wasn't part of the Dune universe.Narrator: If atmospheric conditions could support a sandworm, then we’d be creating circumstances where it would be difficult for humans and sandworms to coexist.Felisa Smith: If the oxygen is higher, it does get easier for respiration to occur because the oxygen can penetrate deeper into the body. But it's also true that high-oxygen environments are flammable. You know, a spark and it's just going to explode. You're putting together a set of circumstances where people would not be walking around with the sandworm.Narrator: So it’s not impossible to have sandworms—but they’d have to be much smaller and it would help to have a plentiful food supply wandering by. It’d be kind of like the bobbit worm that lives on the seafloor.

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