What is the giant sandworm in Dune?

Those unfamiliar with Frank Herbert’s novel Dune might be wondering what’s up with the giant sandworm in the first trailer for Denis Villeneuve’s Dune. Turns out this mysterious critter is secretly the movie’s main character — or at least the alien beast who first set its great conflict in motion. Here’s what you need to know about the planet Arrakis, and the giant monstrosities known as the “Shai-Hulud.”

Sandworms are native to the desert planet of Arrakis, and can’t be found anywhere else in the fictional galaxy created by Herbert. First described in the novel Dune, published in 1965, the sandworm were Herbert’s take on the “archetypical beast,” like the dragon in Beowulf. Dropping them on to a desert planet was born from his interest in environmental science.

“The interdependence in our own environment is quite sketchy,” he said in a 1969 conversation with The Dune Encyclopedia author Willis E. McNelly, “but we do know this: to create large bodies of sand, dust, whatnot, you need water, so I’ve set up multitudes of creatures who substitute for this [...] And I postulated that in one vector of their life circle, water is poison to them. We see this sort of thing on planet Earth right now where a creature can live in one environment, in one vector, but that environment will kill it in another vector. The anopheles mosquito is a good example.”

Another of the creature’s closest analogue is the annelid, a phylum that also includes the common earthworm. Like the common earthworm, the sandworms in Dune have segmented bodies and are fairly robust. Break off one of the segments, Herbert said, and sand worms can go on living. The only way to kill one is by electrocuting each segment individually, or by hitting the whole thing with a nuclear weapon.

Of course, unlike the varieties of annelid that you might use to bait fishing hooks, sandworms are a lot bigger. The largest portrayed in the original novel is more than 9,000 feet long and several hundred feet in diameter. You’d need a fishing pole at least as long as a Ningi is wide just to cast one off. Incidentally, they’re attracted to vibrations, making driving or even walking on Arrakis’ sandy surface particularly dangerous. That’s why most folks prefer to travel by ornithopter.

The Fremen — human natives of Arrakis — don’t have ornithopters, however. They’ve adapted to life with sandworms nonetheless. They tend to settle in rocky outcroppings where sandworms can’t penetrate. They also employ a seismic device known as a “thumper” to distract the creatures when the need arises.

Oh. The fremen also ride on sandworms.

Once on the surface, they use a wedge-like device called a “maker hook” to force a gap between two segments. That lets sand in, irritating the worm and preventing it from diving back down below the surface. With enough hooks the fremen can actually drive a sand worm around like a bus. It’s a great way to head into battle — especially when you and your friends are armed with giant blades called crysknives, made from the sandworm’s nearly indestructible crystalline teeth.

Are you grossed out yet? Well, I’ve got one more detail for you before you go.

As part of the sandworm life cycle, the creatures’ larvae produce a substance known as melange. Also called spice, it just happens to be the most important substance in the galaxy. The highly-addictive stuff both tastes and smells like cinnamon. Pound enough of it and it will give you prescience, longevity, and preternaturally blue eyes. Hang out in a tank of it for most of your natural life and you can move spaceships across the vastness of space using only your mind.

Not bad for worm poop. Not bad at all.