Monster of the Week: The Sandworms of 'Dune'


Shai-hulud emerges... 'Spice Mass' by Luke Oram

"Now they had a 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." - Appendix I: The Ecology of Dune

Given that this week's podcast episodes revolve around the science of Frank Herbert's "Dune" universe, I thought it a perfect opportunity to explore the strange and puzzling biology of Shai-Hulud, the mighty sandworm home to the planet Arrakis.

First, let's refresh on what we know of sandworm biology from Herbert's writing. Shai-hulud is creature utterly unique to the planet Arrakis, tied to a complex life cycle on the desert planet. What's more, the psychedelic spice melange it generates plays a crucial role in the interplanetary civilization of the "Dune" saga.

These gigantic, sand-burrowing entities reach lengths exceeding 400 meters, widths of 100 meters at thickest point. In the deeper desert, they may even reach lengths of 1000 meters. Perhaps 1000 meters long in the deep desert. The typical worm consists of 100 to 400 segments, each possessing its own nervous system, but the head boasts a wide, toothy maw capable of swallowing whole spice harvesting operations whole.

In reading "Dune" and its sequels, you begin to feel as if you know a great deal about the sandworm, so it's a little shocking to realize some key omitted information from Herbert's writing. We're never told:

  • Whether sandworms lay eggs (to produce sandplankton).
  • Whether they are male and female.
  • How reproduction occurs AT ALL.
  • How it moves.
  • What it eats.

So we're left to infer a lot about these desert leviathans. Luckily, we have two excellent sources for possible explanations: 1984's "Dune Encyclopedia" and 2007's 'The Science of Dune.'

The Dune Encyclopedia Explanation

Contributing writer Maureen A. Shifflett takes a wonderful crack at the sandworm biology, fleshing out an entire metamorphic life cycle that explains many of the mysteries surrounding their violent ways.

For starters, she defines them as pure autotrophs: lifeforms that are able to form nutritional organic substances from simple inorganic substances. In other words, the worms barrel along through the sands, generating an electrostatic charge differential to power the biological transformation of inorganic compounds from their environment into biological components.

If they essentially eat nothing, then what's with the teeth, right? Well, Shifflett rather elegantly explains them as weapons for intrasexual combat among male sandworms. When two of these titans meet, they wrestle and writhe, employing their teeth to pull back each other's segments and expose the sensitive underflesh to sand irritation -- the very principle employed by hook-wielding Fremen worm riders.

And yes, I said male sandworms, because her model for shai-hulud defines it as a sexual species with both large males and smaller females (a mere 80 meters in length). Here's how it breaks down:

  • The secondary worm segment contains each individual reproductive system.
  • At age 1000, the female develops an egg sac in her reproductive system, constructs a deep, massive nest and then attracts a male with rhythmic thumping.
  • A male arrives and consumes the smaller female, then goes into a dormant state.
  • During this state, the heavy-duty spice fiber egg sac remains intact and is fertilized by the male's reproductive system.
  • When the male sandworm comes to, he vomits up the fertilized egg case and takes off.
  • This egg case eventually hatches into legions of sandtrout.

It's a lovely explanation that, again, roots well into what Herbert tells us about worm behavior. In real life, however, we don't have anything exactly like it. Sure, many female insects practice sexual cannibalism, but the consumption of the male isn't the reproductive act itself. The closest we have is the female angler fish's absorption of the male angler fish, a bizarre adaptation explored in a previous Monster of the Week post. If we view this act of sandworm cannibalism more as a merger, everything meshes a a little better with terrestrial biology.

(via Dune Encyclopedia)

Anyway, Shifflett's sandworm model continues:

  • The sandtrout are water scavengers, traveling great distances to bring water back to the nest site -- sometimes joining their bodies to transport the water.
  • Here, water mixes with excretions to form the pre-spice mass. CO2 builds up as a byproduct, resulting in a "spice blow" explosion that blasts melange up to the surface.
  • At this point, they enter a pre-metamorphic stage, during which surviving sand trout joined bodies.
  • As metamorphosis set in, each sandtrout (AKA little maker) becomes a segment and the conjoined body becomes that of a small sandworm. Over the next 1050 years, segments differentiate into head, reproductive segment, etc.
  • During this time, if environmental conditions were not met, the undifferentiated segments could revert to sandtrout.
  • Finally, the asexual juvenile worm develops. 20-30 meters long. This is the form Fremen capture and drown to produce spice essence.
  • Most juveniles become females, while the environmental absence of a male may resulted in male development.

Whew! I realize that's all a bit involved, so hopefully the inclusion of Shifflett's chart helps. And, by all means, pick up a used copy of "The Dune Encyclopedia" for yourself for more in-depth study. I'm merely hitting the high points here.

The Science of Dune Explanation

In her "The Science of Dune" chapter "The Biology of the Sandworm," biologist Sibylle Hechtel PHD creates an excellent model for shai-hulud biology based entirely on actual terrestrial systems -- namely that of the fungi-cultivating leaf cutter ants.

(Bryan Mullennix/Getty)

Simply put, she has to explain these deep-sand organisms (sandtrout) and their ability to create a highly potent psychedelic compound -- a compound that then blasts to the surface and gets consumed and spread about by adult sandworms. She does this by casting sandtrout as spice farmers rather than spice producers. After all, they're already scavenging and sequestrating water. Why can't they also tend a melange-producing fungus around the heat of deep thermal vents?

So she argues for sandtrout communities as "a combination of leaf-cutting ant nest and hydrothermal vent community." In this case, sand plankton and sandtrout would subsist on living spice fungi and bacterial mats that grow around the vents. And to flesh this out a bit, here's how the leaf cutter ant scenario plays out in our natural world:

  • Ants bring leaf cuttings back to the colony
  • They filter out the bad cuttings, hand the good ones off to the farmers.
  • They munch the leaf cuttings down into a fine mulch.
  • The ants grow delicious fungi on that mulch, lay some eggs in it and enjoy.
  • Finally, they drag depleted leaf cuttings to the dump chamber along with all the dead ants and dead fungus.

It's pure farming, and the leaf cutter ants have even manged to domesticate their crop, extinguishing it in the wild over 50 million years.

Hechte's model is also great in that it arbitrates the creation of spice to fungi, which create a great number of the exotic compounds found in our natural world. Granted, none of them allow you to see the future, but who knows what might evolve in a distant alien ecosystem?

Monster of the Week is a - you guessed it - regular look at the denizens is of our monster-haunted world. Sometimes we'll focus on the cultural aspects, but mostly we'll look at the possible science behind a creature of myth, movie or legend. Be sure to explore the Monster Gallery as well as the Monster Science video series.


About the Author: Robert Lamb spent his childhood reading books and staring into the woods — first in Newfoundland, Canada and then in rural Tennessee. There was also a long stretch in which he was terrified of alien abduction. He earned a degree in creative writing. He taught high school and then attended journalism school. He wrote for the smallest of small-town newspapers before finally becoming a full-time science writer and podcaster. He’s currently a senior writer at HowStuffWorks and has co-hosted the science podcast Stuff to Blow Your Mind since its inception in 2010. In his spare time, he enjoys traveling with his wife Bonnie, discussing dinosaurs with his son Bastian and crafting the occasional work of fiction.