Dune's monstrous sandworms are a constant threat living beneath the surface of the desert planet Arrakis, but the creatures feast on more than just people. A constant threat to the indigenous Fremen and off-world colonist alike, the sandworms are highly territorial creatures, first introduced in a scene where one devours an entire space harvester in the desert and nearly claims the life of the film's lead protagonist Paul Atreides (Timothée Chalamet).

Sandworms are also a vital part to the ecosystem of Arrakis including the production of the spice melange, the most valuable resource in the universe. Their long and mysterious lifecycles are poorly understood by the Imperium at the start of Dune 2021, but the Fremen understand that without the worms, there would be no spice. The Fremen truly highlight the importance of the creatures to the audience by worshipping them, but many viewers were also left with a number of questions about the nature of the enigmatic beasts. Why do they seem to prey on humans? What did they eat before crews of spice harvesters? And how do such enormous creatures survive in the barren wasteland of Arrakis' deep desert?

Related: Dune’s Sandworms Explained: Why They’re So Important

Contrary to what many might think given how they are depicted in the film, Dune's sandworms don't actually want to eat humans. In fact, the human body is somewhat poisonous to the colossal creatures. They also don't gain any nourishment from devouring the spice or the harvesting equipment. Instead, sandworms' diets are linked to the complex ecosystem of Arrakis—most of which occurs beneath the sands.

Dune Sandworm Chasing

Dune shows sandworms attacking human characters, but they don't deliberately pursue people as prey. Sandworms have a strong aversion to water because it acts as a poison that destroys their metabolism. Enough water can even kill them. Humans, being roughly 60% water, actually present a huge risk to the worms and at best severely agitate their systems when consumed. The only reason sandworms pursue humans is that the rhythmic vibrations caused by their movement simulates those of native Arrakis prey that would be more suitable. This is why the Fremen demonstrate a unique method of walking across the planet's surface that emulates the free-flowing movement of sand and removes any rhythmic pattern from the individual's gait.

The sandworm's diet of choice is also largely unrelated to the spice that makes Arrakis such a key planet in Dune. Instead, the worms feed on microscopic sand plankton that exist throughout the desert planet. The plankton feed on traces of melange in the sand which can create the illusion that sandworms are drawn to the spice, but they are actually only interested in the plankton. Sandworms also feed on the native desert creatures which have low enough water content to avoid any danger to the worms. Dune lore also mentions sandworms feeding on other, smaller members of their species, but they avoid eating sandtrout which create the spice and eventually grow and evolve into young sandworms.

Dune's sandworms are the most dangerous predator on Arrakis, but only due to the missteps of the colonists. They can be deadly to harvesters, but the Fremen have mastered coexisting with them, and they are vital to the creation of the spice melange in Dune. Likely the most important non-human species in the series, the creatures stand as a symbol of the dangers of colonization and misunderstanding other cultures. Given that they play such a significant role in the workings of the Imperium, there's little doubt that the sequel to Dune will explore the mysterious sandworms even further.

Next: Dune: What Sandworms Look Like In Every Adaptation

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