Sandworm

The sandworm was the giant animal that inhabited the deserts of Arrakis, the planet known to its native Fremen as Dune. It was the predominant lifeform of that world, at once honored and feared, and was the essential factor in the creation of the spice melange. They lived beneath the vast dunes that stretched across the surface, and Frank Herbert never says where the species came from. The Fremen called the creature the Maker and Shai-Hulud, and among the few peoples who had ever achieved any mastery over the beast, only they could ride it. (Dune; Dune (appendix))

The expanded books show worms already on Arrakis before the Butlerian Jihad ended, in the time of Selim Wormrider. (Expanded books: Dune: The Butlerian Jihad)

Physical characteristics#

The sandworm could grow to an enormous size by any standard. The physician Wellington Yueh cited specimens up to 450 metres long observed in the deep desert. (Dune)

Its skin was thick, rough, and semi-metallic, serving as armor and comprised of many overlapping, interlocking scales, each a few feet across, which protected the worm against the invasion of sand into its softer interior. A sandworm's internal workings resembled a massive blast furnace, producing intense heat and flame, and this combustion supplied oxygen to the nearly plantless surface of Arrakis. The mouth, positioned at the forward end of the creature, could easily consume objects as large as spice harvesters. A strong, flinty, cinnamon smell exuded from the beast, especially from its mouth, and it was often said that a worm could be smelled before it was seen. (Dune)

The sandworms were territorial, each holding its own stretch of desert against intruders. (Dune)

Behavior and diet#

Sandworms lived beneath the sand and were drawn to rhythmic vibrations on the surface. They would breach in pursuit of the origin of such vibrations in an effort to defend their territory, of which they were highly protective. For this reason, to see a worm and live to tell of it was extremely rare. The main component of the worm's diet was sand and the other inorganic, dry components of the Arrakis crust, and it was believed the creatures also sifted the sand-plankton for nourishment. Humans were not part of its diet, though there were cases of worms devouring people in the act of breaching, a fate Baron Vladimir Harkonnen alluded to when he intended for Lady Jessica and her son Paul to be abandoned to the desert. (Dune)

Water was fatal to a sandworm even in small doses. Water that entered the worm's body acted as a catalyst, accelerating its metabolism until it became unstable and its body gave out, a violent death. The rare stunted worm of the Minor Erg was a primitive form about nine meters long; one such worm was trapped in a water ditch and drowned, and the byproduct of the worm and water mixture was the highly toxic poison known as the Water of Life. (Dune)

Wormriding#

The armor of the sandworm, while all but impenetrable, could be exploited. By prying open the edges of one or more scales, the Fremen compromised the integrity of the armor, allowing sand to enter and irritate the worm's softer insides. The beast would then roll itself so that the opened scale was at the highest point from the desert floor, minimizing the amount of sand that could enter. A Fremen poised to mount the worm could climb aboard as it rolled the open scale upward, and so long as the scales remained pried open the worm would not submerge. Maker hooks were then placed toward the front of the creature to control its lateral movement. (Dune)

In this way wormriding became a viable and even sacred method of transport across the surface of the planet. A worm could be ridden until it tired and was allowed to submerge, so a long trip meant calling and mounting worm after worm. (Dune)

The spice cycle#

The creation of the sandworm began when sandtrout banded together after converging on a store of water deep beneath the surface of Arrakis. Water did occur naturally on the planet, but through this process it was always destroyed. The sandtrout and water mixture was converted into a liquid chemical that the worm could digest without being poisoned, and this chemical could erupt to the surface in a violent explosion known as a spice blow. The sandtrout that survived the event then coalesced and completed their metamorphosis into a young sandworm. Because the worm was essential to the creation of the spice melange, on a macro scale it exercised an enormous influence over the whole of humanity, whose commerce, space travel, and longevity depended on the spice. (Dune (appendix); Children of Dune)

Cultural and religious significance#

To the Fremen, the sandworm was a spiritual symbol of their faith, and they regarded the creatures as a manifestation of God. Within Fremen culture the worm bore several names beyond the Maker, chief among them Shai-Hulud, variously rendered as Old Man of the Desert, Old Father Eternity, or Grandfather of the Desert. Young sandworms were drowned by the Fremen to make the Water of Life used in the making of new Reverend Mothers, a ceremony central to sietch religious life. (Dune; Dune (appendix))

After the rise of the Atreides Empire and the spread of the Arrakis variant of the Zensunni religion across the known universe, reverence for the sandworm spread to other worlds. This continued under the rule of Leto Atreides II, who had himself become a hybrid of man and worm. (Dune Messiah; God Emperor of Dune)

Decline and survival#

The terraforming of Arrakis posed a grave danger to the sandworm, which found life outside the arid desert fatal. By the time of Leto II's reign the worms survived only in his desert preserve, the Sareer. At his death his body broke apart into sandtrout, each carrying a pearl of his awareness, and the desert began to return. (God Emperor of Dune)

By the time of Heretics of Dune, some fifteen hundred years later, Arrakis, now called Rakis, was desert again and the worms thrived once more. (Heretics of Dune)

The hostile actions of the Honored Matres later brought about the termination of all life on Arrakis, including, it was believed, the remaining sandworms. Before that destruction, however, Darwi Odrade and Sheeana had escaped Rakis with a single worm aboard a no-ship, covered by the last stand of Miles Teg. (Heretics of Dune)

On Chapterhouse, the secret base of the Bene Gesserit Sisterhood, the worm was released and broke down into sandtrout. They began turning that once-lush world into a desert where new worms and a new spice cycle could grow. (Chapterhouse: Dune)