Sandworms are giant creatures found only on the
desert planet Arrakis. They are reverently called "Shai-Hulud" by the planet's indigenous
Fremen, who worship them as agents of God whose actions are a form of divine intervention. The Fremen also refer to the sandworms as "Makers".
Physiology Herbert describes sandworms as colossal terrestrial
annelids with features of the
lamprey. They have an array of
crystalline teeth which are used primarily for rasping rocks and sand. During his first close encounter with a sandworm in
Dune, Paul notes, "Its mouth was some eighty meters in diameter... crystal teeth with the curved shape of
crysknives glinting around the rim... the bellows breath of
cinnamon, subtle
aldehydes...
acids..." and in diameter, although Paul becomes a sandrider by summoning a worm that "appeared to be" around half a
league () or more in length. These gigantic worms burrow deep in the ground and travel swiftly; "most of the sand on Arrakis is credited to sandworm action". Water is poisonous to the worms, They move through the desert sands and ingest large quantities of
melange pockets to consume the
microscopic organisms known as "sand plankton" that inhabit it. These plankton eat melange which itself is a byproduct of dying sandworms. When consuming a melange mass, a sandworm excretes a more refined form of the melange as well as dispersing it across the desert environment, all this sustaining further plankton growth. stage of a sandworm are shown to be called "sandtrout", which the Fremen call "Little Makers". After exposure to sun and air, this mass becomes melange. The Fremen themselves protect their water supplies with "predator fish" that attack invading sandtrout.
Leto II says in
Children of Dune:
Behavior and function In
Dune, the desert of Arrakis is the only known source of the spice melange, the most essential and valuable commodity in the universe. Used as a drug, melange lengthens life span, increases vitality, and heightens awareness. It can also unlock
prescience in some subjects, which makes safe and accurate interstellar travel possible. The harvesting of melange is therefore essential, but is also a highly dangerous undertaking due to the presence of sandworms. Rhythmic activity as minimal as normal walking on the desert surface of Arrakis attracts the
territorial worms, which are capable of swallowing even the largest mining equipment whole. First, a worm is lured by the vibrations of a thumper device. When it surfaces, the lead worm-rider runs alongside it and snares one of its ring-segments with a special "maker hook". The hook is used to pry open the segment, exposing the soft inner tissue to the abrasive sand. To avoid irritation, the worm will rotate its body so the exposed flesh faces upwards, lifting the rider with it. Other Fremen may then plant additional hooks for steering, or act as "
beaters", hitting the worm's tail to make it increase speed. A worm can be ridden for several hundred kilometers and for about half a day, at which point it will become exhausted and sit on the open desert until the hooks are released, whereupon it will burrow back down to rest. Worm-riding is used as a
coming-of-age ritual among the Fremen, and Paul's riding and controlling a giant sandworm cements him as a Fremen leader. Paul also uses worms for troop transport into the city during the Battle of
Arrakeen after using
atomic weapons to blow a hole in the Shield Wall. After the reign of Leto II, sandworms become un-rideable. The one exception is a young girl named
Sheeana, an Atreides descendant who possesses a unique ability to control the worms and safely move around them. Fremen also use the sharp teeth of dead sandworms to produce the sacred knives they call
crysknives. Approximately long, these hand-to-hand weapons are either "fixed" or "unfixed". An unfixed knife requires proximity to a human body's electrical field to prevent its eventual disintegration, while fixed knives are treated for storage. Fremen tradition dictates that once a crysknife is drawn, it must not be sheathed until it has drawn blood. ==Storylines==