Shai-Hulud

Also known as Old man of the desert or Great Maker.

Larger specimens reach lengths exceeding 400 meters. The throat of the worm has been measured at 80 meters in diameter in the largest specimens. A set of 1,000 or more organic carbo-silica crystal teeth surround the mouth in a circular pattern.

The adult worm is made up of 100-400 segments. Each segment possesses its own primitive nervous system. Respiration is accomplished through pores in the tough silvery-grey outer skin. There is no circulatory system as such, since most of the nutrients are in the form of gasses. Each segment has a series of membrane "baffles" to absorb nutrients. Water is fatal to a sandworm, even in relatively small doses.

The Fremen use sandworms for transportation, riding them great distances. Sandworms travel at an average speed of between 10 and 30 miles per hour. When ridden by Fremen, they are goaded into travelling at speeds upwards of 50 mph by continuous beating on the worm's tail segments. A large sandworm, goaded by Fremen, has a range of approximately 450 miles before it stops due to exhaustion. Consequently, distances on Arrakis are often measured in "thumpers" — the number of sandworms that need to be captured in order to make the journey. A "three thumper trip" would be approximately 1300 miles.

Shai-hulud's two attacks consist in his "bite" and his "trample". A sandworm is attracted by any rhythmic noise and will usually rise from below the source of the sound and swallow it.

Standing too close to a sandworm as it passes might cause one to be pulled down into the sand. Roll vs. DX to avoid. On a failed roll treat as per suffocation (p. B91) as the victim is pulled into the swirling sand beside the worm. Sandworms can be detected up to 25 miles away from the air, and can be detected up to 6 miles away when one is standing on the surface of the sand. This gives one some time to move to safety before the attack.

Holtzmann shields drive sandworms into a frenzy, and even a small personal shield operating on the surface of Arrakis will call worms from miles around. Worms attracted by a shield will not be distracted by anything else until they have destroyed the source.