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I read online that a Sandworm can grow to 450 meters long, and there are legends of worms up to 1000 meters long. The same article also stated that Sandworms are territorial and so will claim an area of desert as their own.

That got me to thinking, just how big is the planet Dune in comparison to Earth and has anyone worked out from its size how many sandworms could be present on the planet at any one time?

Spencer
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Richard C
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    As they are often used for transport over long distances,I think the population is quite high; from the books, a simple thumper put anywhere will call a worm quickly. – Max Feb 18 '20 at 12:08

2 Answers2

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1.6 Million*

The only real information we have to go on is a line by Dr. Kynes about the size of a worm's territory. From Dune:

“Big ones may control three or four hundred square kilometers. Small ones—”

According to the non-canonical Dune Encyclopedia, Arrakis has a radius of approximately 6,128 km, giving it a total surface area of 4.72×108 km2.

So, as a really rough estimate, let's make a few assumptions:

  1. Dr. Kynes never finished his statement, but lets say for argument that an average-sized worm's territory to be 250 square kilometres.
  2. Fifteen per cent of Arrakis' surface is inaccessible to worms (the Imperial Basin, the "wormline" surrounding the north pole, rock outcroppings, etc). This would leave a "worm-friendly" surface area of approximately 4.012×108 km2.
  3. Let's exclude altogether other stages of the worm lifecycle (sandtrout, etc), post-spice blow areas where they could be several new worms, as well as the "stunted worms" kept by the Fremen.
  4. We'll also ignore instances of contested territories and rare occurrences of multiple worms rampaging after shield generators and the like, and the fact that these territories are probably highly fluid and ever-changing as worms mature and move about.

Using our extremely broad reasoning, we could say that:

401,200,000 / 250 = 1,604,800 worm territories of average size.

StayOnTarget
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Vanguard3000
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    That is a great answer, thankyou. – Richard C Feb 18 '20 at 15:01
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    @Vanguard3000 However, the appendix to Dune gives the distance between two cities. The map of Dune in Dune shows those two cities. If one turns the line between the cities to north-south one can see how many degrees of latitude it covered. Thus one can calculate the length of a degree of latitude and thus the circumference, diameters, and surface area of Dune. I did that calculation once and found that Dune should be smaller than Earth's Moon. Which seems improbable but is based on more canonical sources than the Dune Encyclopedia. – M. A. Golding Feb 18 '20 at 15:53
  • @RonJohn: The radius of Mars is about 3400 km. It's a little smaller than Earth, though (6400 km or so.) – Michael Seifert Feb 18 '20 at 20:07
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    @MichaelSeifert Which makes sense; Dune mentions Arrakis' gravity being ~0.9, and its mineral composition seems similar. – Vanguard3000 Feb 18 '20 at 20:37
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    A gravity of 0.9 Earth's makes sense for something smaller than the Earth, yes. However, for something smaller than Earth's Moon, I'd expect a much smaller number. Probably more like 0.15 of Earth's gravity. – Mast Feb 20 '20 at 10:42
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    400 km² for a 1 km long worm is like 1600 m² for a 2 m human. Which is a 40 m x 40 m area. A little garden. Seems very crowded if the whole planet is divided up like that! You could never leave your small garden because it's surrounded by the small gardens of other territorial worms on all sides. – Daniel Darabos Feb 20 '20 at 12:01
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    While burrowing through sand seems per se improbable (it doesn't sound any easier or less energy-intense than burrowing through rock ... are sandworms nuclear-powered?), how deep is the Sea of Sand? Can you have several layers of sandworm? – David Tonhofer Feb 20 '20 at 18:52
  • @DavidTonhofer See this question: https://scifi.stackexchange.com/questions/69211/how-deep-are-the-sands-on-arrakis – RobertF Feb 20 '20 at 21:21
  • Liet Kynes only stated "Big ones may control three or four hundred square kilometers" - there may be large expanses of desert between core territories that are shared by worms. – RobertF Feb 20 '20 at 21:25
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    For such broad reasoning, I'd advocate keeping track of significant digits. If a worm's territory is 100–400 km^2, then guessing a figure like 250 km^2 means that you might be off by a factor of 2. That means your final answer could also be off by a factor of 2, so keeping the extra significant digits can be misleading. – jvriesem Feb 20 '20 at 22:28
  • @DavidTonhofer: Given that one of the byproducts of a sandworm's lifecycle conveys the ability to see through time and arbitrarily warp space: I think their power source is... plot... – Joe Bloggs Feb 21 '20 at 10:14
  • I like the fancy numbers. – Omegacron Feb 21 '20 at 18:22
  • @jvriesem: There are several other places where the margin of error is large. I would trust this final answer to zero significant figures. The order of magnitude is still reasonable. – Joshua Aug 06 '20 at 17:25
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To be technically correct, while being not at all helpful, at the time of God Emperor of Dune there was exactly one sandworm on Arrakis.

All other time periods, your mileage may vary.

Broklynite
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    And after the destruction of Arrakis, zero worms – Valorum Feb 18 '20 at 12:05
  • Wasn't there a few worms left during the time of the God Emperor of Dune for the spice for the Spacing Guild ? – Max Feb 18 '20 at 12:07
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    I've downvoted. OP isn't asking for the worm population at any specific moment but rather how many works can be present theoretically – Valorum Feb 18 '20 at 12:10
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    @Max no. The only spice in existence during this period was Leto's stockpile. – Daniel Roseman Feb 18 '20 at 14:16
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    @Valorum You just have to regard Leto as extremely territorial. The math still works out to 1. – Spencer Feb 18 '20 at 14:52
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    @Valorum the question's title and body conflict as to what he's asking: "Roughly how large is the population of Sandworms?", which is point-in-time vs "how many sandworms could be present on the planet at any one time?" – RonJohn Feb 18 '20 at 20:04
  • Don't forget the seaworms on buzzell – TheBatman Feb 18 '20 at 21:07
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    +1 for technically correct, the best kind of correct. – Sam Feb 21 '20 at 23:18