I am designing a monster that is as large as a continent. It flies across the planet very slowly and has basically a snake form. Life cannot exist on the planet's surface so the animals are drawn to the "snake".

What draws a ecosystem to its surrounding and how this happens? Can humans build houses and villages on him?

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    $\begingroup$ It depends on how wiggly he is. $\endgroup$
    – Willk
    Commented Sep 3, 2018 at 20:38
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    $\begingroup$ Discworld immediately comes to mind. We'll need a bit more information about this being. Does it move? How often and how fast? Does it have a rigid shell? How does it get nutrition? Does it breath? Poop? $\endgroup$
    – Schwern
    Commented Sep 3, 2018 at 20:40
  • $\begingroup$ Yes it moves. Very slowly around the world. It basically has a snake form. $\endgroup$
    – Payuka
    Commented Sep 3, 2018 at 20:48
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    $\begingroup$ Hmmm... we need to narrow this with more info. Such a creature would destroy any land-based ecosystem if it moved across land. As it moved through the sea it would create world-spanning tsunamis. It would massively interrupt atmospheric conditions when it moved, too. Unless the creature never moves, its existence would be antithetical to all life. Are you looking for land-based ecosystems? Sea-based? On its back-based? Right now the question is very broad and somewhat unclear. $\endgroup$
    – JBH
    Commented Sep 3, 2018 at 20:56
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    $\begingroup$ @Payuka, thanks. Could you edit your question with those changes? It's actually difficult for people to read through comments to find changes. $\endgroup$
    – JBH
    Commented Sep 3, 2018 at 23:27

4 Answers 4


While we could talk about worlds on the back of a giant turtle and similar things, let's explore some other options with "continental scale creature" with its own ecosystem and villages on top.

A clonal tree colony

Pando is a clonal colony of quaking aspen trees covering 100 acres estimated to be anywhere from 10,000 to 1 million years old. It's basically like grass, all the trees share a common root system.

One could imagine a continent dominated by a single clonal colony of giant trees. Animals and plants would live in this "forest". Humans could live in or among the trees, or harvest them.

Leviathan islands

Imagine a world with a vast ocean. There are large floating island chains. These chains are really ancient, continent sized leviathans. Each island in the chain is a part of it that sticks above water. They float just below the surface on ocean currents, filter feeding from the rich life just below the surface of the ocean. Over millennia, debris, flotsam, its own excretions, and mineral deposits have formed on its upper surface to create soil.

Humans who encounter these islands may not even know they're creatures until someone dives deep enough to get below it. Or until someone digs deep enough and agitates the giant.

SCP-169 has elements of this idea in modern times. Note that while that particular SCP entry is SFW, the SCP wiki gets pretty weird. Lots of great ideas in there, but click around at your own risk.

  • $\begingroup$ The second suggestion reminds me of Xenoblade Chronicles 2. $\endgroup$
    – majestas32
    Commented Sep 5, 2018 at 22:59
  • $\begingroup$ There's something similar in Subnautica- just a bit smaller. subnautica.fandom.com/wiki/Reefback_Leviathan $\endgroup$
    – Karst
    Commented Jan 16, 2021 at 18:18

The good, the bad, and the ugly

Australia is basically 4,000 Km long and wide. I'm basically 1.75 meters tall and 0.3 meters thick. That's a ratio (as good as any) of 0.17, so I'm proposing that your creature is at least 680 Km thick (making it a tapeworm, not a snake).

Earth's atmosphere is 480 Km thick. But most of it (e.g. 50%+) is in the first 16 Km.

The FAA mandates a minimum of 1,000 ft above everything in a 2,000 ft radius. Granted, that's for airplanes, which are less than 1% of the size of this critter. (A lot less, actually, but let's roll with 1%.) That means your critter needs a minimum of 30.5 Km. That's not very much, considering it's 680 Km thick, a burp may cause it scuff the ground.

Final number: the top of the creature is 230.5 Km into space. That's inside the range of low orbit. The bottom line is your critter probably has a snorkle descending into the lower atmosphere through which it breathes, and typhoon-force winds happen around the opening of the snorkle. Heaven help the good folks underneath it when the critter sneezes.

That was the good, now let's talk about the bad

I haven't done the math, but I expect the mass of this creature given its proximity to the planet will cause tidal changes and tectonic shifts. The world will literally reach up to the creature. Probably only by feet (maybe a dozen or so), but it'll be enough to fracture fault lines, cause minor eruptions, change currents, and basically make life on the planet itself something of a hassle. You said in a comment that you didn't expect life to exist on the "floor," so this might not be as bad as it sounds.

Aaaaaand the ugly

The problem is that the creature won't have enough mass to generate significant gravity. Especially in comparison to the planet below it. Since the top of the creature is in low orbit, you can't build anything on its back unless you have dome technology and can mine oxygen from its skin (mining the creature would be big business, btw... humanity being less pestiferous than bacteria is to humanity). And you can't build on the bottom, either, since the planetary gravity will simply pull you to the ground.

You would, however, have cliff-dwelling birds making nests in every fold of skin or everywhere they can make a bit of mud stick.

Creatures of this size tend to be very impractical unless you're in the mood for full fantasy — in which case you simply declare it to be so and have fun. (I love Terry Pratchett's work, BTW.)

  • $\begingroup$ The elevation issue might be ameliorated somewhat by the way the creature would sink into the planet... $\endgroup$
    – Joe Bloggs
    Commented Sep 5, 2018 at 20:43
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    $\begingroup$ @JoeBloggs :-) OK, that's a good point. $\endgroup$
    – JBH
    Commented Sep 5, 2018 at 20:52
  • $\begingroup$ I kind of like the idea of mining the giant snake we all live on. Interesting visual. $\endgroup$ Commented Sep 6, 2018 at 23:56
  • $\begingroup$ Gas giants have incredibly thick atmospheres- maybe this creature lives on one of them, not a rocky planet? $\endgroup$
    – Karst
    Commented Jan 16, 2021 at 18:21

Every macroscopic plant and animal has an ecosystem of microscopic life living on and in them. You have billions of bacteria, viruses, and fungi living on and in you. Some animals including some people, have macroscopic multi celled parasites and pests living on and in them.

So a creature a lot smaller than your example would have an ecosystem living on and in it.


That was featured in the National Geographic speculative biology "Alien planet". Darwin IV is home to a gigantic creature known as the Groveback. As its name suggests, it has a grove of trees on its back!

The Groveback absorbs nutrients from the soil. The trees absorb the nutrients and generate sugars and complex molecules via photosynthesis. These, in part, feed the groveback. And, wherever there are trees, there are animals feeding on them, fungi feeding on leaf litter, and the list goes on. You have an ecosystem.

Now to your "snake": it is too big to fly via wings. Think of a lighter-than-air gas filling its interior. This gas may be breathable to some creatures, plants and other things living inside it. Now, make the upper body skin more translucent. The inner cavity has a breathable atmosphere (maybe Hydrogen) and receives light. It gets waste products from the giant creature and recycles it. (Think of corals and the algae living inside them. They recycle waste products to feed the corals). Some of its product feeds the creature. The creatures may evolve a way to venture and look for such a "snake" and dig its way inside. When two or more snakes congregate, hopping from one creature to the next is easy.

A side note: If life cannot exist on the planet, how do those snakes live?


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