How large of a shell would a World Turtle need to have to have most of the major types of biomes on its shell, including but not limited to swamp, jungle, temperate forest, and polar forest?

Also assume the different parts of the turtle can be eco-regions such as: legs, neck, tail, and head.

Assume the shell has a large mountain like ridge along its spine.

Gravity: Gravity pulls objects downward, not towards the center of the turtle

Water: Assume water comes from springs in the turtles shell, so no bodies of water larger than a lake

Air: Assume the air is thinner at higher elevations like on Earth, and that the atmospheric conditions are Earth-like.

  • $\begingroup$ I order to answer the question, I think we'd need to know, for starters: 0) How gravity works on your turtle (does it pull down relative to the turtle's orientation, or towards the center of the turtle?) 1) Why the air doesn't escape into space or fall off the edges of the shell. 2) How the water is recycled. $\endgroup$
    – Qami
    Commented Aug 22, 2018 at 21:07
  • 1
    $\begingroup$ This feels like a magical creature and I would recommend not looking too deeply into how everything has exist with real world rules. Its perfectly acceptable to have giant space world turtles with multiple continents and ecosystems as a framework for your world without needing to explain how they were brought into existence. It might be better to frame the question as, how large does a continent need to be to have these different biomes and throw that onto a turtle. $\endgroup$
    – Shadowzee
    Commented Aug 22, 2018 at 23:29
  • $\begingroup$ Terry Pratchett explored the worlds of astrochelonians in his disc world novels, and somewhat in the precursor novel "Strata" $\endgroup$
    – pojo-guy
    Commented Aug 23, 2018 at 2:41

2 Answers 2


How the sun interacts with the World Turtle is going to have a major affect on types and amount of biomes present, and thus, how much space is required to have a wide range of environments present.

Chile would be a good example of a small area with a wide range of climates. It has wide range of climates for a country with a relatively small area. This is because it's so long and thin it covers a huge range of latitudes.

You could achieve a similar affect on the World Turtle by having certain areas receive far more solar input than others. Therefore you could fit a wide climate range with a much smaller space.

As others have raised - the concept of a World Turtle is inherently magical, so no one is going to question if the biomes are perhaps supported and separated by additional magic.


If you want it to contain the biomes that are related to latitude, like tropics, tundra, and moderate, then at least the size of north America, which is completely impossible for a number of reasons.

If the turtle has an irregular shell with mountains and stuff, then the amount of room could be around this compact, but the shell might need to be significantly larger if the geological formations have to form on its back as well.


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