Let's assume for the sake of argument that:

  1. It's a 50/50ish split between new prey/predators herbivores/carnivores being introduced. So already a bit imbalanced.

  2. The creatures/flora make sense anatomically (abide by square–cube law, can get enough oxygen in their lungs, etc), but are still fantastical in scope or size, E.G a dragon.

  3. The world is completely or largely uninhabited by humans.

How do you guys think this goes down?

  • $\begingroup$ Please clarify your specific problem or provide additional details to highlight exactly what you need. As it's currently written, it's hard to tell exactly what you're asking. $\endgroup$
    – Community Bot
    Mar 9, 2022 at 8:03
  • 5
    $\begingroup$ I’m voting to close this Q because this is an off-topic and hypothetical high concept question that has no "right" answer (all answers are equally valid, see the help center) and violates the Book Rule (see again help center). There are examples of introduced imbalances on Earth were the introduced something died quickly, others that fell into balance, and others where the introduced something overwhelmed the ecosystem. $\endgroup$
    – JBH
    Mar 9, 2022 at 8:26
  • $\begingroup$ @AllThatIsAndEverWas To start off from new grounds, take some species you'd like to challenge (dragon for instance), describe it precisely (there are mmaaaannyy dragons : big, small, with red spots...), introduce them in an environment (e.g. : Amazon rainforest), and then ask "would it thrive". Or perhaps better "Would there be hinderance to their introduction with this new environment?". In both cases it'll be much more focused and answerable as we'd have much more elements to compute :) . $\endgroup$
    – Tortliena
    Mar 9, 2022 at 12:55

3 Answers 3


Utter destruction the moment it happens

At first I thought the question was too broad, but actually the answer will be the same however you approach it. If any and all fantasy flora and fauna is introduced, it'll simply destroy the planet. The simple reason is that theres just too many.

There's no restrictions on the flora and fauna introduced. With the unending amount of fantasy stories from both books as well as religion, There's too many that are introduced. Just of the top of my head I can think of 3 stories that have living planets. That is enough to destroy the Earth. Yet even without these the sheer amount of fantasy creatures is too many to count. The mass alone is probably a destructive force, if not just the sheer amount of food required to keep them alive. All nature would be devoured or simply destroyed before the day is out. If we include things like dragens and other dangerous creatures, even if they can only breathe fire once, will be enough to burn or otherwise destroy the planet.


Too many fantasy creatures will be introduced and destroy the planet.

  1. An imbalanced ecosystem is likely to collapse. So this "50/50ish split" will not remain for long. Either it will come to a balance or it will collapse.
  2. As long as the creatures/flora get their survival needs, they will survive. Size doesn't matter.
  3. If everything else is large, then humans may also be large to survive otherwise they will be at lower end of a food chain.

Collapse and Regeneration

The fantasy animals eat all the prey animals, collapse the food chain, and go extinct. In a few centuries things are back to before the conjunction, perhaps with some of the less fantastical fantasy animals slotting into empty slots in the food chain.

Real world animals are designed to be efficient. Most predator/prey encounters end with the prey noticing the predator and trotting off a few dozen yards. The predator then leaves and tries again later. Most hunts are unsuccessful and end early when the hunter gives up.

Typically the predator (Lion) runs about the same speed as the prey (Wildebeest) and is only just strong enough to kill them. Sometimes they are not strong enough and only prey on the old, the young, and the weak. This creates a predator prey balance.

Fantastical creatures are designed to be large and impressive. Dragons are big and strong enough to swoop over a herd of wildebeest and barbecque the whole herd for dinner, with little effort. They eat all the wildebeest, and make more dragons. But then there are loads of dragons and no prey left. The dragons starve.


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