Monster ecology needn't be constrained by reality

Many bestiaries devote word count to describing the place of fantastical creatures within the ecology of the fantasy world they live in. Commonly, they are described in ways analogous to the animals of our own reality. They eat and procreate in the fashion of real animals, sometimes with a fantastical twist. All to often, however, these monsters feel less like monsters and more like cryptids or speculative alien biology projects.

The tendency towards what others have termed "gygaxian naturalism" has, in my opinion, robbed tabletop fantasy roleplaying of the fantasy portion. Fantasy is unconstrained by reality: the words are antonyms. There isn't anything wrong with cryptids and speculative biology projects, but they feel out of place in the fantasy genre due to their anchorage in reality. Even genetic engineering, a fairly science fiction-based concept, is commonly used as an explanation for monsters.

I don't advocate removing these ecologies, but I think monster makers should feel free to devise wholly fantastical explanations for why monsters exist that aren't grounded in modern scientific views of the word. For example, spontaneous generation! Among other things, it explains a fair amount of the weirdness typical of dungeons.

However, spontaneous generation doesn't need to be random. Even according to the original belief, creatures were only generated under specific circumstances. Grain turned into mice, rotting meat into maggots, the eggs laid by roosters and incubated by serpents or toads hatched into basilisks and cockatrices, people who died with unfinished business produced haunted houses, etc. Perhaps every animal is descended from an original that was generated spontaneously. Those few individuals that never formed a race of their own became the unique monsters of mythology.

Other possibilities include bizarre life cycles, more bizarre than is typical for fantasy worlds. Perhaps the medusa is the larval form of the hydra and the pegasus the male counterpart of the medusa. Perhaps goblins, hobgoblins and bugbears are the goblin equivalent of children, teens and adults, and maybe said goblins lay eggs that hatch into plants that produce fruit which hatch into goblins. Perhaps the heads of the seaweed siren occasionally sprout wings and fly off to become sirens of their own. Ironically enough this sort of thing is common in reality, mostly in the ocean, but rare in fantasy.

Indeed, a given monster may have multiple such origins. Think creatively! Maybe I'll write a few fantastical ecology articles myself...

ADDENDUM 10/26/2017
Relevant links:

• http://adventuresingaming2.blogspot.com/2015/09/spontaneous-generation-in-dungeon.html
• http://dmdavid.com/tag/3-reasons-science-and-ecology-make-a-bad-mix-for-some-monsters/
• http://grognardia.blogspot.com/2008/09/gygaxian-naturalism.html
• http://oldguardgamingaccoutrements.blogspot.com/2009/12/spontaneous-generation-allows-weird.html
• http://swordsandstitchery.blogspot.com/2016/05/two-great-free-old-school-resources-1d6.html
• http://valianttheywere.blogspot.com/2015/09/megadungeon-genesis-pit-upper-levels.html "A nifty little pit at the bottom of the dungeon that spawns zero level pcs."
• http://www.chimericalrealm.com/2013/01/kingdoms.html
• http://www.enworld.org/forum/showthread.php?308057-Spontaneous-Monster-Generation
• https://d-infinity.net/basic-system-xenogenesis-fantasy-settings
• https://1d30.wordpress.com/2009/11/19/dungeon-ecology/