Subterranean Predators


I'm having trouble developing creatures that are cave dwelling and subterranean predators to provide some form of danger in the caves and abandoned mines of my World. With many high fantasy worlds such as Warhammer and Middle Earth, these creatures are often rat-men or goblins, however I am trying to do remain ultimately low fantasy in my style and was hoping if any of you fellow world builders could recommend any lists of underground predators that I could use as a base for a seemingly realistic species of Subterranean Predators.

Many Thanks, Geldor


One thing to keep in mind about subterranean dwellers is that their senses depend primarily on feel and scent, since the low or no light conditions that they live in mean that their eyes aren't very functional. If they live 100% underground and never go to the surface, then they wouldn't even need them.


I don't know much about real underground predators. But most of the ones I can recall at the moment are either harmless to humans, or small and poisonous, or something like toxic molds and the like.

You could try vampire bats, but they usually feed when their victim is asleep. Maybe carnivorous worms and grubs. Giant salamanders. Insect swarms. Poisonous newts.

Depending on how fantastical your world is, you could reimagine something like murloks to make them more 'animal' and less 'monster'.


Cave systems usually don't have enough resources to sustain larger organisms, so maybe go with something small...and swarm-forming. Like carnivorous albino beetles. *shudder*

Or you could go with carnivorous cave fish that swarm their victims, like piranhas.


Lately I've been rather fond of land sharks but that might be higher fantasy than what you're looking for. Other than that I would have to second the swam of carnivorous insects idea. I would also make them like the size of your hand. Not strictly realistic, but I think it would have more of an impact than regular sized bugs.
The scarabs from the Mummy movies sent a shiver down my spine, so anything that does swarm has a significant terror effect, possibly to a lot of people. If you are looking for predators that have higher functioning brains and create society then it wouldn't be hard to pick something and move it up on the evolutionary ladder to where it can function as a "evil" underground race.



Another way to go might be a forgotten race of humanoids that have adapted over the millenia to functioning well below the ground. Likely they'd be blind, or perhaps use something akin to clairvoyance to "see"; which could serve them above ground or below. They wouldn't even need their eyes; assuming they have any.

Another option might be to custom build a creature from the ground up; or at least gather inspiration from the real world so it somewhat feasible. Think of creatures in the real world that can survive below ground; Snakes, Lizards, Spiders, Felines, Rodents or whatever and customize their diet to whatever is found below the ground in your world.

In any ecosystem though you should consider the food hierarchy; which is usually, Food for herbivores, them below carnivores and them below omnivores. If you have giant rats, what do they eat?, maybe they are preyed upon by giant snakes that only pose moderate risk to travellers and they themselves (not to mention the rats) or are eaten by cave-dwelling sabrecats; ones that prey upon humans also. Maybe they too are prey, for a species of flightless subterranean dragon; small in comparison to other types of dragons so they can use at least most of the tunnels below ground. You never know, that is the beauty of designing your own ecosystem.
Try reading up about troglofauna/stygofauna - the scientific name for those albino crustaceans, arachnids, fish etc. They are kinda spooky looking and although they are generally small, if they ever got big I'd be freaking out!

For freak out factor, check out the scene in Peter Jackson's King Kong when they fall into the bottom of the ravine, and out come every kind of creepy crawly to feast on them - worms, crickets, spiders hooo boy :eek:

Caves are great fun; such a "hard science" setting to start with, so you can build a danger and an enemy out of how harsh conditions really are.

I agree, the hardest part of cave fantasy is working with how little food there is, if you don't want to say "they eat the same things dragons do." A couple of ideas might be:

  • Small cracks to the outside. Snakes, bugs or other things smaller than people can move outside to feed and then creep back in to lair. (One of the best traps I've read was in Barbara Hambly's Witches of Wenshar: a wizard had enchanted a small cave so that all the local snakes and scorpions were drawn to lair there.)
  • Underground rivers-- same thing, with killer fish or things that can swim in and then crawl through the caves.
  • Winged raiders-- another way creatures can get their food outside, if at least part of the cave system has an open roof. Bats or anything else can fly out, feed, and then nest in the cave again.
  • Fungus ecosystem. Say the cave's so rich in nutrients (probably from magic and/or waters from the outside) that it's thick with mushrooms, and sustains a whole food chain down there.
  • Fungus threats. You probably don't want "mushroom men" monsters, but what about nice simple fungi that give off a variety of spores?
  • Undead. Ghosts don't eat-- except maybe heroes' souls. :eek:

Or there are the really high-magic answers, things that live on rocks or stumble in from Portals To Hell. Or the beasts that someone keeps sending down there to guard it (or things sent down to feed the monster, as with sacrifices to the Minotaur).

And, I have to nod to one high-magic idea in Diablo 3: the idea that spiders are easy to magically mutate into giants but not to control, so they're perfect to leave to "guard" a cave (or forest, I guess) if you don't want yourself or anyone passing through it ever again. It really codifies how Tolkien and other authors use them, and what the classic spider does: it webs up a place and brings maximum terror to anyone trying to enter it.
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A quick search through a Monster Manual (D&D) reveals:

- undead creatures (especially if the underground area is near a graveyard) Skeletons, Ghosts, etc etc
- Aboleth (a horrifying creature... *shudder*) if you're unfamilar, google it, are plenty of resources than can help
- Ankheg (a big, giant predatory bug thats larger than man-size)
- Demons/Devils (there are plenty of extraplanar creatures from hell)
- bats (Dire bats, Giant bats, etc etc)
- some dragons live unerground
- and there are lots more... check out D&D Monster Finder :: Find monsters

Also there are plenty of sentient species who live underground - most notably Drow Elves. There are also Dwarves (who enjoy toiling away for bright gems and shiny gold), Azer (evil demonic Dwarves) Goblins etce
I think there's a horror movie called 'the descent' (or the cave or into the deep), where some poeple go down into into a cave, an earlier team of explorers had stranded inside the cave and they had mutated into creatures that used exholocation, due to some bacteria or virus that lived only in the cave.

You're going low fantasy right? Then my thought would be to simply increase the size and ferocity of cave dwelling critters. For the most part that would seem to be bats and rats. If it's completely black inside, bats have a huge advantage. All they need is some way to slice a victim open - claws on their wingtips? - and they can simply fly past, slicing in mid flight, and be beyond retribution range in a heartbeat. And rats can swarm and bite. Also their eyes may be more sensitive to IR. So they wait until a man's resting, then attack, bite and run.

Another thought occurs to me though there is no cave dwelling member. Big cats. Something good at hunting in the dark. Fast and with deadly claws and fangs. An ambush predator that creeps up and strikes from behind without warning. I'm thinking of something along the lines of a mountain lion. Not huge but terrifically deadly.

Cheers, Greg.
If you're being 'scientific'.
I echo BronzeOracle's post - the creatures in the crevasse are perfect.

They took a lot of existing creatures and made em bloody big - the large one feating on the guy's head is a Weta (in Joke for Weta studios) - which is a giant New Zealand cricket - it gets to several inches in size in real life.

The basic features of cave dwelling animals would be:

Blind - and not likely to be blinded by light either as they wouldn't have eyes and wouldn't even notice the light - that's a fallacy.
Long feelers/hairs - or echo location to navigate.
Cold bloodied (warm blooded creatures - e.g mammals/birds use too much energy to live perpetually in low energy systems like caves (Bats fly out at night and feed - so don't count)
Great teeth/claws/spines etc. - so if they do come across something and get hold of it - it can't get away easily. (Or another feeding mechanism such as stinging cells, stickiness etc that does the same job.

You do need an energy source in the cave somewhere - otherwise everything is feeding ultimately on only the detritus that drifts into the cave system.
This could be the rock itself (e.g. oils, or coal or something that can be metabolised. A heat source (such as a hydrothermal vent) or a gas (such as hydrogen sulphide) at the base of the food chain. (They've even identified a bacteria that can use electricity as an energy source). You could in theory even have a radioactive energy source as the energy source - there is evidence of naturally occurring radiaoactive piles in Africa Natural nuclear fission reactor - Wikipedia, the free encyclopedia

Whichever system you choose - this would allow bacteria to thrive, then something that feeds on those bacterial mats - then you have the basis for a food chain.