The Rift and its caverns are filled with all manner of arachnid life, including: true spiders, scorpions, pseudoscorpions, harvesters, ticks, mites, wind scorpions, hooded tick spiders, whip spiders, vinegaroons and possibly even more
exotic variants. They range in size from less than a millimetre to a few dozen tonnes of bodymass. Usually the arachnids feed mostly on each other, though the smaller varieties (and some of the larger) can subsist off of the ambient heat, darkness, secrets and the very earth of the Rift-Continent, forming the basis of the ecosystem. Various ambush arachnids who are inactive for long periods of time also often supplement their carnivorous diet with thermosynthesis and lithovoria.
Some types of arachnids often swarm towards heat to feed on it, and the entire ecosystem instinctively hates light brighter than dim candles, and will go into a frenzy and attempt to destroy it if discovered. Cannibalism within species lines is common, and a wide variety of creatures beyond true spiders can also produce silk. Venom, especially venom that causes blindness or the rotting of the eyes, is also quite common.
There are also several plants within the ecosystem, though they all have a spidery appearance of strange arachnid leg looking branches and spidery shaped stems or trunks. These plants are primarily sundews and spidertraps, but also include broodplants that emit streams of ambulatory arachnid looking sub-plants to collect food for the main plant and spread their seed, and even some rare
flowering plants, with certain types of spiders feeding on their nectar and pollinating them.