The bats live suspended from the roofs of the caves and their guano falls onto the cave floor, forming rich food for insects like beetles, mites, worms, cockroaches etc. These insects are in turn fed upon by spiders, crickets, centipedes, pseudo-scorpions and the like. And these creatures are then hunted and eaten by frogs and toads. Snakes also live in caves and the non-poisonous Cave Racer, Elaphe taeniura , is the only snake that has adapted to cave life and it feeds on bats, thereby completing the food chain. Bats are also useful to the life outside the cave.
Bats pollinate the durian and petai trees, as well as other fruit trees.
The bat guano is a rich fertiliser but the practice of collecting it should be discouraged as it disturbs the delicate ecosystem in the caves. Small mammals such as rodents can also be found in caves, also porcupines and occasionally elephants will visit a cave entrance, presumably to lick the salts there. But the main cave life is made up of invertebrates. This includes one of the world's rarest spiders, the Trapdoor Spider, Liphistius batuensis , aptly named after the Batu Caves. It is thought that this species is unique to Dark Cave as it has not been found anywhere else in the world.