Karst ecosystems often support unusual or rare plant and animal species, both on the surface and underground. Certain species of ferns and mosses prefer or, in some cases, require a limestone substrate on which to grow. Other fern species have adapted to growing in the cool, moist twilight conditions of cave entrances.

Many wildlife species use various karst features for habitat. Caves are used intermittently by large carnivores for shelter or resting. Birds and small mammals, such as woodrats, often nest in caves and other cavities. Elk and deer commonly bed down in the vicinity of cave entrances during summer when the air from caves is cooler, and during the winter when cave air is generally warmer than surrounding temperatures. Caves, and their stable environments, can be critically important habitat for bat species that depend on them for roosting and hibernation.

Some karst-dependent species, known as troglobites, have evolved to living exclusively in the total darkness of caves. In BC, the only troglobite identified to date is a freshwater crustacean found in underground pools in caves on Vancouver Island. More common are troglophiles, which are species found living both inside and outside caves. Some individual troglophiles may complete their entire life cycle within a cave, while other members of the same species live their lives outside caves. Examples of troglophiles in BC include certain species of salamanders, spiders, and crickets. (Illustration by M. Nyhof.)