The heyday of cave faunal investigations in Australia was probably through the 1960s and early 1970s and a considerable body of information became available. In more recent years interest has re-awakened and a remarkable number of new discoveries have been made. Australia was thought to be fairly depauperate in its cave faunas but this has been shown to not be true. Some remarkably rich cave fauna occur in tropical Australia and in Tasmania. Bayliss Cave, one of the Undara lava tunnels, has recently been shown by Frank Howarth to contain 24 obligate cave dwellers - fully cave adapted species and more than twenty other species. Thylacine Lair at Bubs Hill contains over 55 species and Kubla Khan has been shown by Stefan Eberhard to contain 72 different animals.

The cave ecosystem is commonly divided into four zones based on the amount of light available. These zones are the entrance, twilight, transition and deep zones. Howarth’s work in North Queensland has revealed the importance of a fifth zone - an area where carbon dioxide is high. Highly specialised cave fauna are generally found only in the deep zone. The outer parts will have faunas resembling, or largely made up of surface species adapted to moist environments such as leaf litter. The zones will of course have an increasing stability as darkness increases to maximum and the influence of the outside world decreases.

The lack of green plants as energy sources means cave ecosystems are largely dependent on food being brought in from outside. The extreme adaptation of some cave animals makes for a very sensitive ecosystem. Low species diversity, together with low species numbers, are a recipe for a fragile ecosystem and even minor disturbances can have catastrophic effects. Energy sources are restricted to detrital material falling down shafts and steep slopes, to material washing in down streams and to material brought in by other animals including humans and, most importantly, bats.

Troglobites are totally cave-adapted (obligate cave dwellers). They are often white to translucent, very slender and with elongated antennae and legs and slow moving. These are the very sensitive species. A few years ago one would have said that only 15-20 species are known from Australia but this was due to the lack of researchers and observations by cavers. We now know that there are probably dozens of species in Tasmania alone. Recently Stefan has found a couple of very interesting, ancient species of troglobitic crustaceans whose origins probably go back to the supercontinent of Gondwana (Antarctica, Africa, South America, India and Australia) which finished breaking up about 90 million years ago (see adjacent press article). Similar syncarids are found in Tasmania, South Australia and in Western Australia. The first records of syncarids in NSW were from the New England area. There is a large group of animals called phreatoicids which are found in interstitial spaces in sands and gravels, these often closely resemble troglobites.