The Tasmanian cave spider, or Hickmania troglodytes, is an obligate cave dwelling species that resides in Tasmanian caves among many other cave fauna. Tasmania is an island state located south of Australia.(Doran et al.1999) Tasmania is shown in red here next to Australia. File:Tasmania in Australia.svgTasmanian caves tend to be dark, damp, and humid. This spider is also found in places such as hollow logs or underneath building structures. They are an obligate cave dwelling species because if they are not in a cave environment they will likely die. (Doran et al.1999, Australian Museum, 2014, Tasmania Parks and Wildlife Service, 2014) This is due to the fact that they are troglophiles, which means that they have adapted to their cave environment by getting rid of their terrestrial adaptive features that restrict water loss in order to survive in the moist, humid, cave environment. (Doran et al. 2014) Examples of cave fauna that the Tasmanian cave Spider feeds on include crickets, millipedes, beetles, and flies. (Australian Museum, 2014)

            The Tasmanian cave spider can be found in the twilight zone, or entry way, of many caves in Tasmania. (Tasmanian Parks and Wildlife Service, 2014) The health of this spider as well as the rest of the cave fauna is dependent on the health of the terrestrial environment outside of the cave as it acquires nutrients from outside of the cave from streams and outside organisms. If pollution is brought into the cave from the outside or not enough nutrients are being brought in, this can negatively impact the organisms that live inside the cave. (Doran et al. 1999) Also related to pollution being brought in the cave, the ecosystem of a cave can also be disrupted by frequent cave tours and visitors. (Doran et al. 1999, Tasmanian Parks and Wildlife Service, 2014)

            The role of the Tasmanian cave spider in the cave is to represent the health of the outside environment and the cave. (Doran et al.1999) Since the spiders are usually located in the entrance of the cave, they are right in between the inside of the cave and the outside of the cave. (Tasmanian Parks and Wildlife Service, 2014) The Tasmanian cave spider is very sensitive to change in the environment. This means that when conditions on the outside of the cave are out of the normal or are not looking well the spider retreats further back into the cave or relocates within the cave. They sometimes will even leave their egg sacs if the environment becomes too uncomfortable. This serves as a signal to the rest of the cave fauna that the outside ecosystem has been disturbed and could soon affect the inside of the cave. (Doran et al. 1999)

            An example of how cave fauna are affected by the outside ecosystem is that the cave fauna in Tasmanian caves are put under a lot of stress and the cave ecosystem is negatively impacted when unexpected flooding occurs. When excessive flooding occurs during a time when flooding is expected to occur it does not affect the cave dwelling organisms very much. However, when flooding occurs during a time it is not expected to occur or does not occur during a time that it is expected to occur, it creates stress for these organisms. This can throw off their reproduction patterns. (Doran et al. 1999)

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