A project undertaken at Adelaide University, and supervised by Jessica Marsh
The Nullarbor Plain is one of Australia’s iconic natural landscapes. Beneath its flat surface lies an extraordinary underground world made up of thousands of caves, the largest arid limestone cave region in the world. The caves are important for biodiversity and are home to rare, cave-adapted species of spiders, and other invertebrates, many of which are found nowhere else in the world. These animals are specially adapted for life in total darkness: they often have no eyes, long limbs, loss of colouration (many are very pale), and other unique features. Caves habitats are some of the most fragile natural environments on earth. On the Nullarbor, there are a number of threats that are impacting the caves and cave-life, including feral animals, climate change and human activities, such as mining and development.
Long dead eyeless spider_photo credit Steve Milner
In early 2025, surveys of caves on the Nullarbor revealed a remarkable cave, which contained thousands of naturally mummified specimens of long-dead, cave-adapted invertebrates. These include spiders, cockroaches, centipedes, and the world’s only known eyeless cave-adapted wasp. These mummified animals are exceptionally well preserved, many look like they could have died yesterday, but they may be very old, possibly thousands of years old. Among the most remarkable finds are a number of complete specimens of a large, eyeless cave spider found only on the Nullarbor. Most species of spider in this group are extremely rare and are known only from tiny broken fragments, making these specimens especially valuable.
Most of the species found in the cave are undescribed and many are new to western science, with no specimens in museum collections. For such species, these remains are currently the only evidence we have that they ever existed. Some of them may already be extinct.
Together, the specimens offer a rare snapshot of an underground ecosystem that likely existed before humans began large-scale alterations to this landscape. Many of the animals in the cave appear to have died suddenly. Some were found partway up cave walls or hanging from the ceiling, frozen in mid-movement. We do not yet know what caused their deaths, or why no living animals have been found in the cave. It may have been the result of an event, such as a build-up of toxic gases, or due to the accumulation of lots of animals over a long time.
This project will study these specimens using analyses of ancient DNA held in the mummified specimens. Even though the animals are likely old, DNA may still be preserved, which will allow us to identify species, understand how they are relate to one another, and learn how they evolved over time. The team will also use radiocarbon dating to estimate how old the specimens are and to determine whether they died during one event or over a long time period.
The findings will help us build a clearer picture of the biodiversity of the Nullarbor, an area that is increasingly under threat. The research is expected to lead to the description of new species and provide important insights into past extinctions and environmental change. This information will be used to guide conservation efforts and decision-making on the Nullarbor Plain. By better understanding the biodiversity that relies on the caves, we can make more informed choices about how to protect these unique and fragile ecosystems while managing future development.
Ultimately, this project will strengthen Australia’s ability to conserve this globally significant landscape and the rare species that depend on it.