In the dry, flat stretch of Australia’s Nullarbor Plain, where the horizon seems endless and life appears scarce, a hidden underground world is rewriting what scientists know about evolution, extinction, and the fragility of ecosystems. 

A team of researchers from the University of Adelaide, working alongside expert cavers, has discovered dozens of bizarre, eyeless, cave-dwelling invertebrates, including the world’s only known blind cave wasp, mummified and preserved in a cave in Nullarbor. 

These ancient, long-dead creatures, along with a newly found living spider species, offer an extraordinary glimpse into life in complete darkness and isolation. 

“The cave contains thousands of such invertebrates. Many of the invertebrates we discovered are new species, and some might already be extinct. The age of the specimens is not currently known – they could be dozens of years old, they could be hundreds, they could be many thousands,” Jess Marsh, lead researcher and a faculty member at the University of Adelaide, said. 

Finding a whole new world inside a cave

In April of this year, Marsh and her team led an expedition deep into the caves beneath the Nullarbor Plain, a region that hides over 250,000 square kilometers of limestone caves formed by ancient seas. The mission involved crawling over 1.5 kilometers (~ one mile) through tight passages, dusty sediments, and steep drops, all in total darkness. 

“The long journeys into these caves were incredibly challenging—filled with tight squeezes, a lot of time spent crawling, and belly-wriggling through dusty sediment, plus a few nerve-wracking heights. But I would repeat it in a second,” Marsh said.

They were searching for signs of cave-adapted life, organisms that have evolved over generations to survive in harsh, lightless environments. Their search led them to a cave with thousands of mummified invertebrates. The conditions in the caves —dry, salty, and undisturbed —had perfectly preserved their bodies. Interestingly, these creatures hadn’t simply fallen and died. Some were discovered halfway up cave walls, frozen mid-climb.

The most striking finding, though, was a completely blind cave wasp, unlike any that had ever been found. This species has no working eyes, extremely reduced wings, and elongated legs and antennae, features that help it navigate a world with no light. This is the first known eyeless wasp species on Earth to evolve such dramatic cave-specific traits.

Another interesting discovery happened in a nearby cave, where the team found a living population of large, pale, eyeless spiders, which is likely a new species. These slow-moving spiders build vast webs between rocks and show no aggression or defensive behavior, making them especially vulnerable. 

Also, like many other cave-dwelling spiders in the region, this species appears to exist only in this single cave. However, unfortunately, the researchers also found fox scat and a dead fox inside, raising alarms about the risk posed by invasive predators that may be preying on these fragile animals.

There are many more caves to be explored

Both the dead and living creatures found in the caves reveal how species can evolve in total darkness, cut off from the surface world for thousands of years. The adaptations seen in these organisms, such as blindness, reduced limbs, and slow movement, help scientists understand how life can persist under extreme pressures. 

However, the researchers have only checked a few caves. There are thousands more hidden in the Nullarbor region, and researchers believe many more unknown species are waiting to be found in the darkness. 

“There are thousands of caves on the Nullarbor, many of which have not had scientific surveys, and our findings indicate that there may be many more weird, wonderful, and scientifically important species out there,” Marsh said.

Marsh and her team plan to continue their explorations. However, they are concerned about the future as many of the caves lie within the area of a proposed green energy project, which could lead to the destruction of these rare, dark habitats.

Hopefully, these findings will play an important role in highlighting the ecological importance of the Nullarbor caves and strengthening the case for their long-term protection.