You might be interested
The vast expanse of the Nullarbor Plain, on traditional Mirning land, is an enigmatic and captivating landscape.
Once an ancient seafloor, the arid ecosystem covers over 200,000 square kilometres of desolation, traversed only by Australia’s longest, straightest highway.
Hidden beneath the monotonous desert landscape lie limestone karsts.
These formations have been hollowed out by rainfall over several millennia to create huge and little-understood cave systems.
AN UNDERLAND ADVENTURE
The Yalata Bush Blitz expedition, in 2021, was an effort to document the area’s biodiversity.
Scientists were aware that large blind, cave-dwelling spiders, known as Troglodiplura existed in the Nullarbor, but all species were only known from fragments of exoskeleton and a few juvenile spiders.
That was about to change.
Deep within the Swiss-cheese-like cave systems, arachnologist Dr Jess Marsh and speleologist Andrew Stempel became the first people on record to see a living adult Troglodiplura, this one a very large female.
Andrew was one of the caving experts hired to facilitate the underground journey.
“We entered through a little solution pipe,” says Andrew. “A few meters across, maybe five meters deep.”
From there, the intrepid explorers zigzagged deeper as they crawled through horizontal openings and rappelled down vertical sections.
“And then all I hear is people yelling from further into the cave,” says Andrew.
University of Adelaide researcher Dr Jess Marsh was one of the voices.
“They didn’t have a big enough vial to capture the thing,” says Andrew.
At one point he slid into a cramped crevice to retrieve a spider with his bare hands.
TROGLOMORPHIN’ POWER RANGERS
Jess says the experience was unforgettable.
“I will never forget seeing one for the first time,” says Jess.
“It was just like: ‘Oh, there it is’.”
“They’re beautiful animals. Completely eyeless.”
The spiders are huge – almost the size of your hand. Genetically related to trapdoor spiders, they have gigantic fangs.
Credit: Steve Milner (not for reproduction)
“We know very little about them for such a large, impressive spider.”
DARK DWELLERS
Troglomorphism is the term applied to animals that evolved to live in the complete darkness of a cave.
“They’re globally significant because they’re amongst the most troglomorphic primitive spiders in the world,” says Jess.
“They show a range of adaptations, including a complete loss of eyes and elongated limbs.” These adaptations are typical of troglomorphic creatures. So is a decrease in skin pigment, thanks to no exposure to the sun.
Caption: Troglodiplura beirutpakbarai exhibits less depigmentation than other troglomorphs.
Credit: Steve Milner (not for reproduction)
This rare species was thought to only occur in a single cave, but were discovered in three caves separated by more than 25kms.
This suggests these blind spiders may travel and spread their genes between the caves.
“It was very unexpected,” says Jess.
“I think it’s really exciting…looking at these potential subterranean dispersal mechanisms.”
“It’s like highways underground.”
Credit: Steve Milner (not for reproduction)
A MULTIFACETED THREAT
Caves generally have a consistent temperature year-round.
The Nullarbor caves are no exception, despite large variations in the above-ground temperature. This means any changes to the environment will affect the species living within.
“I think foxes are a key threat, some of the caves that we went into, there were dens and scat right through,” says Jess.
The Troglodiplura had likely been the apex predator of the Nullarbor cave systems for thousands of years.
Despite their enormous fangs, they seemed to be docile, not reacting aggressively to the presence of the scientists or cavers. This makes them easy prey for hungry foxes.
(Credit: Harley Kingston via creative commons)
THE RISK FROM ABOVE
Another potential threat to this spider species is the proposed Western Green Energy Hub.
Over the next 15 years, it aims to develop the world’s largest renewable energy hub of 25 million solar panels and 3000 wind turbines, in a development envelope of 22,690 km2.
The development of renewable energies is paramount to combat climate change and climate change itself represents a significant threat to the survival of endemic cave spiders.
Credit: Lamoix via creative commons
However, the risk of damage to the caves is high. The underground dispersal networks uncovered by the researchers present an extra challenge.
“Developers have to take into account a much broader area than just a particular cave,” says Jess.
“There are at least two caves that hold species of Troglodiplura within that development footprint, possibly more. So the potential for extinctions is high.”
