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Into a spider’s web

This is the extraordinary story of the life and death of the world’s oldest known spider

Image Credit: AFP
The world’s oldest known spider which has died at the ripe old age of 43 after being monitored for years during a long-term population study in Perth, Australia.
Gulf News

She was born beneath an acacia tree in one of the few patches of wilderness left in the southwest Australian wheat belt, in an underground burrow lined with her mother’s perfect silk.

Her mother had used the same silk, strong and thick, to seal the burrow’s entrance against the withering heat of the summer of 1974, and against all the flying, prodding things that prowled the North Bungulla Reserve.

She lived like that, in safety and darkness, for the first six months of her life. Then one day in the rainy autumn months, her mother unsealed the tunnel and she left.

It’s likely that two or three dozen spiderlings left the burrow with her, and that nearly all of them soon died.

The 250-acre North Bungulla Reserve was surrounded completely by farmland, roads, abutting an abandoned gravel pit. Space was scarce under the leaves’ protective shade, and competition was fierce. Most of the spider’s siblings would be eaten by birds or lizards, or cannibalized by each other, or bake to death in the sun.

But she was fortunate. She found an unoccupied patch of earth a few feet from her mother’s burrow, and began to dig.

She dug an almost perfect circle straight down into the soil, just large enough to fit her body, a small fraction of an inch across. Then she lined the tunnel with silk, as her mother had lined the one she hatched in.

For as long as she lived, this would be her only home.

 

Home silken home

She wove a silken door across the burrow’s mouth, attached on one side to make a hinge. She dragged hundreds of twigs to the edge of the doorway, one by one, so that they radiated out like fan blades.

Then she went inside, closed the door and waited, likely days or even weeks, for her first real meal.

She was essentially blind, but attuned to every vibration in the earth, so when she finally felt something move along the twigs — an ant or small beetle, maybe — she leapt out and pulled it in.

In this way, she caught food when it came to her, and hid from the outside when there was nothing to eat. Scientists called her Gaius villosus — one of dozens of trapdoor spider species that lived in the vanishing wilderness of the Australian wheat belt.

 

And then in 1975...

... after a year in her burrow, she would have felt strange, heavy vibrations on the twigs outside her door. These vibrations were caused by Barbara York Main, who was standing directly over the burrow.

Main, a zoologist with the University of Western Australia, had grown up in the wheat belt. Throughout the 20th century, farming and industrialisation had destroyed almost all the wilderness in the region — leaving patches like the North Bungulla Reserve as precious sanctuaries for the tiny species that held her fascination.

On that day in 1975, she knelt over the burrow, parted the twigs behind the spider’s door and fixed a small metal sign into the soil.

It was engraved, “16.”

A few feet away, Main had marked another burrow “1,” and deduced that 1 was 16’s likely mother. And 24 and 30 were her likely sisters.

Main spent hours beneath the acacia tree, marking every burrow she could find. She was building a family tree of the species of Gaius villosus [spiders], whose hold on the earth seemed so fragile, and about which humans knew so little.

 

Long hard summers

The next years were hard for the spiders. A long, dry summer in 1977 wiped out a third of one year’s generation, Main wrote.

Still, 16 survived and grew larger, expanding her burrow every year, until it was as wide as a dime, then a quarter, and larger still.

Gaius villosus was a resilient species, Main wrote when she published her first major paper on the project, in the Bulletin of the British Arachnological Society in 1978.

Main mentioned spider 16 only in passing in this early paper. She was only 4 years old, and nothing special, yet.

But even Main did not guess how much 16 would overachieve.

Over the decades, spider 16’s mother, siblings and countless cousins and children died. But the family tree kept growing, and each time 16’s burrow hole was checked, it looked immaculate as ever.

 

On the trail of Spider 16

In 2013, an Australian Broadcasting Corp. reporter named Vicki Laurie became intrigued by reports that an 84-year-old zoologist had been cataloguing a family of spiders for 40 straight years.

So Laurie travelled with Main, out to an “an unremarkable bit of scrub” in the wheat belt, and watched her work.

When they reached the plaque of spider 16, Laurie was sceptical that it had really been occupied by the same spider for the last four decades. But Main explained that females never left their burrows until they died, and no other spider ever moved in.

Main flipped open the door with a small knife, and through Laurie, 16 was introduced to the world.

On each excursion, they would beeline directly to 16’s door, to visit the spider that never seemed to die.

 

Taking over the trail of Spider 16

Main’s plan of cataloguing a family of spiders having succeeded far beyond her expectations, and she began to look forward to the project’s end.

“She was going to finish the study when number 16 died,” Leanda Mason, who worked with Main, said. “She was going to write it up as a big thing.”

Instead, she said, Main’s health declined before the spider’s.

The zoologist retired last year, in her late 80s, and Mason, now studying for her doctorate in ecology at Curtin University, took over the spider study.

On October 31, 2017, she went out to the reserve with a drone, hoping to get a bird’s-eye view of how this small rectangle of bushland was holding up against the roads and fields.

But like her mentor before her, she went straight to 16 first.

When she arrived at the clearing that day, she noticed that the twigs around the door had lost their meticulous spiral fan shape. They lay scattered in disarray.

Mason looked at the silk door, and saw a tiny hole in the center, as if something had pierced it.

She lifted the door and lowered an endoscope into the burrow, and confirmed what she already suspected. The spider was gone.

A parasitic wasp had likely broken through the seal, and laid its eggs in 16’s body.

“She was cut down in her prime,” Mason said. “It took a while to sink in, to be honest.”

On April 19, Mason, Main and Grant Wardell-Johnson co-published a paper in Pacific Conservation Biology, announcing the death of spider 16 at age 43.

She was the oldest spider known to have existed, Mason wrote, eclipsing the previous record set by a 28-year-old tarantula.

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