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"Crazy Paving Cave" Closes So New Zealand's Biggest Spider Can Hang Its Baby Balls In Peace


Rachael Funnell

Digital Content Producer

clockJun 2 2022, 14:44 UTC
spelungula cavernicola nelson cave

The silken arancini is stuffed with baby spiders instead of rice. Image credit: © Bernd Dietrich, CC BY-NC 4.0, via iNaturalist

The Nelson Cave spider is New Zealand’s biggest spider and is named for a cave in which it hangs its eggs in sacs that dangle from the ceiling, each one containing around 50 spiderlings. However, according to the Department of Conservation, only one such baby ball has been seen in Nelson Cave since 2018, and rangers are concerned it could be the result of too many humans visiting their home.

The “Crazy Paving Cave,” as Nelson Cave is also known, is a tourist attraction as it has a peculiar floor pattern that is the result of mud deposits drying out over a long period of time. The resulting effect is, indeed, some pretty crazy paving, above which hangs the eggs of Spelungula cavernicola.

spelungula cavernicola nelson cave
 A wee S. cavernicola egg sac hangs above the crazy paving of Nelson Cave. Image credit: Pseudopanax at English Wikipedia, Public domain, via Wikimedia Commons

The Nelson Cave spider is joined in the darkness by beetles and w?t? – massive, flightless crickets which are some of the planet’s heaviest insects and also happen to be S. cavernicola’s favorite food. You might think a predatory spider capable of taking down the henchest invertebrates in the insect world is doing just fine, but the species’ recent reproductive failures paint a very different picture.

weta spelungula cavernicola
The Nelson Cave spider doesn't believe in "light snacks". Image credit: Dinobass, CC BY-SA 4.0, via Wikimedia Commons

“The number of spiders seen have actually increased from about 2019 onwards, possibly due to a decrease in visitor numbers associated with COVID,” said Department of Conservation senior biodiversity ranger Scott Freeman in a statement.

“However, only one egg sac has been seen since 2018.”

egg sac nelson cave spider
Just one of these babies can pack around 50 S. cavernicola spiderlings. Image credit: © Lisa Bennett, CC BY 4.0, via iNaturalist

The Crazy Paving Cave’s giant spiders are the only species within the Spelungula genus – which is too fun to say to be allowed to slip into extinction – so New Zealand is taking steps to protect the country’s biggest arachnids.


“Breeding is the real long-term driver of the population so we want to close the cave to see if this will allow breeding to improve,” Freeman explained. “Closing the cave means we can monitor the spider population's response to the removal of human visitors.”

nelson cave splungula cavernicola
Nelson Cave belongs to S. cavernicola, now. Image credit: © Melissa Hutchison, CC BY-NC-ND, via iNaturalist 

Beyond being enormous arachnids, Nelson Cave spiders are thought to represent a missing link that connects Gondwana’s primitive spiders – from which S. cavernicola emerged around 350 million years ago – to today’s modern spiders. This impressive claim has seen them become the only spider species protected by New Zealand’s 1953 Wildlife Act, and since they’ve been here a lot longer than us, it figures they should get to lay claim to at least one cave.

spelungula cavernicola nelson cave
As the only species in the Spelungula genus, S. cavernicola is pretty special. Image credit: © Ivan Magalhaes, CC BY-NC 4.0, via iNaturalist

If you, too, appreciate spiders in all their leggy, eggy wonder, sometimes the best way to help them is to leave them well alone. As such, S. cavernicola is reclaiming the Crazy Paving Cave for the next 12 months, and we wish it all the best with its baby-ball boom bonanza.

[H/T: RNZ]

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