A guide to New Zealand's spiders: The good, the bad and the ancient

Tuesday, 25 October 2016

Warren Christiansen sent in this photo of a spider he found under his wheely bin.

Hermie the mouse-hunting huntsman has struck fear in hearts around the globe.

It turns out huntsman spiders aren't just an Australian phenomenon.

The tunnelweb spider is New Zealand's largest, and is commonly found in Wellington.

There are little Hermies in New Zealand too.

Seeking to allay your concerns, we got spider expert Cor Vink to provide the downlow on New Zealand's spider situation.

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Vink is the curator of natural history at Canterbury Museum, and it is his job to identify and name spider species in New Zealand.

The goliath birdeater spider doesn't actually eat birds that often. The name stems from this 18th century engraving which depicts the species eating a hummingbird.

While Australia has 'over a couple of hundred' species of huntsman, he said, they don't occur naturally in New Zealand.

But some Aussie immigrants have made it across the Tasman.

The Avondale spider starred in the 1990 movie Arachnophobia, standing in for a fictional deadly spider from Brazil.

There are two species 'definitely established' in Auckland, and a third in Hillmorton, Christchurch, that hasn't been seen for a while.

'So it may no longer be here.'

The Katipo spider is deadly but very rarely spotted.

While they're bigger than your average New Zealand spider, they're not 'bitey' as a couple of their cousins can be.

'They're quite harmless, I used to have a Avondale [huntsman] spider I could handle quite happily.'

But what about all those other spiders?

OUR ANCIENT ARACHNID ISLANDS

'If you study mammals you go to the fossils to look at how they were in the past, whereas with spiders you go to New Zealand,' an American colleague of Vink's once said.

We have some 2000 different spider species in New Zealand, but only 1157 have been 'described'. Ignoring the immigrant arachnids, 97 per cent are unique to our islands.

'They're everywhere, you'd probably estimate … about a million per hectare. They're mostly in our forests.'

Our largest spider by leg-span is the 'very neat' Nelson cave spider. Found only in caves around Nelson, it preys on the cave weta.

The tunnelweb spider is the largest spider by mass.

'In Wellington it's quite common under rocks, and it's quite a decent size.'

There's over 40 species of trapdoor spiders dotted around the lower-North and South Islands.

'Their lifestyle is kind of neat,' Vink said. The young females leave their mother's burrow to dig their own hole, which they live in for their 25 year life span.

This results in tunnel web spider suburbs of 30 to 50 burrows within a couple metres of one another.

OUR MOST DANGEROUS SPIDER (MYTHS)

You might have heard this one as a kid. Apparently, the daddy-long legs spider is the most poisonous spider in the world – its teeth are just too short to harm you.

'No that's actually not factual at all,' Vink said.

Researchers found it would take the venom of 50 daddy longlegs to 'have a chance' at killing a mouse, he said.

It's also said that white tails are the most dangerous spider in the country. Another spider myth busted by Vink.

'The whole rigmarole about their bite has only popped up since the 80s, and no one's ever had much of a problem with it.'

The white tail is also an Australian immigrant. There's an North Island kind and a South Island kind, which have stuck to their respective islands since colonial times.

'The one to watch out for in New Zealand is a redback.

'The Australian redback is established in Central Otago … and that would probably have the nastiest bite.'

But they keep to themselves, he said.

THE BIRD EATING SPIDER

So, the spiders in New Zealand aren't likely to pull a Hermie the huntsman. But the largest spider in the world probably would.

The goliath birdeater spider – a South American member of the tarantula family – has a leg span 'the size of a dinner plate'.

'They'll eat whatever they can overcome, but it's unlikely that they'll tackle a bird,' Vink said.

Fortunately, no spiders of the tarantula family live in New Zealand … yet.