Canterbury Museum’s Curator of Natural History is one of the country’s leading arachnologists.
Chances are most New Zealanders have never even seen a katipō spider, and yet we’ve grown up living in fear of them. A member of the widow spider genus Latrodectus, related to the North American black widow and Australian redback, katipō have a fierce reputation for their potentially lethal bite.
Found living near the seashore amongst low-growing shrubs and rushes in sheltered, northerly facing foredunes in arid coastal areas, the katipō has survived for thousands of years in harsh environments. Sadly though, it’s at risk of joining New Zealand’s growing list of extinct native fauna, says Cor Vink, arachnologist and Canterbury Museum’s Curator of Natural History.
Female katipō are iconic (they even featured on a postage stamp) with their velvety black, pea-sized abdomen, unmistakable blood-red dorsal stripe and an hourglass-shaped marking on the underside. Adult males are only one-sixth of the female’s size and are of whiter colour.
It was long believed there were two katipō species, known as the red and black katipō, with the black katipō occupying the northern half of the North Island and the red katipō the remainder of the country (with some overlap), but recent DNA research has proved that’s not the case, says Cor. ‘DNA and morphology tells us there is no difference. The hotter it gets, the blacker they are. There is zero evidence that they are completely different species.’
Katipō live for one to two years. Females lay their eggs in an ‘egg-sac’ during summer, enclosed by a layer or two of silk. Young spiders go through up to eight moults before becoming an adult, where they shed their hard outer body walls to make room for their bodies to grow. By August or September, it’s time to mate, with the tiny males – which only moult five times – going in search of a female. Unlike some spider species where the females devour the males after the deed is done, the male katipō survives the mating, but doesn’t live much longer as he doesn’t feed as an adult. The female is then ready to lay her eggs and the cycle begins again.
Despite their diminutive size, katipō are known for their strong silk which they comb over their prey. ‘They can catch and handle insects up to seven times their size.’
Although the katipō is feared for its potentially deadly bite, Cor explains all but very few spiders are venomous, using venom to subdue their prey. However, the female katipō venom is one of the few that affects humans.
Katipō means ‘night stinger’ in Māori and although there have certainly been reported deaths since Europeans arrived in New Zealand, Cor insists our fears are largely unwarranted. ‘Bites are very uncommon. They are very shy, retiring animals, usually only biting if their webs are disturbed,’ he says. ‘The two reported deaths [in New Zealand] were both pre Treaty of Waitangi times and both occurred in children with other health complications.’ The severity of the symptoms depends on the amount of venom injected and the victim’s weight, age and general health, with the old and very young being most at risk.
That said, if you are unfortunate enough to be attacked, katipō venom packs a serious punch, delivering neurotoxins that can produce intense pain, malaise, fever, chills, trembling, restricted breathing, elevated blood pressure, and abdominal cramping. Symptoms can linger for weeks. ‘You won’t die, but you’ll certainly feel like you’re going to,’ says Cor.
But rather than living in fear, these fascinating creatures need our help. Habitat loss is likely the single greatest factor behind katipō decline because coastal development has reduced the sand dune area, where the spider lives, by around 70 per cent over the past century.
In addition, the katipō is also under threat from its invasive relative, the South African ‘false katipō’ or black cobweb spider (Steatoda capensis), first recorded in New Zealand in the 1940s. Katipō is also at risk of interbreeding with recent arachnid arrival, the Australian redback.
He says latest genetic DNA research suggests the genetic distance between the Australian redback and katipō is relatively recent, possibly within the last few hundred thousand years, with the ancestors of katipō likely to have ‘ballooned’ across the Tasman on threads of web carried by wind. Given this close genetic connection, it’s possible for the two to interbreed, but laboratory experiments have shown female redbacks tend to regard male katipō as prey, not a potential mate, whereas female katipō will happily mate with male redbacks.
A three-year survey of spiders and insects on Canterbury and Banks Peninsula beaches undertaken by Cor, in association with Simon Hodge, of Lincoln University, confirmed what experts had feared for years – numbers are in decline.
While false katipō were relatively common at sites in New Brighton Beach, they found true katipō were conspicuously absent despite earlier reports showing a clear presence of the endemic species. Over a three-year period, the pair visited New Brighton Beach 382 times searching the strand line and upper shore debris for signs of katipō, and every time they came up empty-handed.
Reports from other areas across New Zealand tell a similar tale. Previously widespread, South Island populations are now restricted to pockets from Karitane, north of Dunedin, along the east coast to Oyster Bay in Marlborough, and from Nelson up to Farewell Spit, plus a few isolated populations on the northern West Coast. In the North Island, populations have been found around Wellington, on the west coast, in the Bay of Plenty and in Northland. Canterbury’s Kaitorete Spit remains one of the last strongholds for the katipō due to its large areas of pīngao, the native sand-binding sedge, in which the katipō likes to build its web.
The Christchurch City Council is currently making a concerted effort to encourage population growth at Pegasus Bay, north of the city, by restoring the katipō’s natural habitat by planting more native plant species in the sand dunes.
In terms of New Zealand spiders though, the katipō is just the tip of the iceberg. ‘It’s just one of the ones we know about.’ While New Zealand’s larger fauna, particularly birds, have been well outlined, much of the country’s invertebrate fauna still awaits discovery or research, explains Cor. For an arachnologist, New Zealand is the place to be. He estimates there are more than 50 different families of spiders nationwide (one of which is totally unique to New Zealand), with more than 2000 different species, 97 per cent of which are only found here in New Zealand, and between 700–800 that haven’t even been named yet. To put it in perspective, he says, the United Kingdom only has 650 known species of spiders and of those, only one is unique to the British Iles.
[ WORDS Annie Studholme, IMAGES Annie Studholme ]