Most New Zealand spiders are araneomorphs. Their fangs move sideways (imagine your thumb and forefinger coming together) rather than up and down like the mygalomorphs. With this type of fang, araneomorphs do not need to have their prey on a solid surface to strike, and can exploit a far wider range of habitats than the mygalomorphs.
Spiders do not fly, but a lot of their food comes from insects that can. Araneomorphs can directly catch flying insects, and also use webs as aerial filters.
The common orb-web spider Eriophora pustulosa is seen in gardens throughout New Zealand. Often its lines are weighed down with drops of morning dew, making the web look like a diamond necklace.
At night the spider either remakes or repairs the web, and then waits for insects to fly into it once again. The spiralling lines have tiny glue droplets which stick to an insect that touches the web. Once the prey has been caught, the spider wraps it in a shroud of silk so it cannot escape. The ‘spokes’ of the web do not have glue, and are used as attachment points for the spiralling threads.
Spinning a tale
In 1981 the novelist Patricia Grace published the children’s book Te kuia me te pungawerewere or The old woman and the spider. The spider is probably the common grey house spider, Badumna longinqua. The story tells of a spinning contest between the two.
Grey house spider
The grey house spider Badumna longinqua is probably the most common spider in New Zealand, and lives in most homes and gardens. It arrived from Australia in the 19th century.
Badumna has a comb of special hairs on its back legs, to comb out the threads from its spinnerets. It builds a cobweb with a narrow tube and traps prey with a fine ‘wool’ of threads between the structural threads. Tangled prey vibrate the lines, alerting the spider.
Huntsman as stuntman
The Avondale spider (Delena cancerides) is a huntsman spider from Australia, but in New Zealand it seems to occur only in the Auckland suburb of Avondale. This is one of New Zealand’s largest spiders, up to 20 centimetres across. It was used in the 1990 film Arachnophobia instead of a tarantula because it can run across walls, while tarantulas tend to fall off.
Hunting spiders rely on stealth rather than webs. Two common species are crab spiders and jumping spiders.
Crab spiders (Thomisidae family) are common on garden plants, but are well camouflaged. They wait with outstretched arms for insects to land on the plant, then grab them. Crab spiders usually inject venom into the head of their victim and suck out its insides. They leave the body intact.
Jumping spiders (Salticidae family) have eyesight to rival a primate, and a mammal-like cunning. They will stalk a fly on the edge of a table, then walk hidden towards it, checking its position before pouncing. If the spider has to approach directly, it will crouch down and move very slowly until close enough to pounce – like a cat stalking a bird. When you look at a jumping spider closely, it will often raise its head and look back.
Many jumping spiders look like tiny primates. Some have moustache-like tufts, punk-style haircuts and jewel-coloured scales decorating their faces and bodies, to attract mates and scare off rivals. Males attract a mate by waving their legs and posturing.
The common water spider Dolomedes aquaticus has muted colouring that blends with river stones. It is not normally seen during the day, but sits and waits for prey after dark, and can survive under water for short periods.