Australian spiders are mostly useful creatures, but they are often killed because of their appearance or because the person is afraid of being bitten. Although most spiders are capable of biting, they seldom do, unless in defence when they are handled or caught in clothing. The redback and Sydney funnelweb spiders have been responsible for many human deaths in the past, but no deaths have been recorded since the introduction of antivenoms in 1956, for the redback, and 1980, for the Sydney funnelweb.
Spiders are grouped in a different class from insects, called Arachnida. They have 4 pairs of legs, 2 body sections (cephalothorax and abdomen) and no antennae. Females produce a silken egg sac, after mating, which contains many eggs. The silk is produced from structures called spinnerets, which are located on the end of the abdomen. The eggs hatch inside the egg sac and the young spiderlings emerge and then immediately disperse using silken threads. The young moult several times before they reach the adult stage.
The lifecycle of most spiders is less than 12 months, but it can be many years.
GROUND DWELLING SPIDERS
These spiders live in holes in the ground, in rock crevices and in leaf litter. They emerge in search of food and often wander to find a mate during their mating season. Females tend to be slightly larger than males and have a more thickly set body and large abdomen.
SYDNEY FUNNEL WEB SPIDERS
This spider is black, with a shiny head section (cephalothorax), and long spinnerets. The female is 30mm long, the male is 25mm long and has small palps and a spur on the second front legs. Unlike most other spiders, the male is much more toxic than the female. Sydney funnelwebs favour moist, dark situations such as rockeries. They are most active during summer and autumn.
Other Funnelweb Spiders
There are many other species of funnelweb that are considered to be dangerous, for example the northern tree funnelweb and the Toowoomba funnelweb. The basic appearance of these spiders is similar but habits, size and mating seasons vary.
There are many species, but the best known is the Sydney brown trapdoor. These spiders have been known to bite if provoked and although bites can be painful, no deaths have been recorded.They are often confused with funnelweb spiders as they are a similar size, but the trapdoor spider is brown to dark brown and its spinnerets are short. The male is easily identified by its ''boxing gloves'' palps and two spines on the front legs. Trapdoor spiders tend to live in drier, more open areas than funnelweb spiders.
Mouse spiders are black and shiny and are often confused with funnelwebs. They have a large cephalothorax and the base of the fangs is also large, this is red in some males. Females are about 25mm and males 15mm in body length. Mouse spiders tend to be slow moving and not aggressive. Females live in holes in the gound and often there is a double door. Males wander in search of females, often in broad daylight. Mouse spiders can inflict a painful and toxic bite but no deaths have been recorded.
Wolf spiders are often encountered in the garden or in leaf litter. They make holes in the soil or will inhabit already existing holes. Wolf spiders are mottled grey and brown in colour and vary in body length from 15mm to 25mm. They are not an aggressive spider and move quickly when disturbed. Bites from wolf spiders may be painful and some may be toxic, but no deaths from this spider have been recorded.
ORB-WEAVING SPIDERS These spiders weave with silken threads to make an orb web to trap prey. These webs can be unpleasant to touch but are considered beautiful by many people. None of the spiders in this group are considered to be dangerous. They are not aggressive but can sometimes bite if they are handled or provoked, causing no more than a small wound. The females in this group are much larger than the males, with most males less than 5mm long.
GARDEN ORB SPIDER
A light to dark brown, hairy spider with a large abdomen. The female is about 20mm long. She hides in nearby vegetation during the day and constructs her web at night.
LEAF CURLING SPIDER
A small spider 7mm long, brown in colour, with yellow markings. It has long legs and a large abdomen and characteristically hides in a curled up leaf near the centre of the web.
ST ANDREW'S CROSS SPIDER
This spider has a brown head section and a yellow and brown striped abdomen. The female is 15mm long, with long legs and small cephalothorax. The spider derives its name from the way in which it hangs in its web, with its legs in the shape of a cross.
The redback spider is found in all states of Australia, usually making its loose web in dark and undisturbed places such as under houses, among rubbish and in seldom used outside toilets. It is related to the black widow spider of America and the katipo of New Zealand. The redback is an extremely toxic spider, known to have caused many deaths in the past. Unlike the Sydney funnelweb spider, it is not aggressive and only bites when cornered, protecting her eggs, or caught in shoes or clothing. The female redback is about 15mm long and velvety black with a red stripe on the abdomen. This stripe may be pale or missing on some spiders. The male redback is small, 3mm, unobtrusive and does not bite.
BLACK HOUSE SPIDER
The black house spider is often found around houses on windows, guttering, in the corners of sheds, and naturally in the bark cavities of trees. It is dark brown to black in colour, often with branded legs. The female is 15mm long and is larger than the male. The black house spider makes a felted web with an obvious entrance hole in the centre. The bite is toxic, producing pain, nausea and sweating but no deaths have been recorded.
These are large spiders, 15-40mm long, often appearing on the walls of houses. They live under the bark of trees but emerge at night to hunt for food. They have a buff colour, flattened and hairy body. The first 2 pairs of legs are larger than the other 2 pairs, facilitating their characteristic sideways movement.Huntsman spiders are not aggressive and seldom bite. Baits are not toxic but may be painful.
WHITE TAILED SPIDER
This spider has a dark grey to black cigar shaped body with white marks on the abdomen, particularly on the end. It is often found in bathrooms, near the tops of walls. It wanders to hunt for food. It is not an aggressive spider but will bite if handled or caught in clothing. Bites often cause burning local pain that may be followed by blistering and ulceration. There is suspicion that some bites cause tissue necrosis.No deaths have been recorded.
Other species of spiders encountered around the house and garden, which do not form a characteristic web, include the jumping spiders and net-casting spiders, all of which are harmless.