With highly toxic venom produced in large amounts and large fangs to inject it, the Sydney funnel-web is without a doubt the deadliest spider in Australia, and possibly the world.
Found in New South Wales, in forests as well as populated urban areas, they burrow in humid sheltered places. They can wander in backyards and sometimes fall into swimming pools, and though they’re not often encountered, they can be quite aggressive when threatened.
Though just 1.5-3.5cm big, the Sydney Funnel-web has fangs larger than a brown snake’s and so powerful they can even pierce through nails and toenails. Their venom has a compound that can attack the human nervous system and alter the functioning of all organs and, when coming from a male, can kill. One in six bites causes a severe reaction, but since the antivenom has been made available, in 1981, no fatalities have been recorded.
The Sydney funnel-web is medium to large in size, with body length ranging from 1 to 5 cm (0.39 to 1.97 in). Both sexes are glossy and darkly coloured, ranging from blue-black, to black, to brown or dark-plum coloured. The carapace covering the cephalothorax is almost hairless and appears smooth and glossy. Another characteristic are finger-like spinnerets at the end of their abdomen. The shorter-lived male is smaller than the female but longer legged.
Sydney funnel-web spiders are mostly terrestrial spiders, favouring habitats with moist sand and clays. They typically build silk-lined tubular burrow retreats with collapsed “tunnels” or open “funnel” entrances from which irregular trip-lines radiate over the ground. In some exceptions, which lack trip-lines but may have trapdoors, the silk entrance tube may be split into two openings, in a Y or T form. Sydney funnel-webs burrow in sheltered habitats where they can find a moist and humid climate, for instance under rocks, logs or borer holes in rough-barked trees. The burrow may be in the hollow of a tree trunk or limb, many metres above ground level. The long-lived female funnel-webs spend most of the time in their silk-lined tubular burrow retreats. When potential prey, which includes insects, lizards or frogs, walks across the trip-lines, they rush out, subduing their prey by injecting their venom. Males, recognized by the modified terminal segment of the palp, tend to wander during the warmer months of the year, looking for receptive females to mate with. This makes encounters with male specimens more likely as they sometimes wander into backyards or houses, or fall into swimming pools. The spiders can survive such immersion for up to twenty-four hours, trapping air bubbles on hairs around their abdomen. The spiders are mainly active at night, as typical day-time conditions would dehydrate them. During the day, they seek cover in cool, moist hideaways. After heavy rain, spider activity is increased as their burrows may be flooded. When threatened or provoked, funnel-web spiders will display aggressive behaviour, rearing up on their hind legs and displaying their fangs. When biting, the funnel-web spiders maintain a tight grip on their victim, often biting repeatedly.
There are about 40 species of funnel-web spiders in Australia, but only six have been reported to cause severe envenomation, with victims generally around southern Queensland and northern New South Wales.
The impressive northern tree funnel-web spider, Hadronyche formidabilis, (4-5 cm long) and the smaller southern tree funnel-web spider, H. cerberea probably count as the most dangerous ones. Half their bites result in severe envenoming.
Every year, up to 30-40 people are bitten by funnel-web spiders. But antivenom is available and proved very effective. They feed on prey ranging from beetles to frogs and appear to be generally more active in the warmer months, between November and March.