Sydney funnel-web spider

Atrax robustus

The Sydney funnel-web spider is a species of venomous mygalomorph spider native to eastern Australia, usually found within a 100 km radius of Sydney. It is a member of a group of spiders known as Australian funnel-web spiders. Its bite is capable of causing serious injury or death in humans if left untreated.

The Sydney funnel-web is medium to large in size, with body length ranging from 1 to 5 cm . Both sexes are glossy and darkly colored, ranging from blue-black, to black, to brown or dark-plum colored.
Sydney Funnel Web Spider Female, body length 45 mm. Dark, glossy brown/plum/black colouration. The body position seen here in this female is not aggression but defence. When operating at such heightened levels, she has her defences fully primed and ready to go...that is indeed venom seeping from those incredible fangs. She kept this stance for a minute or so, then went about investigating quite calmly. Seen in shrub with leaf litter and rock spread. Photographed in container setting, then released to original location. Distribution is centred on Sydney, extending north to me here in Newcastle, south to the Illawarra region, and west to the Blue Mountains in New South Wales.  Arachnid,Araneae,Atrax robustus,Australia,Invertebrate,Mygalomorphae,Spider,Sydney Funnel Web,Sydney funnel-web spider,arthropod,macro,venomous

Appearance

Further information: :Spider anatomy
The Sydney funnel-web is medium to large in size, with body length ranging from 1 to 5 cm . Both sexes are glossy and darkly colored, ranging from blue-black, to black, to brown or dark-plum colored. 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. The average leg length for the spider in general is six to seven centimeters.
Sydney Funnel Web Spider One of several shots I took of this female, body length 45 mm. Dark, glossy brown/plum/black colouration. Seen in shrub with leaf litter and rock spread. Photographed in container, then released. Distribution is centred on Sydney, extending north to me here in Newcastle, south to the Illawarra region, and west to the Blue Mountains in New South Wales. Araneae,Atracidae,Atrax robAustralia,Macro,Mygalomorphae,Spider,Sydney Funnel Web,Sydney funnel-web spider,Venomous,arthropod,fauna,invertebrate

Distribution

Distribution is centred on Sydney, extending north to the Central Coast and south to the Illawarra region, and west to the Blue Mountains in New South Wales.

The spider can be found in moist microhabitats, including under logs and foliage.

Sydney funnel-web spiders are mostly terrestrial spiders, favouring habitats with moist sand and clays.

Behavior

Further information: :Spider behaviour
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 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.

Habitat

Distribution is centred on Sydney, extending north to the Central Coast and south to the Illawarra region, and west to the Blue Mountains in New South Wales.

The spider can be found in moist microhabitats, including under logs and foliage.

Sydney funnel-web spiders are mostly terrestrial spiders, favouring habitats with moist sand and clays.

Defense

Funnel-web spider venom contains a compound known as atracotoxin, an ion channel inhibitor, which makes the venom highly toxic for humans and other primates. However, it does not affect the nervous system of other mammals. These spiders typically deliver a full envenomation when they bite, often striking repeatedly, due to their defensiveness and large chitinous cheliceral fangs. There has been no reported case of severe envenoming by female funnel-web spiders, which is consistent with the finding that the venom of female specimens is less potent than the venom of their male counterparts.
In the case of severe envenomation, the time to onset of symptoms is less than one hour, with a study about funnel-web spider bites finding a median time of 28 minutes. This same study revealed that children are at a particular risk of severe funnel-web envenoming, with 42% of all cases of severe envenoming being children.
There is at least one recorded case of a small child dying within 15 minutes of a bite from a Sydney funnel-web spider.The antivenom was developed by a team headed by Struan Sutherland at the Commonwealth Serum Laboratories in Melbourne. Since the antivenom became available in 1981, there have been no recorded fatalities from Sydney funnel-web spider bites. In September 2012, it was reported that stocks of antivenom were running low, and members of the public were asked to catch the spiders so that they could be milked for their venom. One dose of antivenom requires around 70 milkings from a spider.

As part of its milking programme in January 2016, the Australian Reptile Park received a male Sydney funnel-web spider with a 10-centimetre leg span. The spider was described by the park as the largest specimen that it had seen.

References:

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Taxonomy
KingdomAnimalia
DivisionArthropoda
ClassArachnida
OrderAraneae
FamilyAtracidae
GenusAtrax
SpeciesA. robustus
Photographed in
Australia