Atrax yorkmainorum

Atrax yorkmainorum is an Australian mygalomorph funnel-web spider, belonging to the family Atracidae. According to historical records, O. Pickard-Cambridge was the first individual to document Atrax as a genus in 1877 in The Annals and Magazine of Natural History The Atrax species yorkmainorum was first described in an Australian Museum review of funnel web spiders many years later in 2010 by Michael Gray. Arachnologist, Professor Barbara York Main and her husband professor Bert Main of zoology made many contributions to the arachnology and zoology field, thus the species name yorkmainorum was named after the couple. == Description: appearance and body structure ==

The adult male of this spider species is reported to have an average body length between 16-17mm and average width of 7mm which includes the carapace (cephalothorax) and the abdomen, non-inclusive of legs. Both sexes have a deep dark brown or black appearance with a shiny body and matte abdomen. Features that distinguish Atrax yorkmainorum from Atrax robustus and Atrax sutherlandi is its slightly smaller size, absence of dorsal tibial spines on its pedipalp and the sleek, curved embolus on the male, as described by Michael, R Gray == Behaviour ==

Web Funnel web spiders including Atrax yorkmainorum are mostly nocturnal, performing their hunting and web-making at night. The web of this species is distinguishable due to the silk trip-lines that exude out from the occupied tunnel. The silk trip-lines are arranged in an irregular fashion lining the burrow, which extends roughly the length of an adult forearm. When it comes time to hunt, the spider will remain in standby in the burrow, stalking its prey until it is alerted that there is a creature walking across the white silk lines. Once alerted that there is an insect such as a beetle or cockroach, the spider advances towards the prey, injecting venom to immobilise and liquify its target to aid in digestion. For flying insects, the spider will stand on its hind legs to strike at the insect with its front legs. When threatened, Atrax species will adopt a similar stance, raising their front legs at their potential predator. == Reproduction and lifecycle ==

Male and female Atrax yorkmainorum possess reproductive organs and appendages that enable successful mating and reproduction. On the distal end of the male tibia, there is a characteristic spine on the second pair of legs which assists in the mating process. After locating a female mate through pheromone sensing, the male spider will begin the mating ritual by moving in a specific way on the female spiders' silk trap-lines to generate vibrations that the female recognises as a mating signal rather than a prey alert. After the spiderlings hatch from the females' egg sack, they will remain in the burrow until further maturity is reached. For the male Atrax species, this will occur within 3–4 years of being in the burrow, whilst for females, the final moulting process will occur 1–2 years after the male. == Distribution and habitat ==

Atrax yorkmainorum is not currently widespread across Australia. The distribution of these spiders is reported to be within forest areas of south-eastern New South Wales, as well as the Australian Capital Territory according to the Australian Museum records. The chance of encountering a funnel web spider is increased during the humid, wet months as the male is most active in these conditions as it provides a more favourable environment. Funnel web spiders are commonly found living in sheltered habitats such as under rocks or logs. == Atrax bites ==

Incidence Funnel web spiders belonging to the genre Atrax have been reported to be one of the most dangerous arachnoids around the world. The Sydney funnel web spider Atrax robustus is the most common species of Atrax involved in human death from spider bites. The release of venom from the glandular lumen of the spider occurs through contraction of the muscular layers surrounding the venom gland. The components of the spiders’ venom permit immobilisation of prey from protein substances and contains toxins that interfere with the nervous system of its victim. According to studies done on newborn mice, the lethal dose of Atrax venom for these mammals is approximately 0.16 mg/kg with a pH of 4.5-5. These toxins interfere with the normal function of sodium ion voltage-gated channels by slowing the inactivation of these channels. The resulting slow inactivation of sodium channels leads to inappropriate overstimulation of neurotransmitters such as acetylcholine, which is responsible for the paralyses effect of Atrax bites. == Atrax bite symptoms and treatment ==

Symptoms Due to the large fang size of Atrax species (~5mm), the spider bite is painful and will usually leave a mark on its victim. Following the administration of anti-venom, the patient must be monitored for >24 hours. Acute allergic reactions to anti-venom are a possibility, however the chance of this occurring is unlikely. If the bite is minor and presents no immediate symptoms of envenomation, a minimum four-hour observation period post bite is recommended. The pressure immobilisation bandage can be removed after the first two hours of observation if anti-venom is available. The development of anti-venom in the 1980s by Dr. Struan Sutherland has prevented many deaths from envenomation since it became available. If hyper secretion is still occurring in the patient, a dose of 0.6-1.2 mg of atropine can be administered to an adult, or 0.02 mg/kg to a child. == See also ==