What spiders are dangerous and why?
All spiders can and will bite if in danger or accidentally touched.
Spiders are dangerous because they can inject venom through their fangs
when they bite. Any spider bite can cause a reaction, ranging from a
bee or wasp sting type bite to bites requiring hospitalisation.
Different people react in different ways. Bites to some people may
cause little or no reaction at all while bites to others may result in
death. It is best to be cautious around all spiders and not handle any
spider no matter how it is classified. REF20
How does spider venom work?
Venoms are complex substances made up of several components including
proteins, sugars, peptides and other substances used used for attacking
prey or defence against predators.
Venoms are made by specialised organs, the venom fluid being delivered via grooved or hollow fangs. 
Venoms affect different organisms in different ways. Some common venom
effects include paralysis, blood clotting, breakdown of muscle and
tissue, pain and effects to the cardio-respiratory system (the heart
and lungs).
Humans are effected by two types of venom, neurotoxic and cytotoxic or
necrotic venoms. Neurotoxic venoms main effect is to block nerve
impuses to the muscles, causing cramps and paralyssi of the nervous
system. The best known example is the venom of the Black Widow or
Redback spiders (Latrodectus species).
Necrotic venoms cause damage to the tissues, such as blisters and
lesions. An example is the venom of the White-tailed Spider (Lampona
cylindrata).
Generally, neurotoxic venoms kill more quickly than necrotic venoms.
VENOM LINKS
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