original_query: What are the characteristics of the venom of the spider species responsible for serious spider bites in Australia? 
query: What are the characteristics of the venom of the redback spider?
answer: The redback spider's venom is predominantly neurotoxic to vertebrates, causing latrodectism in humans.  It contains alpha-latrotoxin, which destabilizes cell membranes and causes excessive release of neurotransmitters, leading to pain, sweating, nausea, vomiting, headache, and agitation.