This is a factoid I heard as a kid at some point, probably on a playground somewhere, and just accepted without question in the way that children do:
All spiders are venomous, but most of them aren't venomous enough to harm humans.
(I'm pretty sure the wording used was actually "poisonous", because the distinction between venom and poison is a little too technical for a nine-year-old, but I understood it at the time to mean what I now know is called "venomous".)
Is this true? Are all spiders venomous? Or is this just one of those made-up "facts" that circulates playgrounds and campsites?