We get Weever fish in our waters down south, which have spines on their backs and are mildly venomous. I know as i stood on one years back, quite painful and the area swells up quite a bit, but bathed in as hot a water as you can handle draws out and eases the pain. Only lasts a few hours if you can get to hot water.
But something that can actually kill you - that woud freak me out. And that spider is fookin mental no thanks - i don't even like our house spiders which are about 1 1/2 inch lol.