Capt, there's growing suspicion that blue-ringed octopi, along with pufferfish and maybe even conefish, are not poisonous by themselves, that instead they're infected with some bacteria (like pseudomonas) that's gotten a gene to produce tetrodotoxin.
Potassium permanganate for treatment of poisoning? I've never heard that one... I suppose it's intended to destroy the venom (through oxidation)? Both that and the stun gun idea are simple in theory. Why don't they work?
Best guess? Australia was home to some of the last megafauna, so potent venom was a plus for making kills or preventing attacks.
There's no defensive advantage: venoms of most sorts don't work fast enough to keep the offending creature from stomping the snake to death.
There's no food-source advantage: megafauna are too big for the snakes to eat, and way too big for the funnel-web or those evil little box jellyfish. Non-poisonous snakes have no trouble finding food, so what selective advantage do Taipans have?
Australia may have poisonous marine life because it has some really cool reefs that offer much more aquatic variety than most costal areas. There are sea snakes, blue-ringed octopi, and box jellyfish in Hawaii, too.
Africa has a variety of unpleasant land animals, too. Australia doesn't have a monopoly there. Since it seems elapids evolved only in the Old World, that alone tilts the field in favor of Africa and southern Asia having lots of poisonous snakes. Europe doesn't have quite so many because it's mostly outside the tropics.
And what the Americas lack in poisonous snakes (and diamondbacks are no joke, not to mention Bushmasters if you're unlucky enough to run into one in SouthAm)... we make up for in hungry sharks, particularly in Florida!
Rich, are you teaching Miko to stay away from salt water?