What about the poison tree frogs in Central America? I remember hearing all the warnings about them. How poisonous are these little buggers?
For the Cone snails, frogs and the fierce snake name, again I refer y’all to:
http://www.kingsnake.com/toxinology/
They have info and links to all of those and more. It is a neat site to check out.
As for the Box Jelly debate, I read in another post (can’t remember which one, sorry) someone stating that in evolution, sometimes the first thing to work is what gets kept. Meaning it doesn’t have to evolve further, it is fine as is (even if an improvement could be made, it is uneccessary). Now in this case, quite possibly the first thing that the Jelly evolved into just happened to be the most toxic. Did it NEED to have a toxin that potent? No. But the toxin it developed just randomly happens to be that potent.
In fact, with these venomous creatures we’re talking about, why did they get that strong anyways? I mean, 218,000 LD50 mice doses per bite for the fierce snake? Is there ANY reason for venom THAT strong? Did the taipan only have venom that was 200,000 LD50 mice doses per bite strong 1,000 years ago, but something caused it to evolve a stronger venom (or to inject a tiny bit more of the same strength venom)?
I guess I’m wondering if this is a sliding scale argument (stronger and stronger over time) or a random plateau one (weak at first, then an immediate jump to a higher level).
Clearly the vector of toxin delivery matters, but these frogs sound very unpleasant.
picmr
The reason that those frogs are so nasty is that their poison is a contact poison, which doesn’t need to be injected. If you handle taipan venom with your bare hands, as long as your skin is unbroken, you’ll be fine (I think… I’m not going to try it, myself). On the other hand, if you handle a poison-arrow frog, even with intact skin, it’ll still kill you. Does this mean that the venom is potent? Not necessarily; it could just mean that it diffuses through skin easily.
I thought I was making a tasteless joke, but having read Chronos’s post, I’m not so sure any more.
picmr, you British? Some play on the word “bugger”, no doubt?
I was watching some nature show about poisonous creatures on PBS last week, and after they showed all these marine animals which had camouflage of one sort or another, there was an octopus (off the coast of Australia) which had striking neon blue patterns. I thought they said it was the most poisonous animal, and that one bite had enough venom to kill some ungodly number of people (250,000 sticks in my mind, although that’s complete speculative recall on my part). It apparently had no need to hide, because it wasn’t afraid of anything.
Anyone know anything about this? Saxifrage?
That’d be the blue-ringed octopus. What’s a little scary is that it is tiny - about 10 centimetres long. When you (hypothetically speaking) poke it with a stick its blue rings glow brightly. I couldn’t tell you how venemous it is though, but I believe it has notched up a few swimmers over the years.
BTW Irishman I’m Australian not British.
picmr
The comment on “fierce snake” in the Mailbag Answer has been (or shortly will be) amended.
picmr, sorry to cast aspersions on your heritage. 
But I’m right on the joke, correct?
Yes you were right on the joke Irishman. I was suggesting that Kvallulf had suggested that the tree frog delivered its venom per anum.
Sorry if I sound harsh, but you’re both wrong.
What you are talking about is called co-evolution. Some plants or animals once started to produce a toxic substance in the case of co-evolution a not very toxic in the beginning. Soon all animals avoid eating this plant/animal - except for one or more, which evolve ways to detoxify the toxins. And thus starts a classic arms-race, where the prey gets more and more toxic and the predator evolves better and better ways to cope with the increasing toxicity. Too bad for any other animal which try to take a bite …
If the predator does not survive, the evolutionary pressure to produce more and better toxines ceases. Therefore, if you have an extremely poisonous animal, chances are there is one - but only one - predator for a very often helpless prey (how hard is a jellyfish to kill and eat, if it weren’t toxic?).
Evolutionary advantage of the prey: Only one predator to cope with. Evolutionary advantage to the predator: No one else competes for this prey.
In a stable ecological system I would expect that, once the arms-reace has been established, the predator will evolve fast enough to keep up with increasing toxicity. Those who can’t keep up