dunno about colourful bullfrogs but the poison dart frogs are
the most poisonous things around..
then there's the rough-skinned newt with the orange belly..
it's one of the most poisonous things around, locked in an arms
race against its only natural predator, the garter snake..
the garter snake will eat the thing, lapse into a coma from the
poison and then recover.. each time, the snake increases its
resistance to the poison, the newt will up the poison toxicity...
and so on...
until now it's so poisonous, one newt has the poison to kill a few
hundred men 
