Not content with merely identifying the Automeris illustris, I spent much of the evening researching to find out more about the bright green poisonous caterpillar.
The best article I discovered, by far, was this one. It's in Portuguese, but has some fabulous photos for the non-lusophone speakers out there. If you do understand Portuguese, the article references the shock-like noise we heard when trying to get the caterpillar into a jar.
Nature is truly amazing.