Help Identify

[Little Pua]

I do not know a lot about butterflies other than I attract a lot in my large
 butterfly garden. I am doing my best to learn about each new species as I find
 them. I am trying to identify a catepiller that is eating on my native
 passionfruit vine (Passiflora Incarnata - commonly called Maypop - middle
 Tennessee). I have no plans to hurt the catapillers but would like to know
 what the are. They are about 2 inches long with a orange/reddish back, black
 feet and a lot of long black spikes that cover its entire back. Can anyone
 tell me possibilities from the limited information here? The spikes are very
 distinctive and look like they would do a very good job keeping birds and
 human hands away.

Sherry