When I was eight years old and living in Florida, a black widow bit my finger. Swelled up and had this giant sack of pus hanging off it. We went to the doctors immediately, and luckily saved my finger and probably my life. Unfortunately, the venom had already destroyed all the tissue around my fingernail, though, so my fingernail rotted clean off, and accidentally got ripped off while I was in a pool at Disneyworld a week after.
True story.