Give this a read if you are interested in ick. I found it to be a good read about 6 months ago and just re-read it myself. Aside from the life-cycle stuff, enjoy the info about dispelling the myths about ick, specially No. 10 below (not my words!).
http://www.txinstall.com/ich/ich.htm
No. 10 The parasite burrows into the fish, below the mucous layer and into the skin. (This is why cleaner fish/shrimp can’t get to it in order to remove them from the fish). The second dumbest thing an aquarist can think: I'll get some cleaner fish or cleaner shrimp to remove/eat the parasite. THESE MARINE LIFE DO NOT EAT THE PARASITE NOR WILL FISH OR SHRIMP REMOVE THE PARASITE FROM THE INFECTED FISHES.