OK, I have to ask this.  During the course of this thread, several people
have mentioned "sea lice".  My undergrad degree was in zoology, but I cannot
recall running across anything called "sea lice", especially anything that
stings people??  The name suggests some kind of minute arthropod, but within
the context of this thread it sounds more like some kind of jellyfish??
Just what are "sea lice"?

Paul M.