I pulled out my dictionary today to look up specifically the difference between an amphibian and a reptile. And then like always when I open my dictionary, I wind up flipping through and reading definitions. And I read something that made me feel totally vindicated!
According the the Concise Oxford American Dictionary, the plural version of octopus is OCTOPUSES! Not that dumb octopi! I've been saying that for years, you can't end a plural version of an English word with an "I."
Even an editor at Merriam Webster will tell you what the dealio is.