Also a term of abuse used by Captain Haddock by VaccaD

Question 8

WHAT TERM refers to several members of order Testudines, mostly from the Geoemydidae and Emydidae families, distinguished by mostly living in fresh or brackish water rather than in saltwater or on dry land? (It's not clear why Haddock would use this term as an insult, unless he has a grudge against a particular Big 10 school.)