OK, I was looking up the names that Thurge suggested, since I am a mythology idiot!!! I was particularly interested in the story of Amphitrite, when I came across the name Scylla. I did some some research and discovered that Scylla was transformed into a hideous sea monster, who lives under a large rock (some accounts state that she eventually turned into a dangerous ragged rock outcropping) terrorizing sailors and fisherman. I thought it was fitting, and since Scylla is even in her species name, I was able to discuss her binomial nomenclature and teach a wee bit of mythology at the same time. The sixth and eighth graders were on board, but the seventh graders protested...darn trouble makers...lol. They claimed that it didn't really suit her, because she doesn't terrorize anything...not even crabs and snails. They were overruled though, so...
Scylla, it is!