Currently only three US states have nominated crustaceans as state symbols in the United States.  Louisiana has declared the Crayfish it's state crustacean, Maryland the Blue Crab, and Oregon's is the Dungeness Crab.  These crustaceans are a major part of the economy and culture in these three states which leads to them becoming state symbols.

Louisianna State Crustacean ~Crawfish (Procambarus clarkii) Maryland State Crustacean ~Blue Crab (Callinectes sapidus) Oregon State Crustacean ~Dungeness Crab (Metacarcinus magister)