The absence of shrimp cocktail at dinner is not a big deal to me. There are still plenty of choices available. As to the type of shrimp, this may sound a bit naiive, but I should think that the person or persons in charge of ordering food supplies (including seafood) would make every effort not to order things that could be considered unsafe for consumption. I would bet that Carnival has a list of reputable suppliers that they deal with on a regular basis. I would also bet that most people could go on a cruise, not eat ANY shrimp, and still have a great time!