If I am allergic to shrimp but not squid/octopus, what seafood can I eat?

I have had a few reactions to shrimp, so I have always avoided crustaceans. However, I have eaten octopus and squid with no problems. Are there other types of seafood I could be eating (oysters, scallops, etc.)? Also, I can eat regular fish (salmon, tuna, etc) and that has never been a problem for me.