although it's possible for food oysters to produce peals, they should not be confused with actual pearl oysters , which are from a different family of bivalves. true oysters , which belong to the Ostreidae family , are found throughout the world's oceans, usually in shallow waters and in colonies called beds or reefs . among the most popular and heavily harvested species are eastern american oyster , found in Atlantic waters from Canada to and the Pacific oyster , found from japan to Washington state and as far south as Australia