answer:There are several varieties of tuna, @johnny0313x. . Atlantic Bluefin Tuna (Thunnus thynnus), Southern Bluefin (Thunnus maccoyii), Albacore Tuna/Longfin Tuna (Thunnus alalunga), Yellowfin Tuna (Thunnus albacares) {Chunk Light Tuna!}, Bigeye Tuna (Thunnus obesus), Skipjack Tuna/Bonito(Katsuwonus pelamis) and Little Tunny (Euthynnus alletteratus). As for Mercury, this site claims it is a bunch of hooey.