虎鯨
Young and smaller individuals may be eaten by larger sharks, such as the [[great white shark]] and the [[tiger shark]]. [[Killer whale]]s have been reported to hunt blue sharks. This shark may host several species of [[parasite]]s. For example, the blue shark is the [[definitive host]] of the [[tetraphyllidea]]n [[tapeworm]], "Pelichnibothrium speciosum" ("[[Prionacestus bipartitus]]"). It becomes infected by eating intermediate hosts, probably [[opah]] ("Lampris guttatus") and/or [[longnose lancetfish]] ("Alepisaurus ferox").