 The tawny nurse shark has few natural predators ; attacks on this species have been reported from bull sharks ( Carcharhinus leucas ) and great hammerheads ( Sphyrna mokarran ) , while the related nurse shark has been known to fall prey to tiger sharks ( Galeocerdo cuvier ) and lemon sharks ( Negaprion brevirostris ) . Known parasites of this species include five species of tapeworms in the genus Pedibothrium , which infest the shark 's spiral intestine . 
