I've had that happen to me while tarpon fishing... Big bull shark came from under the boat and ripped the Tarpon in half with 2 head shakes I was left with the head and i'd say 15% of the body. And another time had a nice snook on the line bringing it right next to the boat and all of a sudden a black tip came swimming full speed to bite off the whole tail off of the snook (had the rest of dinner that night haha)