Agonistic displays in the Blacktip Shark (Carcharhinus limbatus) were triggered by divers slowly ascending to the surface. Two locomotor elements, rolling and tilting, were identified. They closely resemble the behavior patterns of sharks trying to shake off Sharksuckers (Echeneis naucrates). Agonistic displays and the shaking off of sharksuckers could each derive directly from the the feeding act. Alternatively the similarity of the agonistic displays and the shaking off of sharksuckers offers the possibility as well that only one of the two is directly derived from the feeding act and the other subsequently derived from the first.