But the cartilaginous sharks form their own separate group among fish. Their many species are to be found in every ocean, but in the past, because of people's fear of sharks 'aggressive temperament and because they were not seen as an important global resource like tuna or sailfish, research into them was extremely sparse.
但屬於軟骨魚類的鯊魚在魚類中自成一門，種類繁多，每個海域都有分佈，過去人們畏於鯊魚的攻擊性，鯊魚又非鮪魚、旗魚等重要的世界性資源，研究極為缺乏。