Sharks and fish swim at the Okinawa Chura Aquarium in southern Japan. Fish did not grow legs to colonize the land as previously thought, but to prop themselves up underwater 370 million years ago, according to US scientists who published a study.(AFP/JIJI PRESS/File)

词汇：

shark n.[鱼]鲨鱼

Okinawa 冲绳（群岛）

aquarium n.水族馆

colonize vt.拓殖，殖民

prop vt.支撑，维持