Computer artwork of a female killer whale or orca (Orcinus orca). Orcas are large, predatory dolphins that are found all over the world except in the extreme poles. The females are distinguished from the males by the former's smaller size and the shape of their dorsal fins. In a male, the dorsal fin is a tall (2 m) and narrow triangle with relatively straight edges; in a female, shown here, the fin is shorter and has curved leading and trailing edges.