killer whales are the largest living members of the dolphin family. males (called "bulls") typically range from 6 to 8 metres long and weigh in excess of 6 tonnes. females ("cows") are smaller, generally ranging from 5 to 7m and weighing about 3 to 4 t. the largest male killer whale on record was 9.8 metres, weighing over 10 tonnes, while the largest female was 8.5m, weighing 7.5 t. a baby killer whale is called a "calf". calves at birth weigh about and are about long. the killer whale's large size and strength make it among the fastest marine mammals, able to reach speeds in excess of .