Killer whales are the largest living members of the dolphin family. Males typically range from 6 to 8 metres long and weigh in excess of 6 tonnes. Females 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. 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 .