Killer whales may live for up to 35 years. At the end of a year-long pregnancy, a 3 m calf weighing 400 lbs. is born, and is nursed for one year. Males reach maturity at a length of 6 m, and females at 5 m. Males are generally larger than females, and can be up to 10 m long and weigh 8 tons. Females do not exceed 8.5 m in length.
Males have a tall, straight dorsal fin, while that of the female is smaller and hooked.
The basic social unit appears to be an extended family consisting mainly of related females, with about 20 percent males. Such groups remain together for life and travel as a cohesive unit. Vocalizations consist of a wide variety of whistles, and there is evidence that different groups are recognizable by their unique dialects. Killer whales feed on fish, squid, seabirds, and other marine mammals. They are known to hunt cooperatively, in a manner reminiscent of wolves on land.