Killer whales are the largest member of the dolphin family. Adult males reach a length of at least 30 feet (9.1 m) and are robust in form. One specimen of 31 feet (9.5 m) was recorded for the western North Pacific. Females are considerably smaller and less stocky. Newborn are approximately 7-8 feet (2.1-2.4 m) long. Killer whales have large paddle-shaped flippers.
The most distinctive field character of the species is the dorsal fin. In adult males it is extremely erect and may be as much as 6 feet (1.8 m) tall. Though the fin of females and immature males is less than 3 feet (0.9 m) tall, it is nonetheless taller even in these animals than in any other cetacean species and is distinctly falcate and pointed on the tip.
Killer whales are basically black with an extensive region of white on the undersides extending from the lower jaw to the anal region with a branch extending onto the flanks behind the dorsal fin. There is an oval white patch on the side of the head just above and behind the eye. In newborn and very young calves, these regions may be tan to lemon yellow in color. Most animals have a light-gray saddle marking just behind the dorsal fin. The undersides of the flukes are usually white. Both all-black and all-white animals have been reported.
Natural History Notes
Killer whales travel in groups of from a few to 25 or 30 individuals, though herds of 150 have been reported. Males appear polygamous, and females and young may form groups separate from young bachelors and bulls.
Killer whales are extremely fast swimmers, capable of reaching top speeds of 25 knots or more, and have been reported "porpoising" and breaching. Individuals and entire groups have also been reported "spy-hopping," or "pitchpoling," behaviors which consist of hanging vertically in the water with the head and much of the body (to just behind the flippers) exposed above the surface.
Killer whales feed on squid, fishes, sea turtles, seabirds, and marine mammals.
Controversy still continues over whether or not killer whales pose a threat to man. Documented attacks of killer whales on boats are rare and have usually been provoked (i.e., harpooning or attempts to capture). Only two uncertain instances of attacks in the wild have been reported, but all divers and mariners should be cautioned that this powerful animal is perfectly capable of doing tremendous damage and should not be provoked.
May Be Confused With
Because of its very distinctive dorsal fin, body shape, and coloration, the killer whale is not likely to be confused with any other whale when it can be examined at close range or when an adult male is present in the group. Pods of females and immature animals, however, may be confused with false killer whales or with grampus. The killer whales may be distinguished from false killers by the following differences: