Size
1. Although small compared to some whales, killer whales are the largest predators of mammals ever known. Male killer whales, or bulls, average from 5.8 m to 6.7 m (19-22 ft.) and usually weigh between 3,628 kg and 5,442 kg (8,000-12,000 lb.).
2. Females, or cows, average from 4.9 m to 5.8 m (16-19 ft.) and usually weigh between 1,361 kg and 3,628 kg (3,000-8,000 lb.).
3. Individual sizes vary significantly between geographical areas. Length estimates for more than 2,000 killer whales taken by North Atlantic whaling operations show male North Atlantic killer whales average about 6.1 m (20 ft.) while females average about 5.5 m (18 ft.).
4. The largest male ever recorded was 9.8 m (32 ft.) and weighed 10,000 kg (22,000 lb.). The largest female recorded was 8.5 m (28 ft.) and weighed 7,500 kg (16,500 lb.).
Individual Behavior
1. Killer whale behavior includes spy-hopping (hanging vertically in the water with the head partially above water), breaching (jumping clear of the water and landing on the back or side), lob-tailing (slapping the tail flukes on the surface of the water), pec-slapping (slapping a pectoral flipper on the surface of the water), and dorsal fin slapping (rolling onto one side to slap the fin on the surface of the water). Scientists believe that these behaviors are connected with displays of dominance or to survey a surrounding area.
2. Killer whales may do some of these behaviors to relieve an itch, as their outer skin layer is continually sloughed as they swim. The growth of killer whale epidermal (skin) cells is about 290 times faster than that of a human forearm.
3. Killer whales in the Johnstone Strait in British Columbia often engage in beach rubbing -- they rub their bodies along the pebbly bottoms of shallow bays. The reason for this behavior is not entirely clear, but it may help the whales remove external parasites, or they may do it for the tactile stimulation.
4. Behavior studies of several cetacean species in zoological parks suggest that killer whales are among the most curious of all whales, with a great tendency to 'play' and to manipulate objects.
Food preferences and resources
1. Active and opportunistic, killer whales are without a doubt, top predators in the ocean. In fact, they are the largest predator of warm-blooded animals ever known.
2. Fishes, squids, seals, sea lions, walruses, birds, sea turtles, otters, penguins, cetaceans (both mysticete and odontocete), polar bears, reptiles, and even a moose -- they have all been found in the stomach contents of killer whales.
3. Perhaps the most interesting thing found in the stomachs of killer whales is the remains of other killer whales. How this came to be is uncertain as killer whale predation on other killer whales is rare. Perhaps they scavenged the remains of dead killer whales, as killer whales are known to eat the remains of other animals.
4. The diets of killer whales vary from one region to another.
a. In the Antarctic, killer whales eat about 67% fishes, 27% marine mammals, and 6% squids.
b. In the Bering Sea near Alaska , they eat about 65% fishes, 20% squids, and 15% marine mammals.
c. The diets of resident and transient killer whales differ as well. Resident pods eat a wide variety of fishes and rarely seek out marine mammals. Transient groups primarily eat marine mammals and occasionally eat fishes.
B. Food intake
Adult killer whales eat approximately 3% to 4% of their body weight in food per day; fully weaned calves can eat up to approximately 10% of their body weight during growth periods.
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