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Classification           Kingdom: Animilia           Phylum: Chordata           Subphylum: Vertebrata           Class: Mammalia           Order: Cetacea           Sub-Order: Odontoceti (toothed whales)           Family: Dlephinindae (dolphins and porpoises           Sub-family: Orcininae           Genus: Orcinus           Species: orca

 

General Characteristics                        - Females can be up to 8.5 m long, males can be up to 9.8 m long   - The largest recorded weight was 3,100 kg for females and 4,000 kg for a male   - They have a blunt head but virtually no distinguishable beak   - Killer whales pigmentation makes them easily identifiable in the water. They are usually jet black dorsally with well-demarked white or light gray ventrally.   - The flippers of females have been measured to be 11-13% of the body length.  Males' flippers have been measured 2m long.

Structure   - The skeleton is comprised of several different structures   - Cranium   - Hyoid   - Vertebral Column   - Pectoral Girdle   - Flipper   - Pelvic Girdle   - The entire skeleton is basically built on the typical delphinid plan, but is more robust in all aspects. The large jaw indicates powerful temporalis muscle for jaw closure.
Digestive System Similar to the digestive system of other delphinids. Most odontocetes have numerous peg-shaped single-rooted teeth which are generally much alike.These teeth were created for holding not for chewing.Their jaw is acutally considered weak compared to that of other mammals. Killer whales' jaws can only move in one plane. Their tongue is short and robust with a freely moveable tip. They have little or no gustatory sense, taste buds have been described in some species.
Reproduction    The genetalia of killer whales is hidden. The male's penis, when not erect, hides folded in a "S"shape in the abdomen with its tip within a prepucial slit. The female has mammary glands on either side of the genital slit,they are also hidden when she is not suckeling. It is very difficult to tell the difference between male and female killer whales. The male has a taller, straighter, and more conspicuous dorsal fin than the female.Generally there is no difference in color pattern, or overall difference in body shape, between the sexes.

Breeding cycles seem not to be fixed worldwide with matin and calving seasons often spanning several months.  In the northeast Atlantic, mating occurs from late autumn to midwinter.  Polygamy exists in killer whales, and there may be some social control of reproduction. The average size of males at sexual maturity ranges from 5.2m to 6.2m.  An adolescent growth spurt is reported in males form 5.5 to 6.1m.  Females become sexually mature between a length of 4.6 to 5.4m.

 

Courtship and Mating Courtship displays and mating in cetaceans are not always directed towards reproduction. They may simply be a way for animals to greet and bond with each other. The sense of smell is not used by cetaceans for sexual encounters. They use behavioral means to determine the sexual status of potential mates. While mating a male generally turns belly up under a willing female with its penis erect. A short intromission occures when the male has found the female's genital groove with its mobile and sensitive penis.After a killer whale becomes pregnated they remain pregnant for 19 months. After the baby whale is born it is dependent on its mothers milk for the first few months of life.

Ecology There are two forms of killer whales, the "resident" form and the "transient" form. The two live sympatric forms are believed to differ in sever aspects of morphology, ecology and behavior. The dorsal fin of the resident whales tend to be more rounded than those of the transient whales.

Resident pods are believed to have smaller home ranges than transient whales. There are also differences in the vocal paterns between the two forms. Northeastern Pacific resident killer whales are mainly piscivorous and rarely prey on marine mammals. Transient whales frequently enjoy marine mammal prey.

 

Social Organization Killer whales usually live in small groups consisting of less than 40 members usually called a pod. Many whales enjoy physical contact from eachother. They have been seen rolling and brushing against each other at or near the surface.

Life History Female killer whales have a life expetancy of 50 years. They give birth to thier first viable calf at 14 years. They produce an average of 5 calves in their life time. Males have the life expectancy of29 years.  They attain sexual maturity at 15 years.

Feeding Killer whales are marine carnivores at the end of the food chain.  Theri diets differ seasonallyand regionally. Killer whales are known to have a variety of prey, including fish, other cetaceans, pinnipeds, mustelids, birds, reptiles and cephalopods.  Most food is swallowed whole. But whenthey attack prey that is larger than them they must rip pieces to bite size pieces.  They consume 4% of their body weight every day.

Distribution Killer whales have been observed in all oceans and seas of the world. They are most abundant in colder waters of both hemispheres. The greatest abundance of killer whales is within 800 km of major continents.

 

Sightings - Alaska has an estimated 286 killer whales off its coast - British Columbia and Washington State has an estimated 260 whales - Frequent sightings have been made along the Soviet coast in the Bering Sea, Sea of Okhotsk and off the Japanese coast.

 

Threats  Killer whales are some of the largest creatures in the waters today. They are hunted for their oil and meat. Killer whales, in Japan, have the acid value of .63,the saponification value of 211.9, and the iodine value of 86.4 (Nishiwaki and Handa, 1958). They are also killed because they are potental competitors of fishermen. The fresh meat of killer whales is used for human consumption in Japan, but old meat and viscera are used as fertilizer or bait(Nishiwaki and Handa, 1958). In Norway, orcas meat is used for animal consumption  (Jonsgard and Lyshoel, 1970).

 

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