Killer Whale (Orcinus orca)

Killer whales occur in all oceans of the world but are more abundant in temperate and colder waters within 800 km (500 mi) of coasts. In the North Pacific, killer whales are divided into three non-associating forms or ecotypes referred to as: resident, transient, and, offshore. Resident and transient forms show distinctive differences in genetic composition, morphology, diet, ecology, distribution, movement patterns, and social structure. The offshore form is less well described, but appears to be more closely related to the resident form than to the transient form. One of the more notable differences among these forms is their diet.

All killer whales are considered top-level predators, but the diet of resident killer whales appears to be composed of fish, whereas the transient form appears to prey primarily on marine mammals. The diet of the offshore form has not been characterized but is assumed to be fish.

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