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绪论 虎鲸类型和种群

Gulf in 2008 and off Sri Lanka in 2015

Southern waters

Orca beaching to capture sea lion at Valdes Peninsula

A small population of orcas seasonally visits the northern point of the Valdes Peninsula on the east coast of Argentina and hunt for sea lions and elephant seals on the shore, temporary stranding themselves Off South Africa, a distinctive “flattooth“ morphotype exists and preys on sharks A pair of male orcas, Port and Starboard, have become well known for hunting great whites and other sharks off the South African coast

Orcas occur throughout the waters of Australia, New Zealand and Papua New Guinea They are sighted year round in New Zealand waters, while off Australia, they are seasonally concentrated off the northwest, in the inshore waters of Ningaloo Reef, and the southwest, at the Bremer region Genetic evidence shows that the orcas of New Zealand, and northwest and southwest Australia form three distinct populations New Zealand orcas mainly prey on sharks and rays

Antarctic

Around 25,000 orcas are estimated around the Antarctic, and four types have been documented Two dwarf species, named Orcinus nanus and Orcinus glacialis, were described during the 1980s by Soviet researchers, but most cetacean researchers are skeptical about their status, and linking these directly to the types described below is difficult

Some examples of variations in orcas

Type A or Antarctic orcas look like a “typical“ orca, a large, blackandwhite form with a mediumsized white eye patch, living in open water and feeding mostly on minke whales

Type B1 or pack ice orcas are smaller than type A It has a large white eye patch Most of the dark parts of its body are medium grey instead of black, although it has a dark grey patch called

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