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Cow Orca And Her Calf
Photograph - Photograph
English-speaking scientists most often use the term "killer whale", although the term "orca" is increasingly used. Killer whale advocates point out it has a long heritage. Indeed, the genus name Orcinus means "of the kingdom of the dead", or "belonging to Orcus". Ancient Romans originally applied orca (plural orcae) to these animals, possibly borrowing it from the Greek ὄ���, which referred (among other things) to a whale species. Since the 1960s, orca has steadily grown in popularity; both names are now used. The term orca is preferred by some to avoid the negative connotations of "killer", and because, being part of the family Delphinidae, the species is more closely related to other dolphins than to whales.
They are sometimes referred to as blackfish, a name used for some whale species, as well. Grampus is a former name for the species, but is now seldom used. This meaning of grampus should not be confused with the Grampus genus, whose only member is Risso's dolphin.
Some examples of variations in killer whales
The three to five types of killer whales may be distinct enough to be considered different races, subspecies, or possibly even species. The IUCN reported in 2008, "The taxonomy of this genus is clearly in need of review, and it is likely that O. orca will be split into a number of different species or at least subspecies over the next few years." In the 1970s and 1980s, research off the west coast of Canada and the United States identified the following three types:
Resident: These are the most commonly sighted of the three populations in the coastal waters of the northeast Pacific. Residents' diets consist primarily of fish and sometimes squid, and they live in complex and cohesive family groups called pods. Female residents characteristically have rounded dorsal fin tips that terminate in a sharp corner. They visit the same areas consistently. British Columbia and Washington resident populations are amongst the most intensively studied marine mammals. Researchers have identified and named over 300 killer whales over the past 30 years.
Transient: The diets of these whales consist almost exclusively of marine mammals. Transients generally travel in small groups, usually of two to six animals, and have less persistent family bonds than residents. Transients vocalize in less variable and less complex dialects. Female transients are characterized by more triangular and pointed dorsal fins than those of residents. The gray or white area around the dorsal fin, known as the "saddle patch", often contains some black colouring in residents. However, the saddle patches of transients are solid and uniformly gray. Transients roam widely along the coast; some individuals have been sighted in both southern Alaska and California. Transients are also referred to as Bigg's killer whale in honor of Michael Bigg. The term has become increasingly common and may eventually replace the transient label.
Offshore: A third population of killer whales in the northeast Pacific was discovered in 1988, when a humpback whale researcher observed them in open water. As their name suggests, they travel far from shore and feed primarily on schooling fish. However, because they have large, scarred and nicked dorsal fins resembling those of mammal-hunting transients, it may be that they also eat mammals and sharks. They have mostly been encountered off the west coast of Vancouver Island and near the Queen Charlotte Islands. Offshores typically congregate in groups of 2075, with occasional sightings of larger groups of up to 200. Currently, little is known about their habits, but they are genetically distinct from residents and transients. Offshores appear to be smaller than the others, and females are characterized by dorsal fin tips that are continuously rounded.
October 22nd, 2011
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