''Orcinus'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

Delphinidae Oceanic dolphins or Delphinidae are a widely distributed family of dolphins that live in the sea. Close to forty extant species are recognised. They include several big species whose common names contain "whale" rather than "dolphin", such as the ...

, the family of carnivorous marine mammals known as dolphins. It includes the largest delphinid species, ''

Orcinus orca The orca or killer whale (''Orcinus orca'') is a toothed whale belonging to the oceanic dolphin family, of which it is the largest member. It is the only extant species in the genus ''Orcinus'' and is recognizable by its black-and-white pat ...

'', known as the orca or killer whale. Two extinct species are recognised, '' Orcinus paleorca'' and '' O. citoniensis'', describing fossilised remains of the genus. The other extinct species '' O. meyeri'' is disputed.

Taxonomy

The genus ''Orcinus'' was published by Leopold Fitzinger in 1860, its type species is the orca named by Linnaeus in 1758 as ''Delphinus orca''. Taxonomic arrangements of delphinids published by workers before and after Fitzinger, such as

John Edward Gray John Edward Gray, FRS (12 February 1800 – 7 March 1875) was a British zoologist. He was the elder brother of zoologist George Robert Gray and son of the pharmacologist and botanist Samuel Frederick Gray (1766–1828). The same is used for ...

as ''Orca'' in 1846 and ''Orca'' (''Gladiator'') in 1870, are recognised as synonyms of ''Orcinus''. The descriptions of species as ''Orcinus glacialis'' Berzin and Vladimirov, 1983 and ''Orcinus nanus'' Mikhalev and Ivashin, 1981 are considered synonyms of ''Orcinus orca'', the existing species of orca. ''Orcinus'' means "of the kingdom of the dead", or "belonging to

Orcus Orcus ( la, Orcus) was a god of the underworld, punisher of broken oaths in Etruscan and Roman mythology. As with Hades, the name of the god was also used for the underworld itself. In the later tradition, he was conflated with Dis Pater. A ...

". This comes from

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

''orca'' used by

Ancient Romans In modern historiography, ancient Rome refers to Roman civilisation from the founding of the city of Rome in the 8th century BC to the collapse of the Western Roman Empire in the 5th century AD. It encompasses the Roman Kingdom (753–509 ...

for these animals, possibly borrowing

Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic p ...

(''óryx'') which referred (among other things) to a whale species, perhaps a narwhal. As part of the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

, the species is more closely related to other oceanic dolphins than to other whales. The published names for the genus and their relationship to other delphinids combined epithets such as ''orca, grampus, gladiator'' and ''orcinus'' throughout the nineteenth century. The instability of this uncertain synonymy was complicated by the repetition of mistakes, a lack of specimens and contradictory descriptions, especially by J. E. Gray. The beaching of whales in Eastern Australia (a female and male '' Grampus griseus'') prompted a taxonomic revision in 1933, the authors

Tom Iredale Tom Iredale (24 March 1880 – 12 April 1972) was an English-born ornithologist and malacologist who had a long association with Australia, where he lived for most of his life. He was an autodidact who never went to university and lacked forma ...

and Ellis Troughton proposed that the extensive use of "''Grampus''" be conserved as the generic name of orca (''Orcinus orca'') and that a new genus named ''Grampidelphis'' be established for Rissos dolphin (''

Grampus Grampus may refer to: Animals *''Grampus'', the genus and another name for Risso's dolphin, ''Grampus griseus'' *A synonym of the genus ''Orcinus'' *Another name for ''Orcinus orca'', the killer whale or orca *Another name for the hellbender, a sp ...

''); the general stability of current species names emerged after the publication of the Philip Hershkovitz's ''Catalog of Living Whales'' (US National Museum, 1966).Hershkovitz, P. 1966. Catalog of living whales. ''Bulletin of the United States National Museum'' 246: viii 1–259 . . The type of the genus is ''Delphinus orca'', published by Linnaeus in the 10th edition of ''Systema Naturae''. The type locality was named as "''Oceano Europaeo''".

Description

A genus of carnivorous marine mammals, cetaceans of the delphinid family, with teeth in the upper and lower jaws. The possess a large brain which is informed by sophisticated auditory and echolocation techniques. The existing population, known as orca or killer whale, are a well known apex predator readily distinguished by their great size, 7 to 10 metres long, and mostly black and white coloring. These are highly intelligent and gregarious animals, able to communicate, educate, and cooperate in hunting the largest marine animals. The ecotypes within this species complex may coexist in a region, with resident and transient pods being sympatric, but these are known to be genetically isolated. Distinctions within the living ''Orcinus'' population are often observed in unique social behaviours, their cultures, which provided a significant evolutionary advantage in moving from a diet of cephlapods and fish to other mammals. The fossil remains of ''Orcinus'' species are frequently teeth, deposited during the

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Orcinus citoniensis'' is known by a well preserved skull and jaw. This specimen was an animal smaller than the orca, around 4 metres in length, and possessed a greater number of proportionally smaller teeth. The diet of modern orca is wide-ranging, although some ecotypes may be specialist fishers in a local range. Most delphinids feed on cephlapods, squid and octopuses, and earlier ''Orcinus'' species are thought to have also exploited this resource. The great size of orcas may have been the result of feeding 'up the foodchain', but the ability to prey on other mammals and the largest whales is proposed instead to be the result of exaptation. The social structure of orcas involves strategems that allow a pod to overcome animals greater in size than the individuals, whereas other great marine predators, such as ''

Carcharodon megalodon Megalodon (''Otodus megalodon''), meaning "big tooth", is an extinct species of mackerel shark that lived approximately 23 to 3.6 million years ago (Mya), from the Early Miocene to the Pliocene epochs. It was formerly thought to be a member ...

'', likely exceeded the size of their targets.

Distribution

A worldwide distribution in a wide range of habitats, deep oceans, continental shelves, arctic seas and coastal regions of every continent, including Antarctica. The modern orca is considered, after humans and their domestic animals, to be the most widely distributed mammal on the planet. ''Orcinus orca'' is able to forage at a range of coastal locations, in shallow waters, onto beaches and ice sheets, and into estuaries and rivers. They are not a common animal, but population density increases in favourable habitats of temperate and colder waters with residents and transients. Fossil evidence of ''Orcinus'' species occur in a temporal range of 3.6 million years ago until the present day. The most ancient species ''Orcinus meyeri'' refers to fossils of a partial jaw and teeth located at the early

Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

horizon of a site near

Stockach Stockach is a town in the district of Konstanz, in southern Baden-Württemberg, Germany. Location It is situated in the Hegau region, about 5 km northwest of Lake Constance, 13 km north of Radolfzell and 25 km northwest of Konstan ...

in Germany.

Classification

The classification of ''Orcinus'' within subfamilies of delphinids may be summarised as: *

** Delphininae **

Lissodelphininae Oceanic dolphins or Delphinidae are a widely distributed family of dolphins that live in the sea. Close to forty extant species are recognised. They include several big species whose common names contain "whale" rather than "dolphin", such as the ...

Globicephalinae Globicephalinae is a subfamily of oceanic dolphins that includes the pilot whales (''Globicephala'' spp.), the pygmy killer whale (''Feresa attenuata''), the rough-toothed dolphin (''Steno bredanensis''), the false killer whale (''Pseudorca cra ...

Orcininae Orcininae is a contested subfamily of oceanic dolphins composed of 1 living and 3 extinct genera. It may be superseded by Delphinidae. Its only extant member is the orca (''Orcinus orca''); all other extant genera formerly classified in it have b ...

*** ''Orcinus'' **** '' Orcinus citoniensis'' Capellini, 1883. **** '' Orcinus meyeri'' J. F. Brandt, 1873. **** ''

'' = ''Delphinus orca'' Linnaeus, 1758. The existing population, a complex predicted to include cryptic species and subspecies **** '' Orcinus paleorca'' H. Matsumoto, 1937.H. Matsumoto. 1937. A new species of orc from the basal Calabrian at Naganuma, Minato Town, Province of Kazusa, Japan. '' Zoological Magazine'' /nowiki>Dobutsugaku zasshi 49(8):191-193 citin
fossilworks
/ref> **Subfamily ''incertae sedis'' (''Lagenorhynchus albirostris'', ''Atlantic white-sided dolphin, Lagenorhynchus acutus'') The extant population is considered as a single species, although previously recognised diversity of orca populations suggests a number of cryptic species and subspecies may be recognised. Other members of Orcininae were moved to

, and the relation of ''Orcinus'' with other dolphins is unknown.

References

{{Taxonbar, from=Q2123883 Cetaceans Cetacean genera Oceanic dolphins Taxa named by Leopold Fitzinger Mammal genera with one living species