View source for Biology:Orca

{{Short description|Largest living species of dolphin}}
{{pp-semi-indef}}
{{Use Canadian English|date=April 2020}}
{{Speciesbox
| fossil_range      = Pliocene to recent{{fossil range|Late Miocene|Recent|<ref>{{cite web|url=http://www.fossilworks.org/cgi-bin/bridge.pl?a=taxonInfo&taxon_no=64541|title=''Orcinus orca'' Linnaeus 1758|work=Fossilworks|access-date=17 December 2021}}</ref>
}}
| name              = Orca<br />Killer whale<ref name=MSW3>{{MSW3 Cetacea|id=14300074}}</ref>
| image             = Killerwhales jumping.jpg
| image_alt         = Two killer whales jump above the sea surface, showing their black, white and grey colouration. The closer whale is upright and viewed from the side, while the other whale is arching backward to display its underside.
| image_caption     = {{longitem|Transient orcas near Unimak Island, eastern [[Biography:Aleutian Islands|Aleutian Islands]], [[Earth:Alaska|Alaska]]}}
| image2            = Orca size-2.svg
| image2_alt        = Diagram showing a killer whale and scuba diver from the side: The whale is about four times longer than a [[Biology:Human|human]], who is roughly as long as the whale's dorsal fin.
| image2_caption    = {{longitem|Size compared to a {{convert|1.80|m|adj=on|}} human}}
| status            = DD
| status_system     = IUCN3.1
| status_ref        = <ref name="iucn status 19 November 2021">{{cite iucn |author=Reeves|first1= R. |author2=Pitman|first2= R. L. |author3=Ford|first3= J. K. B. |date=2017 |title=''Orcinus orca'' |volume=2017 |page=e.T15421A50368125 |doi=10.2305/IUCN.UK.2017-3.RLTS.T15421A50368125.en |access-date=19 November 2021}}</ref>
| status2           = CITES_A2
| status2_system    = CITES
| status2_ref       = <ref name = "CITES">{{Cite web|title=Appendices {{!}} CITES|url=https://cites.org/eng/app/appendices.php|access-date=2022-01-14|website=cites.org}}</ref>
| genus             = Orcinus
| species           = orca
| authority         = ([[Biography:Carl Linnaeus|Linnaeus]], [[Biology:10th edition of Systema Naturae|1758]])<ref>{{ITIS |id=180469 |taxon=''Orcinus orca'' (Linnaeus, 1758) |access-date=March 9, 2011}}</ref>
| synonyms          = *''Delphinus orca'' {{small|Linnaeus,&nbsp;1758}}
*''Delphinus gladiator'' {{small|Bonnaterre,&nbsp;1789}}
*''Orca gladiator'' {{small|(Bonnaterre,&nbsp;1789)}}
| range_map         = Orca_range.svg
| range_map_alt     = A world map shows killer whales are found throughout every ocean, except parts of the Arctic. They are also absent from the Black and Baltic seas.
| range_map_caption = {{legend2|#0577AF|''Orcinus orca'' [[Biology:Cosmopolitan distribution|range]]|outline=gray}}
}}
The '''orca''' ('''''Orcinus orca''''') or '''killer whale''' is a [[Biology:Toothed whale|toothed whale]] that is the largest member of the [[Biology:Oceanic dolphin|oceanic dolphin]] family. It is the only extant species in the genus ''[[Biology:Orcinus|Orcinus]]''. Orcas are recognizable by their black-and-white patterned body. A cosmopolitan species, orcas are found in diverse marine environments, from [[Earth:Arctic Ocean|Arctic]] to [[Earth:Southern Ocean|Antarctic regions]] to tropical seas.

Orcas are [[Biology:Apex predator|apex predator]]s with a diverse diet. Individual populations often specialize in particular types of prey. This includes a variety of [[Biology:Fish|fish]], [[Biology:Shark|shark]]s, rays, and [[Biology:Marine mammal|marine mammal]]s such as [[Biology:Pinniped|seals]] and other [[Biology:Cetacea|dolphins and whales]]. They are highly social; some populations are composed of highly stable matrilineal family groups (pods). Their sophisticated hunting techniques and vocal behaviors, often specific to a particular group and passed along from generation to generation are considered to be manifestations of [[Biology:Animal culture|animal culture]].

The [[Organization:International Union for Conservation of Nature|International Union for Conservation of Nature]] assesses the orca's [[Biology:Conservation status|conservation status]] as [[Biology:Data deficient|data deficient]] because of the likelihood that two or more orca types are [[Biology:Species problem|separate species]]. Some local populations are considered [[Biology:Threatened species|threatened]] or [[Biology:Endangered species|endangered]] due to prey depletion, habitat loss, pollution (by [[Chemistry:Polychlorinated biphenyl|PCBs]]), capture for marine mammal parks, and conflicts with human fisheries. In late 2005, the southern resident orcas, which swim in British Columbia and {{wipe|Washington (state)}} waters, were placed on the U.S. Endangered Species list.

Orcas are not usually a threat to humans, and no fatal attack has ever been documented in their natural habitat. There have been cases of captive orcas killing or injuring their handlers at marine theme parks. Orcas feature strongly in the mythologies of indigenous cultures, and their reputation in different cultures ranges from being the souls of humans to merciless killers.

==Naming==
Orcas are commonly referred to as "killer whales", despite being a type of dolphin.<ref name="whales.org">{{cite web |title=Facts about orcas (killer whales) |url=https://us.whales.org/whales-dolphins/facts-about-orcas/ |website=Whales.org |publisher=Whale & Dolphin Conservation USA |access-date=8 February 2022}}</ref> Since the 1960s, the use of "orca" instead of "killer whale" has steadily grown in common use.<ref name="price">{{cite web|first=Mary |last=Price|url=https://blog.nwf.org/2013/07/orcas-how-science-debunked-superstition/|title=Orcas: How Science Debunked Superstition|publisher=National Wildlife Federation|date=22 July 2013|access-date=30 July 2020|archive-date=January 31, 2017|archive-url=https://web.archive.org/web/20170131095114/http://blog.nwf.org/2013/07/orcas-how-science-debunked-superstition/|url-status=live}}</ref>

The genus name ''Orcinus'' means "of the kingdom of the dead",{{sfn|Ford|Ellis|Balcomb|2000|p=69}} or "belonging to [[Astronomy:Orcus|Orcus]]".<ref>[http://www.seaworld.org/animal-info/info-books/killer-whale/scientific-classification.htm Killer Whales. Scientific Classification] {{Webarchive|url=https://web.archive.org/web/20120815082034/http://www.seaworld.org/animal-info/info-books/killer-whale/scientific-classification.htm |date=August 15, 2012 }}, Seaworld.org, September 23, 2010, Retrieved September 9, 2010.</ref> [[History:Ancient Rome|Ancient Romans]] originally used ''orca''<ref>{{cite dictionary |url= https://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.04.0059%3Aentry%3Dorca1 |title= orca |last1= Lewis |first1= Charlton T. |last2= Short |first2= Charles |dictionary= A Latin Dictionary |edition= |publisher= Perseus Digital Library |date = 1879 }}</ref> (pl. ''orcae'') for these animals, possibly borrowing [[Social:Ancient Greek|Ancient Greek]] {{lang|grc|ὄρυξ}} (''óryx''). This word referred (among other things) to a whale species, perhaps a [[Biology:Narwhal|narwhal]].<ref name="Liddel">{{cite web|url=https://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.04.0057%3Aentry%3Do)%2Fruc |title=ὄρυξ |last1=Liddell |first1=Henry George|last2=Scott|first2=Robert |work=A Greek-English Lexicon |publisher=Perseus Digital Library |date= 1940 }}</ref> As part of the family [[Biology:Delphinidae|Delphinidae]], the species is more closely related to other oceanic dolphins than to other whales.<ref>{{cite book |last= Best |first= P. B. |year= 2007 |title= Whales and Dolphins of the Southern African Subregion|publisher= Cambridge University Press |isbn=978-0-521-89710-5}}</ref>

They are sometimes referred to as "blackfish", a name also used for other whale species. "Grampus" is a former name for the species, but is now seldom used. This meaning of "grampus" should not be confused with the genus ''[[Biology:Risso's dolphin|Grampus]]'', whose only member is [[Biology:Risso's dolphin|Risso's dolphin]].<ref>{{cite book |last1=Leatherwood |first1=Stephen |first2=Larry J. |last2=Hobbs |date=1988 |url=https://archive.org/details/whalesdolphinsp000leat/page/118 |title=Whales, dolphins, and porpoises of the eastern North Pacific and adjacent Arctic waters: a guide to their identification |page=118 |publisher=Courier Dover Publications |isbn=0-486-25651-0 |access-date= January 28, 2010}}</ref>

==Taxonomy==
{{multiple image |align=right |direction=vertical |width=
 |image1=Orcinus citoniensis.JPG |caption1=''[[Biology:Orcinus citoniensis|Orcinus citoniensis]]'' fossil, an extinct species of the same genus, Museo Capellini in Bologna
 |image2=Naturalis Biodiversity Center - Museum - Workshop - Lecture hall, killer whale skeleton suspended from ceiling2.jpg |caption2=Modern orca skeleton, Naturalis, Leiden
}}
''Orcinus orca'' is the only recognized extant species in the genus ''[[Biology:Orcinus|Orcinus]]'', and one of many animal species originally described by [[Biography:Carl Linnaeus|Carl Linnaeus]] in his landmark 1758 [[Biology:10th edition of Systema Naturae|10th edition of ''Systema Naturae'']].<ref>{{Cite book |last=Linnaeus |first=C. |title=Systema naturae per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I |volume=v.1 |edition=[[Biology:10th edition of Systema Naturae|10th]] |publisher=Holmiae. (Laurentii Salvii) |year=1758 |page=824 |url=https://www.biodiversitylibrary.org/item/10277#page/92/mode/1up |language=la |access-date=January 14, 2018 |archive-date=March 25, 2017 |archive-url=https://web.archive.org/web/20170325030419/http://www.biodiversitylibrary.org/item/10277#page/92/mode/1up |url-status=live }}</ref> Konrad Gessner wrote the first scientific description of an orca in his ''Piscium & aquatilium animantium natura'' of 1558, part of the larger ''Historia animalium'', based on examination of a dead stranded animal in the Bay of Greifswald that had attracted a great deal of local interest.<ref name="Greifswald church">[https://web.archive.org/web/20100120120440/http://www.marien-greifswald.de/Wal.657.0.html Zum Wal in der Marienkirche] (in German). St. Mary's Church, Greifswald. Retrieved February 16, 2010</ref>

The orca is one of 35 species in the [[Biology:Delphinidae|oceanic dolphin family]], which first appeared about 11 million years ago. The orca lineage probably branched off shortly thereafter.{{sfn|Carwardine|2001|p=19}} Although it has morphological similarities with the [[Biology:False killer whale|false killer whale]], the [[Biology:Pygmy killer whale|pygmy killer whale]] and the [[Biology:Pilot whale|pilot whale]]s, a study of cytochrome b gene sequences indicates that its closest extant relatives are the snubfin dolphins of the genus ''[[Biology:Orcaella|Orcaella]]''.<ref name=leduc>
{{cite journal |doi= 10.1111/j.1748-7692.1999.tb00833.x|last1=LeDuc |first1=R. G. |last2=Perrin |first2=W. F. |last3=Dizon |first3=A. E. |year=1999 |title= Phylogenetic relationships among the delphinid cetaceans based on full cytochrome b sequences
|journal= Marine Mammal Science |volume=15 |pages=619–648 |issue=3|bibcode=1999MMamS..15..619L }}</ref> However, a more recent (2018) study places the orca as a sister taxon to the Lissodelphininae, a [[Biology:Clade|clade]] that includes ''[[Biology:Lagenorhynchus|Lagenorhynchus]]'' and ''[[Biology:Cephalorhynchus|Cephalorhynchus]]''.<ref>{{cite journal|author=Horreo|first1= Jose L.|year=2018|title=New insights into the phylogenetic relationships among the oceanic dolphins (Cetacea: Delphinidae)|journal=Journal of Zoological Systematics and Evolutionary Research|volume=57|issue=2|pages=476–480|doi=10.1111/jzs.12255|s2cid=91933816|doi-access=free}}</ref> In contrast, a 2019 phylogenetic study found the orca to be the second most [[Biology:Basal (phylogenetics)|basal]] member of the Delphinidae, with only the [[Biology:Atlantic white-sided dolphin|Atlantic white-sided dolphin]] (''Leucopleurus acutus'') being more basal.<ref>{{Cite journal|last1=McGowen|first1=Michael R.|last2=Tsagkogeorga|first2=Georgia|last3=Álvarez-Carretero|first3=Sandra|last4=dos Reis|first4=Mario|last5=Struebig|first5=Monika|last6=Deaville|first6=Robert|last7=Jepson|first7=Paul D.|last8=Jarman|first8=Simon|last9=Polanowski|first9=Andrea|last10=Morin|first10=Phillip A.|last11=Rossiter|first11=Stephen J.|date=2019-10-21|title=Phylogenomic Resolution of the Cetacean Tree of Life Using Target Sequence Capture|url=https://doi.org/10.1093/sysbio/syz068|journal=Systematic Biology|volume=69|issue=3|pages=479–501|doi=10.1093/sysbio/syz068|issn=1063-5157|pmc=7164366|pmid=31633766}}</ref>

===Types===
{{further information|Biology:Orca types and populations}}
The three to five types of orcas may be distinct enough to be considered different races,<ref name=baird>{{harv|Baird|2002}}. [http://courses.washington.edu/mb351/readings/baird.pdf Status of Killer Whales in Canada] {{Webarchive|url=https://web.archive.org/web/20111108150031/http://courses.washington.edu/mb351/readings/baird.pdf |date=November 8, 2011 }}. Contract report to the Committee on the Status of Endangered Wildlife in Canada, Ottawa, ON, Canada. Also published as [http://www.cascadiaresearch.org/robin/kwstatus2001.pdf Status of Killer Whales, ''Orcinus orca'', in Canada] {{Webarchive|url=https://web.archive.org/web/20100714010207/http://www.cascadiaresearch.org/robin/kwstatus2001.pdf |date=July 14, 2010 }} ''The Canadian Field-Naturalist'' '''115''' (4) (2001), 676–701. Retrieved January 26, 2010.</ref> [[Biology:Subspecies|subspecies]], or possibly even [[Biology:Species|species]]<ref name="Pitman2003">{{cite journal |last1=Pitman|first1= Robert L. |last2=Ensor|first2= Paul |year=2003 |url=http://swfsc.noaa.gov/uploadedFiles/Divisions/PRD/Programs/Ecology/PitmanandEnsor2003JCRM.pdf |title=Three forms of killer whales (''Orcinus orca'') in Antarctic waters |journal=Journal of Cetacean Research and Management |volume=5 |issue=2 |pages=131–139 |doi= 10.47536/jcrm.v5i2.813 |s2cid= 52257732 |access-date=January 9, 2010 |archive-date=April 27, 2020 |archive-url=https://web.archive.org/web/20200427185038/https://swfsc.noaa.gov/uploadedFiles/Divisions/PRD/Programs/Ecology/PitmanandEnsor2003JCRM.pdf |url-status=live }}</ref> (see [[Biology:Species problem|Species problem]]). The IUCN reported in 2008, "The [[Biology:Taxonomy|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."<ref name="iucn status 19 November 2021" /> Although large variation in the ecological distinctiveness of different orca groups complicate simple differentiation into types,<ref name="de bruyn et al. 2013">{{Cite journal |last1=De Bruyn |first1=P. J. N. |last2=Tosh |first2=C. A. |last3=Terauds |first3=A. |doi=10.1111/j.1469-185X.2012.00239.x |title=Killer whale ecotypes: Is there a global model? |journal=Biological Reviews |volume=88 |issue=1 |pages=62–80 |year=2013 |pmid=22882545 |hdl=2263/21531|s2cid=6336624 |hdl-access=free }}</ref> research off the west coast of North America has identified fish-eating "residents", mammal-eating "transients" and "offshores".{{sfn|Ford|Ellis|Balcomb|2000|pp=16–21}} Other populations have not been as well studied, although specialized fish and mammal eating orcas have been distinguished elsewhere.<ref name="Jefferson et al. 1991">{{cite journal |doi=10.1111/j.1365-2907.1991.tb00291.x |last1=Jefferson |first1=T. A. |last2=Stacey |first2=P. J. |last3=Baird |first3=R. W. |year=1991 |url=http://swfsc.noaa.gov/uploadedFiles/Divisions/PRD/Publications/Jeffersonetal.1991(8).pdf |title=A review of killer whale interactions with other marine mammals: predation to co-existence |journal=Mammal Review |volume=21 |pages=151–180 |issue=4 |access-date=February 23, 2010 |archive-date=July 22, 2011 |archive-url=https://web.archive.org/web/20110722004728/http://swfsc.noaa.gov/uploadedFiles/Divisions/PRD/Publications/Jeffersonetal.1991(8).pdf |url-status=live }}</ref> Mammal-eating orcas in different regions were long thought likely to be closely related, but genetic testing has refuted this hypothesis.<ref name=Schrope>{{cite journal |title=Food chains: Killer in the kelp |journal=Nature |author=Schrope|first1= Mark |volume=445 |pages=703–705 |year=2007 |doi=10.1038/445703a |pmid=17301765 |issue=7129 |bibcode=2007Natur.445..703S |s2cid=4421362 |doi-access=free }}</ref>

Four types have been documented in the Antarctic, Types A–D. 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.<ref name="Pitman2003"/> Complete [[Biology:DNA sequencing|mitochondrial sequencing]] indicates the two Antarctic groups (types B and C) should be recognized as distinct species, as should the North Pacific transients, leaving the others as subspecies pending additional data.<ref>{{cite journal |title=Complete mitochondrial genome phylogeographic analysis of killer whales (''Orcinus orca'') indicates multiple species |first1=Phillip A. |last1= Morin |first2=Frederick |last2= Archer |first3=Andrew D. |last3= Foote |first4=Julia |last4= Vilstrup |first5=Eric E. |last5= Allen |first6=Paul |last6= Wade |first7=John |last7= Durban |first8=Kim |last8= Parsons |first9=Robert |last9= Pitman|journal=Genome Research | doi=10.1101/gr.102954.109 |pmid=20413674 |volume=20 |pages=908–916 |year=2010 |issue=7 |pmc=2892092}}</ref> A 2019 study of Type D orcas also found them to be distinct from other populations and possibly even a unique species.<ref name="Pitman et al. 2010">{{cite journal |last1=Pitman |first1=Robert L. |last2=Durban |first2=John W. |last3=Greenfelder |first3=Michael |last4=Guinet |first4=Christophe |last5=Jorgensen |first5=Morton |last6=Olson |first6=Paula A. |last7=Plana |first7=Jordi |last8=Tixier |first8=Paul |last9=Towers |first9=Jared R. |title=Observations of a distinctive morphotype of killer whale (''Orcinus orca''), type D, from subantarctic waters |journal=Polar Biology |date=August 7, 2010 |volume=34 |issue=2 |pages=303–306 |doi=10.1007/s00300-010-0871-3 |s2cid=20734772 }}</ref>

==Characteristics==
[[File:Killer whale general appearance.png|thumb|right|Different angle views of a typical female orca's appearance ]]
Orcas are the largest extant members of the dolphin family. Males typically range from {{convert|6|to|8|m}} long and weigh in excess of {{convert|6|t}}. Females are smaller, generally ranging from {{convert|5|to|7|m|abbr=on}} and weighing about {{convert|3|to|4|t}}.{{sfn|Baird|2002|p=129}} Orcas may attain larger sizes as males have been recorded at {{convert|9.8|m|abbr=on}} and females at {{convert|8.5|m|abbr=on}}.<ref name="Heyning1988"/> Large males can reach a weight of over {{convert|10|t}}.<ref>{{cite book |last1=Webber |first1=Marc A. |last2=Jefferson |first2=Thomas Allen |last3=Pitman |first3=Robert L. |title=Marine Mammals of the World: A Comprehensive Guide to Their Identification |date=28 July 2015 |publisher=Academic Press |isbn=978-0-12-409592-2 |page=189 |url=https://books.google.com/books?id=sc-cBAAAQBAJ |language=en}}</ref><ref>{{cite journal |last1=Anderson |first1=Robert |last2=Waayers |first2=Robyn |last3=Knight |first3=Andrew |title=Orca Behavior and Subsequent Aggression Associated with Oceanarium Confinement |journal=Animals |date=August 2016 |volume=6 |issue=8 |pages=49 |doi=10.3390/ani6080049 |doi-access=free |pmid=27548232 |pmc=4997274 |language=en |issn=2076-2615}}</ref> Calves at birth weigh about {{convert|180|kg|lb|abbr=on}} and are about {{convert|2.4|m|ft|abbr=on}} long.<ref>{{cite magazine|last=Olsen|first=Ken|date=2006|magazine=National Wildlife|volume=44|issue=6|pages= 22–30|title=Orcas on the edge|issn=0028-0402}}</ref><ref>{{cite magazine|last=Stewart|first=Doug|date=2001|magazine=National Wildlife|volume=39 |issue=1|pages=54–59|title=Tales of two orcas|issn=0028-0402}}</ref> The skeleton of the orca is typical for an oceanic dolphin, but more robust.<ref name="Heyning1988">{{cite journal | last1 = Heyning | first1 = J. E. | last2 = Dahlheim | first2 = M. E. | year = 1988 | title = ''Orcinus orca'' | url = http://www.science.smith.edu/msi/pdf/i0076-3519-304-01-0001.pdf | journal = Mammalian Species | issue = 304 | pages = 1–9 | doi = 10.2307/3504225 | url-status = dead | archive-url = https://web.archive.org/web/20120118134712/http://www.science.smith.edu/msi/pdf/i0076-3519-304-01-0001.pdf | archive-date = January 18, 2012 | df = mdy-all | jstor = 3504225 | s2cid = 253914153 }}</ref>

With their distinctive pigmentation,<ref name="Heyning1988"/> adult orcas are seldom confused with any other species.{{sfn|Carwardine|2001|p=20}} When seen from a distance, juveniles can be confused with [[Biology:False killer whale|false killer whale]]s or [[Biology:Risso's dolphin|Risso's dolphin]]s.<ref>{{cite web|url=http://wildwhales.org/other-species/ |title=Wild Whales|publisher=Vancouver Aquarium |access-date=March 23, 2012|url-status=dead|archive-url=https://web.archive.org/web/20120405040406/http://wildwhales.org/other-species/|archive-date=April 5, 2012}}</ref> The orca is mostly black but with sharply bordered white areas. The entire lower jaw is white and from here, the colouration stretches across the underside to the genital area; extending into lateral flank patches close to the end. The tail fluke (fin) is also white on the underside, while the eyes have white oval-shaped patches behind and above them, and a grey or white "saddle patch" exists behind the dorsal fin and across the back.<ref name="Heyning1988"/><ref name=Perrin2/> Males and females also have different patterns of black and white skin in their genital areas.{{sfn|Ford|Ellis|Balcomb|2000|p=45}} In newborns, the white areas are yellow or orange coloured.<ref name="Heyning1988"/><ref name=Perrin2>{{cite book|editor-first1=William F.|editor-last1=Perrin|editor-first2=Bernd |editor-last2= Wursig|editor-first3=J. G. M. 'Hans' |editor-last3=Thewissen|title=Encyclopedia of Marine Mammals|year=2009|publisher=Academic Press|isbn=978-0-08-091993-5|last=Ford|first=John K. B. |contribution=Killer Whale|pages=550–556}}</ref> Antarctic orcas may have pale grey to nearly white backs.{{sfn|Carwardine|2001|p=20}} Some Antarctic orcas are brown and yellow due to diatoms in the water.<ref name="Pitman2003"/> Both albino and melanistic orcas have been documented.<ref name="Heyning1988"/>

[[File:Orca wal 3.jpg|thumb|right|Differences of dorsal fins between males (front) and females (background)]]
Orca pectoral fins are large and rounded, resembling paddles, with those of males significantly larger than those of females. Dorsal fins also exhibit [[Biology:Sexual dimorphism|sexual dimorphism]], with those of males about {{convert|1.8|m|ft|abbr=on}} high, more than twice the size of the female's, with the male's fin more like an elongated [[Isosceles triangle|isosceles triangle]], whereas the female's is more curved.<ref>[https://web.archive.org/web/20110721045535/http://www.acsonline.org/factpack/KillerWhale.htm Orca (Killer whale)]. American Cetacean Society. Retrieved January 2, 2009</ref> In the skull, adult males have longer lower jaws than females, as well as larger occipital crests.{{sfn|Heptner|Nasimovich|Bannikov|Hoffmann|1996|p=681}} The snout is blunt and lacks the beak of other species.<ref name="Heyning1988"/> The orca's teeth are very strong, and its jaws exert a powerful grip; the upper teeth fall into the gaps between the lower teeth when the mouth is closed. The firm middle and back teeth hold prey in place, while the front teeth are inclined slightly forward and outward to protect them from powerful jerking movements.{{sfn|Heptner|Nasimovich|Bannikov|Hoffmann|1996|p=683}}

Orcas have good eyesight above and below the water, excellent hearing, and a good sense of touch. They have exceptionally sophisticated [[Philosophy:Animal echolocation|echolocation]] abilities, detecting the location and characteristics of prey and other objects in the water by emitting clicks and listening for echoes,{{sfn|Carwardine|2001|pp=30–32}} as do other members of the dolphin family. The mean body temperature of the orca is {{convert|36|to|38|C|F|abbr=on}}.<ref name="seaworld1">{{cite web|url=http://www.seaworld.org/animal-info/info-books/killer-whale/adaptations.htm |title=Killer Whales&nbsp;— Adaptations for an Aquatic Environment |publisher=Seaworld.org |access-date=September 14, 2013 |url-status=dead |archive-url=https://web.archive.org/web/20130904021401/http://www.seaworld.org/animal-info/info-books/killer-whale/adaptations.htm |archive-date=September 4, 2013 }}</ref><ref>N. W. Kasting, S. A. L. Adderly, T. Safford, K. G. Hewlett (1989). "Thermoregulation in Beluga (''Delphinapterus luecas'') and Killer (''Orcinus orca'') Whales"</ref> Like most marine mammals, orcas have a layer of insulating blubber ranging from {{convert|7.6|to|10|cm|in|abbr=on}} thick beneath the skin.<ref name="seaworld1"/> The pulse is about 60 heartbeats per minute when the orca is at the surface, dropping to 30 beats/min when submerged.<ref name="Spencer, Gornall & Poulter (1967)">{{cite journal |last1=Spencer |first1=M. P. |last2=Gornall 3rd |first2=T. A. |last3=Poulter |first3=T. C. |date=1967 |title=Respiratory and cardiac activity of killer whales |journal=Journal of Applied Physiology |volume=22 |issue=5 |pages=974–981 |doi=10.1152/jappl.1967.22.5.974|pmid=6025756 }}</ref>

An individual orca can often be identified from its dorsal fin and saddle patch. Variations such as nicks, scratches, and tears on the dorsal fin and the pattern of white or grey in the saddle patch are unique. Published directories contain identifying photographs and names for hundreds of North Pacific animals. Photographic identification has enabled the local population of orcas to be counted each year rather than estimated, and has enabled great insight into life cycles and social structures.{{sfn|Obee|Ellis|1992|pp=1–27}}

==Range and habitat==
{{further information|Biology:Orca types and populations}}
[[File:Orca porpoising.jpg|thumb|An orca leaps out of the water when swimming—a behaviour known as porpoising—in Hood Canal|alt=A killer whale bursts forward out of the water. Its head is just starting to point downward, and is about a body width above the surface.]]
Orcas are found in all oceans and most seas. Due to their [[Biology:Cosmopolitan distribution|enormous range]], numbers, and density, relative distribution is difficult to estimate,<ref name=Forney2007>{{Cite book |last1=Forney |first1=K. A. |last2=Wade |first2=P. |year=2007 |chapter=Worldwide distribution and abundance of killer whales |chapter-url=http://swfsc.noaa.gov/publications/FED/00851.pdf |title=Whales, whaling and ocean ecosystems |editor1-last=Estes |editor1-first=James A. |editor2-last=DeMaster |editor2-first=Douglas P. |editor3-last=Doak |editor3-first=Daniel F. |editor4-last=Williams |editor4-first=Terrie M. |editor-last5=Brownell |editor5-first=Robert L. Jr. |publisher=University of California Press |place=Berkeley |pages=145–162 |isbn=978-0-520-24884-7 |access-date=February 25, 2014 |archive-date=August 7, 2020 |archive-url=https://web.archive.org/web/20200807161432/https://swfsc.noaa.gov/publications/FED/00851.pdf |url-status=live }}</ref> but they clearly prefer higher latitudes and coastal areas over [[Earth:Pelagic zone|pelagic]] environments.{{sfn|Carwardine|2001|p=21}} Areas which serve as major study sites for the species include the coasts of Iceland, Norway, the Valdes Peninsula of Argentina, the Crozet Islands, New Zealand and parts of the west coast of North America, from {{wipe|California}} to [[Earth:Alaska|Alaska]].{{sfn|Baird|2002|p=128}} Systematic surveys indicate the highest densities of orcas (>0.40 individuals per 100&nbsp;km<sup>2</sup>) in the northeast Atlantic around the {{wipe|Norway}} coast, in the north Pacific along the [[Biography:Aleutian Islands|Aleutian Islands]], the Gulf of Alaska and in the [[Earth:Southern Ocean|Southern Ocean]] off much of the coast of [[Earth:Antarctica|Antarctica]]. They are considered "common" (0.20–0.40 individuals per 100&nbsp;km<sup>2</sup>) in the eastern Pacific along the coasts of British Columbia, {{wipe|Washington (state)}} and Oregon, in the North Atlantic Ocean around Iceland and the [[Biography:Faroe Islands|Faroe Islands]].<ref name=Forney2007/>
[[File:Killer Whale Types.jpg|thumb|right|upright|Variations in Antarctic orcas]]
In the Antarctic, orcas range up to the edge of the pack ice and are believed to venture into the denser pack ice, finding open leads much like beluga whales in the Arctic. However, orcas are merely seasonal visitors to Arctic waters, and do not approach the pack ice in the summer. With the rapid Arctic sea ice decline in the Hudson Strait, their range now extends deep into the northwest Atlantic.<ref>{{cite news|last=Kwan|first= Jennifer|url=http://uk.reuters.com/article/dcbrights-killerwhales-dc-idUKN1922990620070119|title= Canada Finds Killer Whales Drawn to Warmer Arctic|archive-url=https://web.archive.org/web/20170817162253/http://uk.reuters.com/article/dcbrights-killerwhales-dc-idUKN1922990620070119 |archive-date=August 17, 2017 |publisher= Reuters|date= January 22, 2007}}</ref> Occasionally, orcas swim into freshwater rivers. They have been documented {{convert|100|mi|km|abbr=on}} up the Columbia River in the United States.{{sfn|Baird|2002|p=10}}<ref>{{cite web |url=http://www.nwfsc.noaa.gov/research/divisions/cb/ecosystem/marinemammal/kwnewsletter/documents/email10.28.03ltrkillerwhalesnewsletter1.pdf |title=Southern Resident Killer Whale Research |orig-date=October 2003 |archive-url=https://web.archive.org/web/20140306171050/http://www.nwfsc.noaa.gov/research/divisions/cb/ecosystem/marinemammal/kwnewsletter/documents/email10.28.03ltrkillerwhalesnewsletter1.pdf |archive-date=March 6, 2014 |publisher=Northwest Fisheries Science Center |date=February 14, 2007 |access-date=January 26, 2010}}</ref> They have also been found in the Fraser River in Canada and the Horikawa River in Japan.{{sfn|Baird|2002|p=10}}

Migration patterns are poorly understood. Each summer, the same individuals appear off the coasts of British Columbia and Washington. Despite decades of research, where these animals go for the rest of the year remains unknown. Transient pods have been sighted from southern Alaska to central California.{{sfn|NMFS|2005|pp=24–29}}

===Population===
Worldwide population estimates are uncertain, but recent consensus suggests a minimum of 50,000 (2006).{{sfn|Ford|Ellis|2006}}<ref name="iucn status 19 November 2021" /><ref name=noaa>{{cite web |title=Killer whale (''Orcinus orca'') |website=NOAA Fisheries |publisher=Office of Protected Resources, National Marine Fisheries Service |url=http://www.fisheries.noaa.gov/pr/species/mammals/whales/killer-whale.html |access-date=August 15, 2017 |url-status=dead |archive-url=https://web.archive.org/web/20170709160557/http://www.fisheries.noaa.gov/pr/species/mammals/whales/killer-whale.html |archive-date=July 9, 2017 }}</ref> Local estimates include roughly 25,000 in the Antarctic, 8,500 in the tropical Pacific, 2,250–2,700 off the cooler northeast Pacific and 500–1,500 off Norway.{{sfn|NMFS|2005|p=46}} Japan's Fisheries Agency estimated in the 2000s that 2,321 orcas were in the seas around Japan.<ref>[http://sha-chi.jp/en/contents/japanorca_01e.htm Ecology of Japanese Coastal Orcas] {{webarchive|url=https://web.archive.org/web/20090822013642/http://sha-chi.jp/en/contents/japanorca_01e.htm |date=August 22, 2009 }}, sha-chi.jp. Retrieved February 17, 2010</ref><ref>[http://ika-net.jp/en/our-actions/coastal-small-cetacean-conservation/215-ten-years-after-taiji-orca-capture Ten Years after Taiji Orca Capture] {{Webarchive|url=https://web.archive.org/web/20140301122413/http://ika-net.jp/en/our-actions/coastal-small-cetacean-conservation/215-ten-years-after-taiji-orca-capture |date=March 1, 2014 }}, January 28, 2007. Iruka (dolphin) and Kujira (whale) Action Network (IKAN): Iruma, Saitama Prefecture, Japan. Retrieved February 17, 2010</ref>

==Feeding==
{{multiple image
| align = right
| direction = vertical
| width = 
| image1 = Orcinus orca (Vestfjord).jpg
| caption1 = Tail-slapping in Vestfjorden, Norway
| image2 = Killer Whale chasing Chinook.jpg
| caption2 = Resident orca pursuing a chinook
}}

Orcas are [[Biology:Apex predator|apex predator]]s, meaning that they themselves have no natural predators. They are sometimes called "wolves of the sea", because they hunt in groups like wolf packs.<ref name=marinebio>{{cite web|url=http://marinebio.org/species.asp?id=84|title=''Orcinus orca''&nbsp;– Orca (Killer Whale)|access-date=June 26, 2007|publisher=Marinebio.org|archive-date=September 16, 2011|archive-url=https://www.webcitation.org/61kbVPY6r?url=http://marinebio.org/species.asp?id=84|url-status=deviated}}</ref> Orcas hunt varied prey including fish, [[Biology:Cephalopod|cephalopod]]s, mammals, seabirds, and sea turtles.{{sfn|NMFS|2005|p=17}} Different populations or ecotypes may specialize, and some can have a dramatic impact on prey species.<ref>{{cite journal|author= Morell|first1= Virginia |title= Killer Whales Earn Their Name |journal=Science|pages= 274–276 |volume= 331 |year= 2011|doi= 10.1126/science.331.6015.274|pmid= 21252323|issue= 6015|bibcode= 2011Sci...331..274M }}</ref> However, whales in tropical areas appear to have more generalized diets due to lower food productivity.<ref name="Baird2006">{{cite journal|author=Baird|first1= R. W.|display-authors=0|year=2006|title=Killer whales in Hawaiian waters: information on population identity and feeding habits|journal=Pacific Science|volume=60|issue=4|pages=523–530|doi=10.1353/psc.2006.0024|url=http://www.cascadiaresearch.org/files/Projects/Hawaii/Baird%20et%20al%20Hawaii%20killer%20whales.pdf|hdl=10125/22585|s2cid=16788148|access-date=October 23, 2017|archive-date=October 23, 2017|archive-url=https://web.archive.org/web/20171023063253/http://www.cascadiaresearch.org/files/Projects/Hawaii/Baird%20et%20al%20Hawaii%20killer%20whales.pdf|url-status=live|hdl-access=free}}</ref><ref name="Wier">{{cite journal|author=Weir|first1= C. R.|last2=Collins|first2= T.|last3=Carvalho|first3= I.|last4=Rosenbaum|first4= H. C.|year=2010|title=Killer whales (''Orcinus orca'') in Angolan and Gulf of Guinea waters, tropical West Africa|journal=Journal of the Marine Biological Association of the United Kingdom|volume=90|issue=8|pages=1601–1611|doi=10.1017/S002531541000072X|bibcode= 2010JMBUK..90.1601W|s2cid=84721171|url=http://www.escolademar.pt/wp-content/uploads/pdf_docs/artigos/Weir_et_al_2010_final.pdf|archive-url=http://arquivo.pt/wayback/20140930081828/http://www.escolademar.pt/wp%2Dcontent/uploads/pdf_docs/artigos/Weir_et_al_2010_final.pdf|url-status=dead|archive-date=September 30, 2014}}</ref> Orcas spend most of their time at shallow depths,<ref>{{cite journal |last1=Miller |first1=Patrick James O'Malley |last2=Shapiro |first2=Ari Daniel |last3=Deecke |first3=Volker Bernt |title=The diving behaviour of mammal-eating killer whales : variations with ecological not physiological factors |journal=Canadian Journal of Zoology |date=November 2010 |volume=88 |issue=11 |pages=1103–1112 |doi=10.1139/Z10-080 |url=http://insight.cumbria.ac.uk/id/eprint/1976/1/Deecke_TheDivingBehaviour.pdf |quote=Overall, the whales spent 50% of their time 8 m or shallower and 90% of their time 40 m or shallower |access-date=August 23, 2020 |archive-date=July 20, 2018 |archive-url=https://web.archive.org/web/20180720202137/http://insight.cumbria.ac.uk/id/eprint/1976/1/Deecke_TheDivingBehaviour.pdf |url-status=live }}</ref> but occasionally dive several hundred metres depending on their prey.<ref>{{cite journal |last1=Reisinger |first1=Ryan R. |last2=Keith |first2=Mark |last3=Andrews |first3=Russel D. |last4=de Bruyn |first4=P. J. N. |title=Movement and diving of killer whales (''Orcinus orca'') at a Southern Ocean archipelago |journal=Journal of Experimental Marine Biology and Ecology |date=December 2015 |volume=473 |pages=90–102 |doi=10.1016/j.jembe.2015.08.008 |quote=maximum dive depths were 767.5 and 499.5 m|hdl=2263/49986 |url=https://figshare.com/articles/poster/Movement_and_diving_of_killer_whales_Orcinus_orca_at_a_Southern_Ocean_archipelago/3426920 |hdl-access=free }}</ref><ref>{{cite journal |last1=Towers |first1=Jared R |last2=Tixier |first2=Paul |last3=Ross |first3=Katherine A |last4=Bennett |first4=John |last5=Arnould |first5=John P Y |last6=Pitman |first6=Robert L |last7=Durban |first7=John W |last8=Northridge |first8=Simon |title=Movements and dive behaviour of a toothfish-depredating killer and sperm whale |journal=ICES Journal of Marine Science |date=January 2019 |volume=76 |issue=1 |pages=298–311 |doi=10.1093/icesjms/fsy118 |s2cid=91256980 |quote=The killer whale dove >750 m on five occasions while depredating (maximum: 1087 m), but these deep dives were always followed by long periods (3.9–4.6 h) of shallow (<100 m) diving.|doi-access=free |hdl=10536/DRO/DU:30120094 |hdl-access=free }}</ref> 

===Fish===
Fish-eating orcas prey on around 30 species of fish. Some populations in the {{wipe|Norway}} and [[Place:Greenland|Greenland]] sea specialize in [[Biology:Herring|herring]] and follow that fish's autumnal migration to the Norwegian coast. Salmon account for 96% of northeast Pacific residents' diet, including 65% of large, fatty [[Biology:Chinook salmon|Chinook]].{{sfn|NMFS|2005|p=18}} [[Biology:Chum salmon|Chum salmon]] are also eaten, but smaller [[Biology:Sockeye salmon|sockeye]] and [[Biology:Pink salmon|pink salmon]] are not a significant food item. Depletion of specific prey species in an area is, therefore, cause for concern for local populations, despite the high diversity of prey.{{sfn|Ford|Ellis|2006}} On average, an orca eats {{convert|227|kg|lb}} each day.<ref>{{cite web |url=https://kids.nationalgeographic.com/animals/mammals/facts/orca |title=National Geographic creature feature|last1=Hughes |first1=Catherine D.|date=March 2014 |access-date=July 25, 2007<!--valid url/arch confirm :11 23 June 2023 Dave-->|archive-date=June 2, 2023 |archive-url=https://web.archive.org/web/20230602193556/https://kids.nationalgeographic.com/animals/mammals/facts/orca |url-status=live }}</ref> While salmon are usually hunted by an individual whale or a small group, herring are often caught using [[Biology:Carousel feeding|carousel feeding]]: the orcas force the herring into a tight ball by releasing bursts of bubbles or flashing their white undersides. They then slap the ball with their tail flukes, stunning or killing up to 15 fish at a time, then eating them one by one. Carousel feeding has only been documented in the Norwegian orca population, as well as some oceanic dolphin species.<ref>{{Cite journal |last1=Similä|first1= T. |last2=Ugarte|first2= F. |year=1993 |title=Surface and underwater observations of cooperatively feeding killer whales in Northern Norway |journal=Canadian Journal of Zoology |volume=71 |pages=1494–1499 |doi=10.1139/z93-210 |issue=8}}</ref> 

In New Zealand, [[Biology:Shark|shark]]s and [[Biology:Batoidea|rays]] appear to be important prey, including [[Biology:New Zealand eagle ray|eagle ray]]s, [[Biology:Thorntail stingray|long-tail]] and [[Biology:Short-tail stingray|short-tail stingray]]s, [[Biology:Common thresher|common thresher]]s, [[Biology:Smooth hammerhead|smooth hammerhead]]s, [[Biology:Blue shark|blue shark]]s, basking sharks, and shortfin makos.<ref name=orcashark>{{cite journal|author=Visser|first1= Ingrid N.|year=2005|title=First Observations of Feeding on Thresher (''Alopias vulpinus'') and Hammerhead (''Sphyrna zygaena'') Sharks by Killer Whales (''Orcinus orca'') Specialising on Elasmobranch Prey|journal=Aquatic Mammals|volume=31|issue=1|pages=83–88|doi=10.1578/AM.31.1.2005.83}}</ref><ref>{{cite journal |last1=Visser|first1= Ingrid N. |first2=Jo|last2= Berghan |last3= van Meurs|first3= Rinie|first4=Dagmar |last4=Fertl |year=2000 |title=Killer Whale (''Orcinus orca'') Predation on a Shortfin Mako Shark (''Isurus oxyrinchus'') in New Zealand Waters |journal=Aquatic Mammals |volume=26 |issue=3 |pages=229–231 |url=http://aquaticmammalsjournal.org/share/AquaticMammalsIssueArchives/2000/AquaticMammals_26-03/26-03_Berghan.pdf |access-date=May 3, 2014 |archive-date=January 26, 2012 |archive-url= https://web.archive.org/web/20120126035026/http://aquaticmammalsjournal.org/share/AquaticMammalsIssueArchives/2000/AquaticMammals_26-03/26-03_Berghan.pdf |url-status=live }}</ref> With sharks, orcas may herd them to the surface and strike them with their tail flukes,<ref name=orcashark/> while bottom-dwelling rays are cornered, pinned to the ground and taken to the surface.<ref>{{cite journal|author=Visser|first1= Ingrid N.|year=1999|title=Benthic foraging on stingrays by killer whales (''Orcinus orca'') in New Zealand waters|journal=Marine Mammal Science|volume=15|issue=1|pages=220–227 |doi=10.1111/j.1748-7692.1999.tb00793.x|bibcode= 1999MMamS..15..220V}}</ref> In other parts of the world, orcas have preyed on [[Biology:Broadnose sevengill shark|broadnose sevengill shark]]s,<ref name=Engelbrecht/> small [[Biology:Whale shark|whale shark]]s<ref>{{cite web |last1=O'Sullivan |first1=J. B. |title=A fatal attack on a whale shark ''Rhincodon typus'', by killer whales ''Orcinus orca'' off Bahia de Los Angeles, Baja California |year=2000 |url=http://www.flmnh.ufl.edu/fish/meetings/abst2000c.htm |work=American Elasmobranch Society 16th Annual Meeting, June 14–20, 2000 |location=La Paz, B.C.S., México |access-date=February 18, 2010 |archive-date=February 28, 2010 |archive-url=https://web.archive.org/web/20100228204745/http://www.flmnh.ufl.edu/fish/meetings/abst2000c.htm |url-status=dead }}</ref> and even [[Biology:Great white shark|great white shark]]s.<ref name=Engelbrecht>{{cite journal|last1=Engelbrecht|first1=T. M.|last2=Kock|first2= A. A.|last3=O'Riain|first3= M. J.|year=2019|title=Running scared: when predators become prey|journal=Ecosphere |volume=10|issue=1|page=e02531 |doi=10.1002/ecs2.2531|doi-access=free|bibcode=2019Ecosp..10E2531E }}</ref><ref name=Pyle>{{cite journal |last1=Pyle |first1=Peter |last2=Schramm|first2= Mary Jane |last3=Keiper|first3= Carol |last4=Anderson|first4= Scot D. |title=Predation on a white shark (''Carcharodon carcharias'') by a killer whale (''Orcinus orca'') and a possible case of competitive displacement |journal=Marine Mammal Science |year=1999 |url=http://www.prbo.org/cms/docs/marine/MMS.pdf |volume=15 |issue=2 |pages=563–568 |doi=10.1111/j.1748-7692.1999.tb00822.x |bibcode=1999MMamS..15..563P |access-date=April 28, 2014 |archive-date=March 22, 2012 |archive-url=https://web.archive.org/web/20120322070431/http://www.prbo.org/cms/docs/marine/MMS.pdf |url-status=dead }}</ref> Competition between orcas and white sharks is probable in regions where their diets overlap.<ref>{{cite journal |last=Heithaus |first=Michael |title=Predator–prey and competitive interactions between sharks (order Selachii) and dolphins (suborder Odontoceti): a review |journal=Journal of Zoology |volume=253 |issue=1 |pages=53–68 |year=2001 |url=http://www.science.fau.edu/sharklab/courses/elasmobiology/readings/heithaus.pdf |doi=10.1017/S0952836901000061 |citeseerx=10.1.1.404.130 |access-date=January 18, 2010 |archive-url=https://web.archive.org/web/20160115113304/http://www.science.fau.edu/sharklab/courses/elasmobiology/readings/heithaus.pdf |archive-date=January 15, 2016 |url-status=dead }}</ref> The arrival of orcas in an area can cause white sharks to flee and forage elsewhere.<ref>{{cite journal|author=Jorgensen|first1= S. J.|display-authors=0|year=2019 |title=Killer whales redistribute white shark foraging pressure on seals|journal=Scientific Reports|volume=9|issue=1|page=6153 |doi=10.1038/s41598-019-39356-2 |pmid=30992478|pmc=6467992|bibcode=2019NatSR...9.6153J}}</ref><ref>{{Cite journal |last1=Towner |first1=AV |last2=Watson |first2=RGA |last3=Kock |first3=AA |last4=Papastamatiou |first4=Y |last5=Sturup |first5=M |last6=Gennari |first6=E |last7=Baker |first7=K |last8=Booth |first8=T |last9=Dicken |first9=M |last10=Chivell |first10=W |last11=Elwen |first11=S |date=2022-04-03 |title=Fear at the top: killer whale predation drives white shark absence at South Africa's largest aggregation site |url=https://doi.org/10.2989/1814232X.2022.2066723 |journal=African Journal of Marine Science |volume=44 |issue=2 |pages=139–152 |doi=10.2989/1814232X.2022.2066723 |bibcode=2022AfJMS..44..139T |s2cid=250118179 |issn=1814-232X}}</ref> Orcas appear to target the liver of sharks.<ref name=Engelbrecht/><ref name=Pyle/>

===Mammals and birds===
Orcas are sophisticated and effective predators of [[Biology:Marine mammal|marine mammal]]s. They are recorded to prey on other cetacean species, usually smaller dolphins and [[Biology:Porpoise|porpoise]]s such as [[Biology:Common dolphin|common dolphin]]s, [[Biology:Bottlenose dolphin|bottlenose dolphin]]s, [[Biology:Pacific white-sided dolphin|Pacific white-sided dolphin]]s, [[Biology:Dusky dolphin|dusky dolphin]]s, harbour porpoises and Dall's porpoises.<ref name=Perrin/><ref name=Perrin2/> While hunting these species, orcas usually have to chase them to exhaustion. For highly social species, orca pods try to separate an individual from its group. Larger groups have a better chance of preventing their prey from escaping, which is killed by being thrown around, rammed and jumped on. Arctic orcas may attack [[Biology:Beluga whale|beluga whale]]s and [[Biology:Narwhal|narwhal]]s stuck in pools enclosed by sea ice, the former are also driven into shallower water where juveniles are grabbed.<ref name=Perrin/> By contrast, orcas appear to be wary of [[Biology:Pilot whale|pilot whale]]s, which have been recorded to [[Biology:Mobbing (animal behavior)|mob]] and chase them.<ref>{{cite journal|author=Selbmann, A.|display-authors=0|year=2022|title=Occurrence of long-finned pilot whales (''Globicephala melas'') and killer whales (''Orcinus orca'') in Icelandic coastal waters and their interspecific interactions|journal=Acta Ethol|volume=25 |issue=3 |pages=141–154 |doi=10.1007/s10211-022-00394-1|pmid=35694552 |pmc=9170559 |s2cid=249487897 }}</ref> Although resident orcas have never been observed to eat other marine mammals, they occasionally harass and kill porpoises and seals for no apparent reason.{{sfn|Ford|Ellis|Balcomb|2000|p=19}} Some dolphins recognize resident orcas as harmless and remain in the same area.<ref>{{cite web |last1=Chung |first1=Emily |title=Killer whales eat dolphins. So why are these dolphins tempting fate? |url=https://www.cbc.ca/news/science/pacific-white-sided-dolphins-southern-resident-killer-whales-1.5021585 |publisher=CBC News |date=2019-02-18}}</ref>

[[File:KW attack STBW.jpg|thumb|upright=1.36|Orca attacking a strap-toothed beaked whale]]
Orcas also prey on larger species such as [[Biology:Sperm whale|sperm whale]]s, grey whales, [[Biology:Humpback whale|humpback whale]]s and minke whales.<ref name=Perrin/><ref name=Perrin2/> In 2019, orcas were recorded to have killed a [[Biology:Blue whale|blue whale]] on three separate occasions off the south coast of Western Australia, including an estimated {{convert|18|–|22|m|sp=us|adj=on}} individual.<ref>{{cite journal|author1=Totterdell, J. A.|author2=Wellard, R.|author3=Reeves, I. M.|author4=Elsdon, B.|author5=Markovic, P.|author6=Yoshida, M.|author7=Fairchild, A.|author8=Sharp, G.|author9=Pitman, R.|year=2022|title=The first three records of killer whales (''Orcinus orca'') killing and eating blue whales (''Balaenoptera musculus'')|journal=Marine Mammal Science|volume=38 |issue=3 |pages=1286–1301 |doi=10.1111/mms.12906|bibcode=2022MMamS..38.1286T | s2cid=246167673 }}</ref> Large whales require much effort and coordination to kill and orcas often target calves. A hunt begins with a chase followed by a violent attack on the exhausted prey. Large whales often show signs of orca attack via tooth rake marks.<ref name=Perrin/> Pods of female sperm whales sometimes protect themselves by forming a protective circle around their calves with their flukes facing outwards, using them to repel the attackers.<ref>{{cite journal|doi=10.1111/j.1748-7692.2001.tb01000.x|author=Pitman|first1= Robert L.|url=http://digitalcommons.unl.edu/usdeptcommercepub/507/|title=Killer Whale Predation on Sperm Whales: Observations and Implications|journal=Marine Mammal Science|volume=17|issue=3|pages=494–507|year=2001|bibcode=2001MMamS..17..494P |display-authors=0|access-date=February 25, 2014|archive-date=December 11, 2015|archive-url=https://web.archive.org/web/20151211133004/http://digitalcommons.unl.edu/usdeptcommercepub/507/|url-status=live}}</ref> There is also evidence that humpback whales will defend against or mob orcas who are attacking either humpback calves or juveniles as well as members of other species.<ref name=mobbing>{{cite journal|title=Humpback whales interfering when mammal-eating killer whales attack other species: Mobbing behavior and interspecific altruism?|journal=Marine Mammal Science | doi=10.1111/mms.12343|volume=33|pages=7–58|year=2016 | last1 = Pitman | first1 = Robert L.|doi-access=free}}</ref>

Prior to the advent of industrial whaling, great whales may have been the major food source for orcas. The introduction of modern whaling techniques may have aided orcas by the sound of [[Engineering:Harpoon cannon|exploding harpoons]] indicating the availability of prey to scavenge, and compressed air inflation of whale carcasses causing them to float, thus exposing them to scavenging. However, the devastation of great whale populations by unfettered whaling has possibly reduced their availability for orcas, and caused them to expand their consumption of smaller marine mammals, thus contributing to the decline of these as well.<ref name="EMM2009">{{cite book|last=Estes|first=James|editor=Perrin, William F.|others=Wursig, Bernd & Thewissen, J. G. M.|title=Encyclopedia of Marine Mammals|chapter-url=https://books.google.com/books?id=2rkHQpToi9sC&pg=PA360|date=February 26, 2009|publisher=Academic Press|isbn=978-0-08-091993-5|pages=357–361|chapter=Ecological effects of marine mammals|access-date=December 30, 2015|archive-date=May 9, 2016|archive-url=https://web.archive.org/web/20160509133131/https://books.google.com/books?id=2rkHQpToi9sC&pg=PA360|url-status=live}}</ref>

{{multiple image
| align = right
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| image1=Orcas in Punta Norte Valdes Peninsula - panoramio.jpg|
| caption1= Orca beaching to capture sea lion along Valdes Peninsula
| image2=Killer Whales Hunting a Crabeater Seal.jpg
| caption2=Orcas swimming in close synchronization to create a wave to wash the [[Biology:Crabeater seal|crabeater seal]] off the floe
}}
Other marine mammal prey includes [[Biology:Pinniped|seal]] species such as harbour seals, [[Biology:Elephant seal|elephant seal]]s, [[Biology:California sea lion|California sea lion]]s, [[Biology:Steller sea lion|Steller sea lion]]s, [[Biology:South American sea lion|South American sea lion]]s and [[Biology:Walrus|walrus]]es.<ref name=Perrin>{{cite book|editor-first1=William F.|editor-last1=Perrin|editor-first2=Bernd |editor-last2= Wursig|editor-first3=J. G. M. 'Hans' |editor-last3=Thewissen|title=Encyclopedia of Marine Mammals|year=2009|publisher=Academic Press|isbn=978-0-08-091993-5|last=Weller|first=D. W. |contribution=Predation on marine mammals|pages=927–930}}</ref><ref name=Perrin2/> Often, to avoid injury, orcas disable their prey before killing and eating it. This may involve throwing it in the air, slapping it with their tails, ramming it, or breaching and landing on it.{{sfn|Heimlich|Boran|2001|p=45}} In steeply banked beaches off Península Valdés, Argentina, and the Crozet Islands, orcas feed on South American sea lions and [[Biology:Southern elephant seal|southern elephant seal]]s in shallow water, even beaching temporarily to grab prey before wriggling back to the sea. Beaching, usually fatal to cetaceans, is not an instinctive behaviour, and can require years of practice for the young.{{sfn|Carwardine|2001|p=29}} Orcas can then release the animal near juvenile whales, allowing the younger whales to practice the difficult capture technique on the now-weakened prey.{{sfn|Heimlich|Boran|2001|p=45}}{{sfn|Baird|2002|pp=61–62}} In the Antarctic, type B orcas hunt [[Biology:Weddell seal|Weddell seal]]s and other prey by "wave-hunting". They "spy-hop" to locate them on resting on ice floes, and then swim in groups to create waves that wash over the floe. This washes the prey into the water, where other orcas lie in wait.<ref>{{cite journal|last1=Pitman|first1=R. L.|last2=Durban|first2=J. W.|year=2011|title=Cooperative hunting behavior, prey selectivity and prey handling by pack ice killer whales (''Orcinus orca''), type B, in Antarctic Peninsula waters|journal=Marine Mammal Science|volume=28|issue=1|pages=16–36|doi=10.1111/j.1748-7692.2010.00453.x|url=http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1305&context=usdeptcommercepub }}</ref><ref>{{cite journal|last1=Visser |first1=Ingrid N. |last2=Smith |first2=Thomas G. |last3=Bullock |first3=Ian D. |last4=Green |first4=Geoffrey D. |last5=Carlsson |first5=Olle G. L. |last6=Imberti |first6=Santiago |doi=10.1111/j.1748-7692.2007.00163.x |title=Antarctic peninsula killer whales (''Orcinus orca'') hunt seals and a penguin on floating ice |year=2008 |pages=225–234 |volume=24 |journal=Marine Mammal Science |url=http://www.grupofalco.com.ar/pedefes/Visser%20et%20al%202008.%20Antarctic%20killer%20whales%20on%20ice%20-%20Marine%20Mammals%20Science.pdf |issue=1 |bibcode=2008MMamS..24..225V |url-status=dead |archive-url=https://web.archive.org/web/20110531161550/http://www.grupofalco.com.ar/pedefes/Visser%20et%20al%202008.%20Antarctic%20killer%20whales%20on%20ice%20-%20Marine%20Mammals%20Science.pdf |archive-date=May 31, 2011 }}</ref>

In the [[Biography:Aleutian Islands|Aleutian Islands]], a decline in [[Biology:Sea otter|sea otter]] populations in the 1990s was controversially attributed by some scientists to orca predation, although with no direct evidence.<ref>Pinell, Nadine, et al. "[http://wildwhales.org/?p=132 Transient Killer Whales&nbsp;– Culprits in the Decline of Sea Otters in Western Alaska?] {{Webarchive|url=https://web.archive.org/web/20170630063238/http://wildwhales.org/?p=132 |date=June 30, 2017 }}" B.C. Cetacean Sightings Network, June 1, 2004. Retrieved March 13, 2010</ref> The decline of sea otters followed a decline in seal populations,{{efn|According to Baird,{{sfn|Baird|2002|p=23}} killer whales prefer harbour seals to sea lions and porpoises in some areas.}}<ref>[http://www.gi.alaska.edu/ScienceForum/ASF14/1418.html Killer Whales Develop a Taste For Sea Otters] {{Webarchive|url=https://web.archive.org/web/20151107004222/http://www2.gi.alaska.edu/ScienceForum/ASF14/1418.html |date=November 7, 2015 }} Ned Rozell, Article #1418, Alaska Science Forum, December 10, 1998. Retrieved February 26, 2010</ref> which in turn may be substitutes for their original prey, now decimated by industrial whaling.<ref>{{cite journal|last1=Springer|first1=A. M.|title=Sequential megafaunal collapse in the North Pacific Ocean: An ongoing legacy of industrial whaling?|journal=Proceedings of the National Academy of Sciences|volume=100|pages=12223–12228|year=2003|doi=10.1073/pnas.1635156100|issue=21|bibcode=2003PNAS..10012223S|pmid=14526101|pmc=218740|doi-access=free}}</ref><ref>{{cite journal|last1=Demaster|first1=D.|last2=Trites|first2=A.|last3=Clapham|first3=P.|last4=Mizroch|first4=S.|last5=Wade|first5=P. |last6=Small|first6=R.|last7=Hoef|first7=J.|title=The sequential megafaunal collapse hypothesis: Testing with existing data |journal=Progress in Oceanography|year=2006|doi=10.1016/j.pocean.2006.02.007|volume=68|issue=2–4|pages=329–342 |bibcode=2006PrOce..68..329D}}</ref><ref>{{cite journal|last1=Estes|first1=J. A.|last2=Doak|first2=D. F.|last3=Springer|first3=A. M.|last4=Williams|first4=T. M.|title=Causes and consequences of marine mammal population declines in southwest Alaska: a food-web perspective|journal=Philosophical Transactions of the Royal Society B: Biological Sciences|volume=364|pages=1647–1658|year=2009|doi=10.1098/rstb.2008.0231|issue=1524|pmid=19451116|pmc=2685424}}</ref> Orcas have been observed preying on [[Biology:Terrestrial animal|terrestrial mammals]], such as moose swimming between islands off the northwest coast of North America.{{sfn|Baird|2002|p=23}}<ref name="BairdBaird2006">{{cite book|first1=Robert W.|last1=Baird|first2=Robin W.|last2=Baird|title=Killer Whales of the World: Natural History and Conservation|url=https://books.google.com/books?id=Rjksm-5-ap4C&pg=PA23|access-date=February 2, 2011|date=August 31, 2006|publisher=Voyageur Press|isbn=978-0-7603-2654-1|pages=23–|archive-url=https://web.archive.org/web/20110721191653/http://books.google.com/books?id=Rjksm-5-ap4C&pg=PA23|archive-date=July 21, 2011|url-status=live}}</ref> Orca cannibalism has also been reported based on analysis of stomach contents, but this is likely to be the result of scavenging remains dumped by whalers.{{sfn|Baird|2002|p=124}} One orca was also attacked by its companions after being shot.<ref name="Jefferson et al. 1991"/> 

Orcas do consume seabirds but are more likely to kill and leave them uneaten. [[Biology:Penguin|Penguin]] species recorded as prey in Antarctic and sub-Antarctic waters include [[Biology:Gentoo penguin|gentoo penguin]]s, [[Biology:Chinstrap penguin|chinstrap penguin]]s, [[Biology:King penguin|king penguin]]s and rockhopper penguins.<ref>{{cite journal|last1=Pitman|first1=R. L.|last2=Durban|first2=J. W.|year=2010|title=Killer whale predation on penguins in Antarctica|journal=Polar Biology|volume=33|issue=11|pages=1589–1594|doi=10.1007/s00300-010-0853-5|bibcode=2010PoBio..33.1589P |s2cid=44055219 }}</ref> Orcas in many areas may prey on [[Biology:Cormorant|cormorant]]s and [[Biology:Gull|gull]]s.{{sfn|Baird|2002|p=14}} A captive orca at Marineland of Canada discovered it could regurgitate fish onto the surface, attracting sea gulls, and then eat the birds. Four others then learned to copy the behaviour.<ref>{{Cite news |agency=Associated Press |url=http://news.mongabay.com/2005/0907-ap.html |title=Whale uses fish as bait to catch seagulls then shares strategy with fellow orcas |date=September 7, 2005 |access-date=February 18, 2010 |archive-date=March 22, 2010 |archive-url=https://web.archive.org/web/20100322204614/http://news.mongabay.com/2005/0907-ap.html |url-status=live }}</ref>

==Behaviour==
[[File:Orca 2.jpg|thumb|right|Orcas, like this one near Alaska, commonly breach, often lifting their entire bodies out of the water.|alt=A killer whale leaping out of the water is about to land on its back.]]
Day-to-day orca behaviour generally consists of foraging, travelling, resting and socializing. Orcas frequently engage in surface behaviour such as breaching (jumping completely out of the water) and tail-slapping. These activities may have a variety of purposes, such as courtship, communication, dislodging [[Biology:Parasite|parasite]]s, or play. Spyhopping is a behaviour in which a whale holds its head above water to view its surroundings.{{sfn|Carwardine|2001|p=64}} Resident orcas swim alongside [[Biology:Porpoise|porpoise]]s and other [[Biology:Dolphin|dolphin]]s.<ref name="OCR 11-2019">{{cite news |last=Connelly |first=Laylan |title=Videos show killer whales frantically hunting for dolphins off San Clemente |publisher=The OCR |url=https://www.ocregister.com/2019/07/30/videos-show-killer-whales-in-a-frantic-hunt-for-dolphins-off-san-clemente/ |date=July 30, 2019 |access-date=November 24, 2019 |archive-date=December 10, 2019 |archive-url=https://web.archive.org/web/20191210204422/https://www.ocregister.com/2019/07/30/videos-show-killer-whales-in-a-frantic-hunt-for-dolphins-off-san-clemente/ |url-status=live }}</ref>

Orcas will engage in [[Biology:Surplus killing|surplus killing]], that is, killing that is not designed to be for food. As an example, a BBC film crew witnessed orca in British Columbia playing with a male [[Biology:Steller sea lion|Steller sea lion]] to exhaustion, but not eating it.<ref>{{Cite web|url=https://www.youtube.com/watch?v=3f-FsAUcqMs|title=Orcas Kill, But Not Just for Food (2:06)|website=YouTube|language=en|access-date=2 June 2023}}</ref>

===Social structure===
Orcas are notable for their complex societies. Only [[Biology:Elephant|elephant]]s and higher primates live in comparably complex [[Social:Social structure|social structure]]s.{{sfn|Heimlich|Boran|2001|p=35}} Due to orcas' complex social bonds, many marine experts have concerns about how humane it is to keep them in captivity.<ref>{{cite web |url=http://www.keepwhaleswild.org/ |title=Keep Whales Wild |publisher=Keep Whales Wild |date=January 14, 2011 |access-date=February 16, 2011 |url-status=dead |archive-url=https://web.archive.org/web/20101216065407/http://www.keepwhaleswild.org/ |archive-date=December 16, 2010 }}</ref>

Resident orcas in the eastern North Pacific live in particularly complex and stable social groups. Unlike any other known mammal social structure, resident whales live with their mothers for their entire lives. These family groups are based on matrilines consisting of the eldest female (matriarch) and her sons and daughters, and the descendants of her daughters, etc. The average size of a matriline is 5.5 animals. Because females can reach age 90, as many as four generations travel together. These matrilineal groups are highly stable. Individuals separate for only a few hours at a time, to mate or forage. With one exception, an orca named Luna, no permanent separation of an individual from a resident matriline has been recorded.{{sfn|NMFS|2005|p=12}}

[[File:Transient Orcas (3727711709).jpg|thumb|A pair of orcas in the Pacific Northwest]]
Closely related matrilines form loose aggregations called pods, usually consisting of one to four matrilines. Unlike matrilines, pods may separate for weeks or months at a time.{{sfn|NMFS|2005|p=12}} [[Biology:DNA|DNA]] testing indicates resident males nearly always mate with females from other pods.{{sfn|NMFS|2005|p=39}} Clans, the next level of resident social structure, are composed of pods with similar dialects, and common but older maternal heritage. Clan ranges overlap, mingling pods from different clans.{{sfn|NMFS|2005|p=12}} The highest association layer is the community, which consists of pods that regularly associate with each other but share no maternal relations or dialects.<ref>{{cite book|last1=Ford|first1= J. K. B.|last2=Ellis|first2= G. M.|last3=Balcomb|first3= K. C.|year=1999|title=Killer Whales: The Natural History and Genealogy of ''Orcinus orca'' in British Columbia and Washington State|publisher=University of British Columbia Press|page=25|isbn=978-0774804691}}</ref>

Transient pods are smaller than resident pods, typically consisting of an adult female and one or two of her offspring. Males typically maintain stronger relationships with their mothers than other females. These bonds can extend well into adulthood. Unlike residents, extended or permanent separation of transient offspring from natal matrilines is common, with juveniles and adults of both sexes participating. Some males become "rovers" and do not form long-term associations, occasionally joining groups that contain reproductive females.{{sfn|NMFS|2005|p=13}} As in resident clans, transient community members share an acoustic repertoire, although regional differences in vocalizations have been noted.{{sfn|NMFS|2005|p=14}}

As with residents and transients, the lifestyle of these whales appears to reflect their diet; fish-eating orcas off Norway have resident-like social structures, while mammal-eating orcas in Argentina and the Crozet Islands behave more like transients.{{sfn|Ford|Ellis|Balcomb|2000|p=27}}

Orcas of the same sex and age group may engage in physical contact and synchronous surfacing. These behaviours do not occur randomly among individuals in a pod, providing evidence of "friendships".<ref>{{cite journal|author=Weiss|first1= M. N.|display-authors=0|year=2021|title=Age and sex influence social interactions, but not associations, within a killer whale pod|journal=Proceedings of the Royal Society B: Biological Sciences|volume=288|issue=1953|doi=10.1098/rspb.2021.0617|pmid=34130498|pmc=8206696|hdl=10871/125706|hdl-access=free}}</ref><ref>{{cite journal|author=Lesté-Lasserre|first1= Christa|date=June 17, 2021|title=Killer whales form killer friendships, new drone footage suggests|journal=Science|url=https://www.science.org/content/article/killer-whales-form-killer-friendships-new-drone-footage-suggests|access-date=June 18, 2021}}</ref>

===Vocalizations===
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{{See also|Whale vocalization{{!}}Whale sound}}
Like all cetaceans, orcas depend heavily on underwater sound for orientation, feeding, and communication. They produce three categories of sounds: clicks, whistles, and pulsed calls. Clicks are believed to be used primarily for navigation and discriminating prey and other objects in the surrounding environment, but are also commonly heard during social interactions.<ref name=noaa/>

Northeast Pacific resident groups tend to be much more vocal than transient groups in the same waters.{{sfn|NMFS|2005|p=20}} Residents feed primarily on [[Biology:Chinook salmon|Chinook]] and [[Biology:Chum salmon|chum]] salmon, which are insensitive to orca calls (inferred from the audiogram of Atlantic salmon). In contrast, the [[Biology:Marine mammal|marine mammal]] prey of transients hear whale calls well and thus transients are typically silent.{{sfn|NMFS|2005|p=20}} Vocal behaviour in these whales is mainly limited to surfacing activities and milling (slow swimming with no apparent direction) after a kill.<ref>{{cite journal|last1=Deeck|first1= V. B.|last2=Ford|first2= J. K. B.|last3=Slater|first3= P. J. B.|year=2005|title=The vocal behaviour of mammal-eating killer whales: communicating with costly calls|journal=Animal Behaviour|volume=69|issue=2|pages=395–405|doi=10.1016/j.anbehav.2004.04.014|s2cid=16899659}}</ref>

All members of a resident pod use similar calls, known collectively as a [[Social:Dialect|dialect]]. Dialects are composed of specific numbers and types of discrete, repetitive calls. They are complex and stable over time.<ref>{{cite journal|author=Foote|first1= A. D.|last2=Osborne|first2= R. W.|last3=Hoelzel|first3= A.|year=2008|title=Temporal and contextual patterns of killer whale (''Orcinus orca'') call type production|journal=Ethology|volume=114|issue=6|pages=599–606|doi=10.1111/j.1439-0310.2008.01496.x|bibcode= 2008Ethol.114..599F}}</ref> Call patterns and structure are distinctive within matrilines.<ref name=vocal/> Newborns produce calls similar to their mothers, but have a more limited repertoire.{{sfn|NMFS|2005|p=14}} Individuals likely learn their dialect through contact with pod members.<ref>{{cite journal|last1=Filatova|first1= Olga A.|last2=Fedutin|first2= Ivan D.|last3=Burdin|first3= Alexandr M.|last4=Hoyt|first4= Erich|year=2007|url=http://russianorca.com/Doc/Science/structure_repert.pdf|title=The structure of the discrete call repertoire of killer whales ''Orcinus orca'' from Southeast Kamchatka|journal=Bioacoustics|volume=16|pages=261–280|doi=10.1080/09524622.2007.9753581|issue=3|bibcode= 2007Bioac..16..261F|s2cid=56304541|access-date=February 23, 2010|archive-date=July 15, 2011|archive-url=https://web.archive.org/web/20110715214729/http://russianorca.com/Doc/Science/structure_repert.pdf|url-status=live}}</ref> Family-specific calls have been observed more frequently in the days following a calf's birth, which may help the calf learn them.<ref>{{cite journal|url=http://www.coloradocollege.edu/dept/ev/Research/Faculty/OVALItems/pdf_Papers/SpongCalvesPaper.pdf |archive-url=https://web.archive.org/web/20110527060306/http://www.coloradocollege.edu/dept/ev/Research/Faculty/OVALItems/pdf_Papers/SpongCalvesPaper.pdf |archive-date=May 27, 2011 |last1=Weiß |first1=Brigitte M. |journal=The Journal of the Acoustical Society of America |volume=119 |last2=Ladich |issue=1 |first2=Friedrich |last3=Spong |first3=Paul |last4=Symonds |first4=Helena |year=2006 |pmid=16454316 |title=Vocal behaviour of resident killer whale matrilines with newborn calves: The role of family signatures |doi=10.1121/1.2130934 |pages=627–635 |bibcode=2006ASAJ..119..627W |url-status=dead }}</ref> Dialects are probably an important means of maintaining group identity and cohesiveness. Similarity in dialects likely reflects the degree of relatedness between pods, with variation growing over time.{{sfn|NMFS|2005|pp=15–16}} When pods meet, dominant call types decrease and subset call types increase. The use of both call types is called biphonation. The increased subset call types may be the distinguishing factor between pods and inter-pod relations.<ref name=vocal>{{cite journal|author=Kremers|first1= D.|last2=Lemasson|first2= A.|last3=Almunia|first3= J.|last4=Wanker|first4= R.|year=2012|title=Vocal sharing and individual acoustic distinctiveness within a group of captive orcas (''Orcinus orca'')|journal=Journal of Comparative Psychology|volume=126|issue=4|pages=433–445|doi=10.1037/a0028858|pmid=22866769}}</ref>

Dialects also distinguish types. Resident dialects contain seven to 17 (mean = 11) distinctive call types. All members of the North American west coast transient community express the same basic dialect, although minor regional variation in call types is evident. Preliminary research indicates offshore orcas have group-specific dialects unlike those of residents and transients.{{sfn|NMFS|2005|pp=15–16}}

Norwegian and Icelandic [[Biology:Herring|herring]]-eating orcas appear to have different vocalizations for activities like hunting.<ref>{{cite journal|author=Simon|first1= M.|last2=McGregor|first2= P. K.|last3=Ugarte|first3= F.|year=2007|title=The relationship between the acoustic behaviour and surface activity of killer whales (''Orcinus orca'') that feed on herring (''Clupea harengus'')|journal=Acta Ethologica|volume=10|issue=2|pages=47–53|doi=10.1007/s10211-007-0029-7|s2cid=29828311}}</ref> A population that live in McMurdo Sound, [[Earth:Antarctica|Antarctica]] have 28 complex burst-pulse and whistle calls.<ref>{{Cite web|url=https://newatlas.com/science/smallest-killer-whale-large-musical-repertoire/|title=The smallest killer whale has a large musical repertoire|last=Szondy|first=David|date=February 26, 2020|website=New Atlas|language=en-US|url-status=live|access-date=February 27, 2020|archive-date=February 27, 2020|archive-url=https://web.archive.org/web/20200227234559/https://newatlas.com/science/smallest-killer-whale-large-musical-repertoire/}}</ref>

===Intelligence===
Orcas have the second-heaviest brains among marine mammals<ref name=spear>{{cite news|last=Spear|first= Kevin|url=http://articles.orlandosentinel.com/2010-03-06/news/os-seaworld-killer-whale-brains-20100302_1_killer-whales-orcas-dolphin-or-porpoise |title=Killer whales: How smart are they?|archive-url=https://web.archive.org/web/20150908001401/http://articles.orlandosentinel.com/2010-03-06/news/os-seaworld-killer-whale-brains-20100302_1_killer-whales-orcas-dolphin-or-porpoise |archive-date=September 8, 2015 |work=Orlando Sentinel|date= March 7, 2010|access-date= March 7, 2010}}</ref> (after [[Biology:Sperm whale|sperm whale]]s, which have the largest brain of any animal).<ref>{{Cite news|last=Dunham|first=Will|date=2017-10-16|title=Big and brilliant: complex whale behavior tied to brain size|language=en|work=Reuters|url=https://www.reuters.com/article/us-science-whales-idUSKBN1CL30I|access-date=2020-12-23}}</ref> Orcas have more [[Biology:Grey matter|gray matter]] and more cortical neurons than any mammal, including humans.<ref>{{Cite journal |last1=Ridgway |first1=Sam H. |last2=Brownson |first2=Robert H. |last3=Van Alstyne |first3=Kaitlin R. |last4=Hauser |first4=Robert A. |date=2019-12-16 |editor-last=Li |editor-first=Songhai |title=Higher neuron densities in the cerebral cortex and larger cerebellums may limit dive times of delphinids compared to deep-diving toothed whales |journal=PLOS ONE |language=en |volume=14 |issue=12 |pages=e0226206 |doi=10.1371/journal.pone.0226206 |issn=1932-6203 |pmc=6914331 |pmid=31841529 |bibcode=2019PLoSO..1426206R |doi-access=free }}</ref> They can be trained in captivity and are often described as intelligent,<ref name=cbs2010/>{{sfn|Carwardine|2001|p=67}} although defining and measuring "intelligence" is difficult in a species whose environment and behavioural strategies are very different from those of humans.{{sfn|Carwardine|2001|p=67}} Orcas imitate others, and seem to deliberately teach skills to their kin. Off the Crozet Islands, mothers push their calves onto the beach, waiting to pull the youngster back if needed.{{sfn|Heimlich|Boran|2001|p=45}}{{sfn|Baird|2002|pp=61–62}} In March 2023, a female orca was spotted with a newborn [[Biology:Pilot whale|pilot whale]] in Snæfellsnes.<ref>{{cite news | url=https://www.theguardian.com/environment/2023/mar/10/killer-whale-orca-adopts-abducts-pilot-whale-calf-aoe | title='Extraordinary' sighting of orca with baby pilot whale astounds scientists | newspaper=The Guardian | date=March 10, 2023 | last1=Weston | first1=Phoebe }}</ref>

[[File:Orca with iceball cropped.JPG|thumb|An orca plays with a ball of ice, soon after a researcher threw a snowball at the whale.]]
People who have interacted closely with orcas offer numerous [[Anecdotal evidence|anecdotes]] demonstrating the whales' curiosity, playfulness, and ability to solve problems. Alaskan orcas have not only learned how to steal fish from longlines, but have also overcome a variety of techniques designed to stop them, such as the use of unbaited lines as decoys.{{sfn|Obee|Ellis|1992|p=42}} Once, fishermen placed their boats several miles apart, taking turns retrieving small amounts of their catch, in the hope that the whales would not have enough time to move between boats to steal the catch as it was being retrieved. The tactic worked initially, but the orcas figured it out quickly and split into groups.{{sfn|Obee|Ellis|1992|p=42}}

In other anecdotes, researchers describe incidents in which wild orcas playfully tease humans by repeatedly moving objects the humans are trying to reach,<ref name=BF>{{Cite journal |year=2005 |title=Killer whale games |journal=Blackfish Sounder |volume=13 |page=5 |url=http://www.killerwhale.org/BFS/BFS_13.pdf |archive-url=https://web.archive.org/web/20071011062137/http://www.killerwhale.org/BFS/BFS_13.pdf |archive-date=October 11, 2007 |url-status=dead}}</ref> or suddenly start to toss around a chunk of ice after a human throws a snowball.<ref>Pitman, Robert L. [http://www.livescience.com/animals/090206-nhm-killer-whale-snowball.html Scientist Has 'Snowball Fight' With a Killer Whale] {{Webarchive|url=https://web.archive.org/web/20200915041640/https://www.livescience.com/3284-scientist-snowball-fight-killer-whale.html |date=September 15, 2020 }}. ''Live Science'', February 6, 2009. Retrieved March 7, 2010</ref>

The orca's use of dialects and the passing of other learned behaviours from generation to generation have been described as a form of [[Biology:Animal culture|animal culture]].<ref>{{Cite journal |doi=10.1371/journal.pbio.0050139 |last=Marino |first=Lori |title=Cetaceans Have Complex Brains for Complex Cognition |journal=[[Biology:PLOS Biology|PLOS Biology]] |year=2007 |page=e139 |volume=5 |issue=e139 |pmid=17503965 |pmc=1868071 |display-authors=0 |doi-access=free }}</ref>

{{blockquote|The complex and stable vocal and behavioural cultures of [[Earth:Sympatry|sympatric]] groups of killer whales (''Orcinus orca'') appear to have no parallel outside humans and represent an independent evolution of cultural faculties.<ref name=rendell>{{cite journal|last1=Rendell|first1= Luke|first2=Hal|last2= Whitehead|url=http://whitelab.biology.dal.ca/lr/bbs.htm|title=Culture in whales and dolphins|journal=Behavioral and Brain Sciences|year=2001|volume=24|issue=2|pages=309–324|access-date=March 7, 2010|pmid=11530544|doi=10.1017/S0140525X0100396X|s2cid=24052064|archive-date=May 30, 2010|archive-url=https://web.archive.org/web/20100530054246/http://whitelab.biology.dal.ca/lr/bbs.htm|url-status=live}}</ref>}}

==Life cycle==
[[File:091201 south georgia orca 5227 (4173390858).jpg|thumb|Adult female orca with calf near South Georgia]]
Female orcas begin to mature at around the age of 10 and reach peak fertility around 20,<ref name=Reproduction>{{cite journal |last1=Ward |first1=Eric J. |last2=Holmes |first2=Elizabeth E. |last3=Balcomb |first3=Ken C. |title=Quantifying the effects of prey abundance on killer whale reproduction |journal=Journal of Applied Ecology |date=June 2009 |volume=46 |issue=3 |pages=632–640 |doi=10.1111/j.1365-2664.2009.01647.x|doi-access=free |bibcode=2009JApEc..46..632W }}</ref> experiencing periods of polyestrous cycling separated by non-cycling periods of three to 16 months. Females can often breed until age 40, followed by a rapid decrease in fertility.<ref name=Reproduction /> Orcas are among the few [[Medicine:Menopause#Other animals|animals that undergo menopause]] and live for decades after they have finished breeding.<ref>{{cite journal |last1=Bowden |first1=D. M. |last2=Williams |first2=D. D. |title=Aging |journal=Advances in Veterinary Science and Comparative Medicine |date=1984 |volume=28 |pages=305–341 |pmid=6395674 |doi=10.1016/B978-0-12-039228-5.50015-2 |isbn=9780120392285}}</ref><ref>{{cite book|title=Physiological Basis of Aging and Geriatrics|edition= Fourth|first1=Paola S.|last1= Timiras|publisher= CRC Press|date= 2013| page= 161}}</ref> The lifespans of wild females average 50 to 80 years.<ref name="nationalgeographic.com">{{cite web |title=Orcas don't do well in captivity. Here's why. |url=https://www.nationalgeographic.com/animals/2019/03/orcas-captivity-welfare/ |website=Animals |access-date=31 May 2020 |language=en |date=25 March 2019 |archive-date=June 6, 2020 |archive-url=https://web.archive.org/web/20200606082028/https://www.nationalgeographic.com/animals/2019/03/orcas-captivity-welfare/ |url-status=dead }}</ref> Some are claimed to have lived substantially longer: Granny (J2) was estimated by some researchers to have been as old as 105 years at the time of her death, though a biopsy sample indicated her age as 65 to 80 years.{{sfn|Carwardine|2001|p=26}}<ref name=King>{{Cite news|url=http://www.king5.com/news/local/oldest-southern-resident-killer-whale-considered-dead/381349614|title=Oldest Southern Resident killer whale considered dead|last=TEGNA|newspaper=KING|language=en-US|access-date=January 3, 2017|archive-date=January 3, 2017|archive-url=https://web.archive.org/web/20170103094218/http://www.king5.com/news/local/oldest-southern-resident-killer-whale-considered-dead/381349614|url-status=live}}</ref><ref name="Orcazine">{{cite web|url=http://orcazine.com/granny-j2/|title=Orca Granny: was she really 105?|last=Podt|first=Annemieke|language=en-US|access-date=September 11, 2017|date=December 31, 2016|archive-date=October 15, 2018|archive-url=https://web.archive.org/web/20181015152227/http://orcazine.com/granny-j2/|url-status=live}}</ref> It is thought that orcas held in captivity tend to have shorter lives than those in the wild, although this is subject to scientific debate.<ref name="nationalgeographic.com"/><ref name=robeck>{{cite journal |last1=Robeck |first1=Todd R. |last2=Willis |first2=Kevin |last3=Scarpuzzi |first3=Michael R. |last4=O'Brien |first4=Justine K. |title=Comparisons of life-history parameters between free-ranging and captive killer whale (''Orcinus orca'') populations for application toward species management |url=https://academic.oup.com/jmammal/article/96/5/1055/920547|journal=Journal of Mammalogy |pages=1055–1070 |language=en |doi=10.1093/jmammal/gyv113 |date=29 September 2015 |volume=96 |issue=5 |pmid=26937049 |pmc=4668992 |archive-date=April 23, 2019 |archive-url=https://web.archive.org/web/20190423085700/https://academic.oup.com/jmammal/article/96/5/1055/920547 |url-status=dead }}</ref><ref>{{cite journal |last1=Jett |first1=John |last2=Ventre |first2=Jeffrey |title=Captive killer whale (''Orcinus orca'') survival |journal=Marine Mammal Science |pages=1362–1377 |language=en |doi=10.1111/mms.12225 |date=2015 |volume=31|issue=4 |bibcode=2015MMamS..31.1362J }}</ref>

Males mate with females from other pods, which prevents [[Biology:Inbreeding|inbreeding]]. Gestation varies from 15 to 18 months. {{sfn|NMFS|2005|p=33}} Mothers usually calve a single offspring about once every five years. In resident pods, births occur at any time of year, although winter is the most common. Mortality is extremely high during the first seven months of life, when 37–50% of all calves die.{{sfn|NMFS|2005|p=35}} Weaning begins at about 12 months of age, and is complete by two years. According to observations in several regions, all male and female pod members participate in the care of the young.{{sfn|Heimlich|Boran|2001|p=35}}

Males sexually mature at the age of 15, but do not typically reproduce until age 21. Wild males live around 29 years on average, with a maximum of about 60 years.{{sfn|Carwardine|2001|p=26}} One male, known as Old Tom, was reportedly spotted every winter between the 1840s and 1930 off New South Wales, Australia, which would have made him up to 90 years old. Examination of his teeth indicated he died around age 35,<ref>Mitchell, E. and Baker, A. N. (1980). Age of reputedly old Killer Whale, ''Orcinus orca'', 'Old Tom' from Eden, Twofold Bay, Australia, in: W. F. Perrin and A. C. Myrick Jr (eds.): Age determination of toothed whales and sirenians, pp. 143–154 Rep. Int. Whal. Comm. (Special Issue 3), cited in [https://web.archive.org/web/20061014152551/http://www.t-d-e.org/knowkillerwhale.php Know the Killer Whale], The Dolphin's Encyclopaedia. Retrieved January 27, 2010</ref> but this method of age determination is now believed to be inaccurate for older animals.<ref>Olesiuk, Peter F.; Ellis, Graeme M. and Ford, John K. B. (2005). [http://www.pac.dfo-mpo.gc.ca/science/species-especes/cetacean-cetaces/CRP-publications/Olesiuk%20et%20al.%202005%20KW%20Pop%20Dyn.pdf Life History and Population Dynamics of Northern Resident Killer Whales (''Orcinus orca'') in British Columbia] {{webarchive|url=https://web.archive.org/web/20110419074348/http://www.pac.dfo-mpo.gc.ca/science/species-especes/cetacean-cetaces/CRP-publications/Olesiuk%20et%20al.%202005%20KW%20Pop%20Dyn.pdf |date=April 19, 2011 }}, Research Document 2005/045, Canadian Science Advisory Secretariat, Fisheries and Oceans Canada. p. 33. Retrieved January 27, 2010</ref> One male known to researchers in the [[Place:Pacific Northwest|Pacific Northwest]] (identified as J1) was estimated to have been 59 years old when he died in 2010.<ref>[http://www.whaleresearch.com/orca_ID.html How Southern Resident Killer Whales are Identified] {{webarchive|url=https://web.archive.org/web/20091128230801/http://www.whaleresearch.com/orca_ID.html |date=November 28, 2009 }}, Center for Whale Research. Retrieved March 23, 2012</ref> Orcas are unique among cetaceans, as their caudal sections elongate with age, making their heads relatively shorter.{{sfn|Heptner|Nasimovich|Bannikov|Hoffmann|1996|p=681}}

[[Biology:Infanticide (zoology)|Infanticide]], once thought to occur only in captive orcas, was observed in wild populations by researchers off British Columbia on December 2, 2016. In this incident, an adult male killed the calf of a female within the same pod, with the adult male's mother also joining in the assault. It is theorized that the male killed the young calf in order to mate with its mother (something that occurs in other carnivore species), while the male's mother supported the breeding opportunity for her son. The attack ended when the calf's mother struck and injured the attacking male. Such behaviour matches that of many smaller dolphin species, such as the [[Biology:Bottlenose dolphin|bottlenose dolphin]].<ref>{{Cite web | url=http://www.cbc.ca/news/canada/british-columbia/killer-whale-infanticide-1.4586867 | title='Horrified' scientists first to see killer whale infanticide &#124; CBC News | access-date=March 22, 2018 | archive-date=March 23, 2018 | archive-url=https://web.archive.org/web/20180323025412/http://www.cbc.ca/news/canada/british-columbia/killer-whale-infanticide-1.4586867 | url-status=live }}</ref>

==Conservation==
[[File:TypeC orca cape.JPG|thumb|right|The "type C" orca has two-toned grey colouring, including a dark "dorsal cape", in body areas where most orcas have solid black colouring. Research is ongoing into whether one or more orca types are distinct species in need of protection.|alt=Killer whale forges through small ice floes. Its back is dark from the head to just behind the dorsal fin, where there is a light grey saddle patch. Behind this, and on its lower side, its skin is an intermediate shade.]]
In 2008, the IUCN (International Union for Conservation of Nature) changed its assessment of the orca's [[Biology:Conservation status|conservation status]] from conservation dependent to [[Biology:Data deficient|data deficient]], recognizing that one or more orca types may actually be separate, [[Biology:Endangered species|endangered species]].<ref name="iucn status 19 November 2021" /> Depletion of prey species, [[Earth:Marine pollution|pollution]], large-scale [[Earth:Oil spill|oil spill]]s, and [[Earth:Disturbance (ecology)|habitat disturbance]] caused by noise and conflicts with boats are the most significant worldwide threats.<ref name="iucn status 19 November 2021" /> In January 2020, the first orca in England and Wales since 2001 was found dead with a large fragment of plastic in its stomach.<ref>{{Cite web|url=https://www.bbc.com/news/uk-england-norfolk-51108830|title=First stranded Orca found in almost 20 years in the Wash|date=January 14, 2020|website=BBC News|url-status=live|archive-date=January 16, 2020|archive-url=https://web.archive.org/web/20200116204509/https://www.bbc.com/news/uk-england-norfolk-51108830}}</ref>

Like other animals at the highest [[Earth:Trophic level|trophic level]]s, the orca is particularly at risk of poisoning from bioaccumulation of toxins, including [[Chemistry:Polychlorinated biphenyl|Polychlorinated biphenyl]]s (PCBs).{{sfn|Ford|Ellis|Balcomb|2000|p=99}} European harbour seals have problems in reproductive and immune functions associated with high levels of PCBs and related contaminants, and a survey off the {{wipe|Washington (state)}} coast found PCB levels in orcas were higher than levels that had caused health problems in harbour seals.{{sfn|Ford|Ellis|Balcomb|2000|p=99}} Blubber samples in the Norwegian Arctic show higher levels of PCBs, pesticides and brominated flame-retardants than in [[Biology:Polar bear|polar bear]]s. A 2018 study published in ''Science'' found that global orca populations are poised to dramatically decline due such toxic pollution.<ref>{{cite news |last=Carrington |first=Damian |date=September 27, 2018 |title=Orca 'apocalypse': half of killer whales doomed to die from pollution |url=https://www.theguardian.com/environment/2018/sep/27/orca-apocalypse-half-of-killer-whales-doomed-to-die-from-pollution |work=The Guardian |access-date=September 28, 2018 |archive-date=September 28, 2018 |archive-url=https://web.archive.org/web/20180928005643/https://www.theguardian.com/environment/2018/sep/27/orca-apocalypse-half-of-killer-whales-doomed-to-die-from-pollution |url-status=live }}</ref><ref>{{cite journal|last1=Desforges|first1=J-P|last2=Hall|first2=A|last3=Mcconnell|first3=B|display-authors=0|year=2018|title=Predicting global killer whale population collapse from PCB pollution|journal=Science|volume=361|issue=6409|pages=1373–1376|doi=10.1126/science.aat1953|pmid=30262502 |bibcode=2018Sci...361.1373D |hdl=10023/16189 |s2cid=52876312 |hdl-access=free}}</ref>

In the [[Place:Pacific Northwest|Pacific Northwest]], wild salmon stocks, a main resident food source, have declined dramatically in recent years.<ref name="iucn status 19 November 2021" /> In the Puget Sound region, only 75 whales remain with few births over the last few years.<ref>{{Cite news|url=https://www.nytimes.com/2018/07/09/science/orcas-whales-endangered.html?rref=collection/sectioncollection/science&action=click&contentCollection=science&region=rank&module=package&version=highlights&contentPlacement=1&pgtype=sectionfront|title=Orcas of the Pacific Northwest Are Starving and Disappearing|newspaper=The New York Times |date=July 9, 2018 |access-date=July 9, 2018|language=en|archive-date=July 10, 2018|archive-url=https://web.archive.org/web/20180710011739/https://www.nytimes.com/2018/07/09/science/orcas-whales-endangered.html?rref=collection%2Fsectioncollection%2Fscience&action=click&contentCollection=science&region=rank&module=package&version=highlights&contentPlacement=1&pgtype=sectionfront|url-status=live|last1=Robbins |first1=Jim }}</ref> On the west coast of Alaska and the [[Biography:Aleutian Islands|Aleutian Islands]], seal and sea lion populations have also substantially declined.{{sfn|Ford|Ellis|Balcomb|2000|p=98}}

In 2005, the United States government listed the [[Biology:Southern resident killer whales|southern resident]] community as an endangered population under the Endangered Species Act.<ref name=noaa/> This community comprises three pods which live mostly in the Georgia and Haro Straits and Puget Sound in British Columbia and Washington. They do not breed outside of their community, which was once estimated at around 200 animals and later shrank to around 90.<ref name=Lyke>{{cite news|first=M. L.|last= Lyke|url=http://www.seattlepi.com/specials/brokenpromises/288674_granny614.html|title= Granny's Struggle: When Granny is gone, will her story be the last chapter?|archive-url=https://web.archive.org/web/20200915041546/https://www.seattlepi.com/news/article/Granny-s-Struggle-When-Granny-is-gone-will-her-1217200.php |archive-date=September 15, 2020|work=Seattle Post Intelligencer|date= October 14, 2006}}</ref> In October 2008, the annual survey revealed seven were missing and presumed dead, reducing the count to 83.<ref name=researchers/> This is potentially the largest decline in the population in the past 10 years. These deaths can be attributed to declines in [[Biology:Chinook salmon|Chinook salmon]].<ref name=researchers>Le Phuong. [https://www.usatoday.com/news/nation/environment/2008-10-25-orcas-puget-sound_N.htm Researchers: 7 Orcas Missing from Puget Sound] {{Webarchive|url=https://web.archive.org/web/20081028085210/http://www.usatoday.com/news/nation/environment/2008-10-25-orcas-puget-sound_N.htm |date=October 28, 2008 }}, Associated Press. USA Today, October 25, 2008</ref>

Scientist Ken Balcomb has extensively studied orcas since 1976; he is the research biologist responsible for discovering U.S. Navy sonar may harm orcas. He studied orcas from the Center for Whale Research, located in Friday Harbor, Washington.<ref name = Pickrell>{{cite news|last=Pickrell|first=John|title=U.S. Navy Sonar May Harm Killer Whales, Expert Says.|url=http://news.nationalgeographic.com/news/2004/03/0331_040331_whalesincrisis.html|access-date=March 19, 2012|newspaper=National Geographic News|date=March 2004|archive-date=September 9, 2011|archive-url=https://web.archive.org/web/20110909000831/http://news.nationalgeographic.com/news/2004/03/0331_040331_whalesincrisis.html|url-status=dead}}</ref> He was also able to study orcas from "his home porch perched above Puget Sound, where the animals hunt and play in summer months".<ref name = Pickrell/> In May 2003, Balcomb (along with other whale watchers near the Puget Sound coastline) noticed uncharacteristic behaviour displayed by the orcas. The whales seemed "agitated and were moving haphazardly, attempting to lift their heads free of the water" to escape the sound of the sonars.<ref name = Pickrell/> "Balcomb confirmed at the time that strange underwater pinging noises detected with underwater microphones were sonar. The sound originated from a U.S. Navy frigate 12 miles (19 kilometres) distant, Balcomb said."<ref name = Pickrell/> The impact of sonar waves on orcas is potentially life-threatening. Three years prior to Balcomb's discovery, research in the Bahamas showed 14 beaked whales washed up on the shore. These whales were beached on the day U.S. Navy destroyers were activated into sonar exercise.<ref name = Pickrell/> Of the 14 whales beached, six of them died. These six dead whales were studied, and CAT scans of two of the whale heads showed hemorrhaging around the brain and the ears, which is consistent with [[Medicine:Decompression sickness|decompression sickness]].<ref name = Pickrell/>

Another conservation concern was made public in September 2008 when the Canadian government decided it was not necessary to enforce further protections (including the [[Biology:Species at Risk Act|Species at Risk Act]] in place to protect endangered animals along with their habitats) for orcas aside from the laws already in place. In response to this decision, six environmental groups sued the federal government, claiming orcas were facing many threats on the British Columbia Coast and the federal government did nothing to protect them from these threats.<ref name = CBC>{{cite news|title=Ottawa Sued over Lack of Legislation to Protect B.C. Killer Whales|url=http://www.cbc.ca/news/canada/british-columbia/story/2008/10/08/bc-killer-whale-lawsuit.html|access-date=March 19, 2012|newspaper=CBC News|date=October 9, 2008|archive-date=June 26, 2012|archive-url=https://web.archive.org/web/20120626200949/http://www.cbc.ca/news/canada/british-columbia/story/2008/10/08/bc-killer-whale-lawsuit.html|url-status=live}}</ref> A legal and scientific nonprofit organization, Ecojustice, led the lawsuit and represented the David Suzuki Foundation, Environmental Defence, Greenpeace Canada, International Fund for Animal Welfare, the Raincoast Conservation Foundation, and the Wilderness Committee.<ref name = CBC/> Many scientists involved in this lawsuit, including Bill Wareham, a marine scientist with the David Suzuki Foundation, noted increased boat traffic, water toxic wastes, and low salmon population as major threats, putting approximately 87 orcas on the British Columbia Coast in danger.<ref name = CBC/>

[[Physics:Underwater acoustics|Underwater noise]] from shipping, drilling, and other human activities is a significant concern in some key orca habitats, including Johnstone Strait and Haro Strait.{{sfn|Ford|Ellis|Balcomb|2000|p=100}} In the mid-1990s, loud underwater noises from salmon farms were used to deter seals. Orcas also avoided the surrounding waters.<ref>
[http://www.raincoastresearch.org/orca.htm Research on Orcas] {{webarchive|url=https://archive.today/20120911041805/http://www.raincoastresearch.org/orca.htm |date=September 11, 2012 }}, Raincoast Research Society. Retrieved February 18, 2010</ref> High-intensity sonar used by the Navy disturbs orcas along with other marine mammals.<ref>{{Cite news|last=McClure|first=Robert|title=State expert urges Navy to stop sonar tests|url=http://www.seattlepi.com/local/article/State-expert-urges-Navy-to-stop-sonar-tests-1125871.php|work=Seattle Post Intelligencer|date=October 2, 2003|access-date=June 25, 2007|archive-date=October 4, 2012|archive-url=https://web.archive.org/web/20121004152333/http://www.seattlepi.com/local/article/State-expert-urges-Navy-to-stop-sonar-tests-1125871.php|url-status=live}}</ref> Orcas are popular with whale watchers, which may stress the whales and alter their behaviour, particularly if boats approach too closely or block their lines of travel.<ref>{{cite journal |last=Williams |first=Rob |title=Behavioural responses of male killer whales to a 'leapfrogging' vessel |journal=Journal of Cetacean Research and Management|volume=4 |issue=3 |pages=305–310 |year=2023 |doi=10.47536/jcrm.v4i3.844 |s2cid=55958971 |url=http://www.nwfsc.noaa.gov/research/divisions/cb/ecosystem/marinemammal/kwworkshops/boatpubs/leapfrogging_williamsetal.pdf |access-date=February 25, 2014 |archive-date=March 6, 2014 |archive-url=https://web.archive.org/web/20140306170841/http://www.nwfsc.noaa.gov/research/divisions/cb/ecosystem/marinemammal/kwworkshops/boatpubs/leapfrogging_williamsetal.pdf |url-status=live }}</ref>

The ''Exxon Valdez'' oil spill adversely affected orcas in Prince William Sound and Alaska's Kenai Fjords region. Eleven members (about half) of one resident pod disappeared in the following year. The spill damaged salmon and other prey populations, which in turn damaged local orcas. By 2009, scientists estimated the AT1 transient population (considered part of a larger population of 346 transients), numbered only seven individuals and had not reproduced since the spill. This population is expected to die out.<ref>{{cite magazine |url=https://www.wired.com/wiredscience/2009/03/valdezwhales/ |title=Unique Killer-Whale Pod Doomed by Exxon Valdez |magazine=Wired |access-date=December 31, 2009 |first=Brandon |last=Keim |date=March 24, 2009 |archive-date=January 6, 2010 |archive-url=https://web.archive.org/web/20100106190509/http://www.wired.com/wiredscience/2009/03/valdezwhales/ |url-status=live }}</ref><ref>{{cite web |url=http://www.whalesalaska.org/docs/m356p269.pdf |title=Marine Ecology Progress Series 356:269 |access-date=December 31, 2009 |url-status=dead |archive-url=https://web.archive.org/web/20110728174630/http://www.whalesalaska.org/docs/m356p269.pdf |archive-date=July 28, 2011 }}</ref>

Orcas are included in Appendix II of the Convention on International Trade in Endangered Species (CITES), meaning international trade (including in parts/derivatives) is regulated.<ref name = "CITES"/>

==Relationship with humans==

===Indigenous cultures===
[[File:Haida Jade.jpg|thumb|upright|Haida sculpture by Bill Reid|alt=Jade carving of a killer whale with exaggerated fins and bared teeth. Its body and fins are engraved with nested ovals and other patterns.]]

The indigenous peoples of the Pacific Northwest Coast feature orcas throughout their art, history, spirituality and religion. The Haida regarded orcas as the most powerful animals in the ocean, and their mythology tells of orcas living in houses and towns under the sea. According to these myths, they took on human form when submerged, and humans who drowned went to live with them.{{sfn|Francis|Hewlett|2007|pp=115–120}} For the Kwakwaka'wakw, the orca was regarded as the ruler of the undersea world, with [[Biology:Sea lion|sea lion]]s for slaves and dolphins for warriors.{{sfn|Francis|Hewlett|2007|pp=115–120}} In Nuu-chah-nulth and Kwakwaka'wakw mythology, orcas may embody the souls of deceased chiefs.{{sfn|Francis|Hewlett|2007|pp=115–120}} The Tlingit of southeastern Alaska regarded the orca as custodian of the sea and a benefactor of humans.{{sfn|Ford|Ellis|Balcomb|2000|p=11}}
The Lummi consider orca to be people, referring to them as "qwe'lhol'mechen" which means "our relations under the waves".<ref>{{cite news |last1=Gibson |first1=Caitlin |title=The call of Tokitae |url=https://www.washingtonpost.com/lifestyle/interactive/2023/tokitae-lolita-orca/ |newspaper={{wipe|The Washington Post}} |access-date=December 10, 2023 |date=December 5, 2023 |archive-date=December 5, 2023 |archive-url=https://web.archive.org/web/20231205234228/https://www.washingtonpost.com/lifestyle/interactive/2023/tokitae-lolita-orca/ |url-status=live }}</ref>

The Maritime Archaic people of Newfoundland also had great respect for orcas, as evidenced by stone carvings found in a 4,000-year-old burial at the Port au Choix Archaeological Site.<ref>Rollmann, Hans (1999). [http://www.heritage.nf.ca/society/religion.html Religion in Newfoundland and Labrador] {{Webarchive|url=https://web.archive.org/web/20090504120020/http://www.heritage.nf.ca/society/religion.html |date=May 4, 2009 }}, Newfoundland and Labrador Heritage, Memorial University of Newfoundland. Retrieved January 26, 2010</ref><ref>{{cite journal|doi=10.2307/277719|author=Tuck|first1= James A.|year=1971 |title=An Archaic Cemetery at Port Au Choix, Newfoundland|journal=American Antiquity|volume=36|issue=3|pages=343–358|jstor=277719|s2cid=163391715 }}</ref>

In the tales and beliefs of the Siberian Yupik people, orcas are said to appear as [[Biology:Wolf|wolves]] in winter, and wolves as orcas in summer.<ref name=rubow>''The orphan boy with his sister'', p. 156 in Rubcova, E. S. (1954). ''Materials on the Language and Folklore of the Eskimoes, Vol. I, Chaplino Dialect''. Leningrad: Academy of Sciences of the USSR. Original data: Е.С. Рубцова: Материалы по языку и фольклору эскимосов (чаплинский диалект). Академия Наук СССР. Москва-Ленинград, 1954</ref><ref name=menow>Menovshchikov, G. A. (1962). ''Grammar of the language of Asian Eskimos''. Vol. I., pp. 439, 441. Moscow and Leningrad: Academy of Sciences of the USSR. Original data: Г. А. Меновщиков: Грамматиκа языка азиатских эскимосов. Часть первая. Академия Наук СССР. Москва-Ленинград, 1962</ref><ref name=ssipr>{{cite web|url=http://www.nsu.ru/ip/eskimos.php#3|title=Поддержка прав коренных народов Cибири - Spiritual culture subsection of the Eskimos page in the Support for Siberian Indigenous Peoples Rights|work=nsu.ru|language=ru|url-status=dead|archive-url=https://web.archive.org/web/20070830162420/http://www.nsu.ru/ip/eskimos.php#3|archive-date=August 30, 2007}}</ref><ref name=submit>{{cite web |last=Vajda |first=Edward J |title=Siberian Yupik (Eskimo) |work=East Asian Studies |url=http://pandora.cii.wwu.edu/vajda/ea210/aleut.htm |access-date=August 7, 2013 |archive-url=https://web.archive.org/web/20161028052901/http://pandora.cii.wwu.edu/vajda/ea210/aleut.htm |archive-date=October 28, 2016 |url-status=dead }}</ref> Orcas are believed to assist their hunters in driving walrus.<ref name=radio>{{cite serial |credits=Ковалева, Ирина & Богословская, Людмила |script-title=ru:Животные и отражение их прихода к человеку в самых разных текстах |network=Эхо Москвы |station=Арсенал |airdate=December 3, 2002 |url=http://echo.msk.ru/programs/beseda/20523/ |language=ru |access-date=April 29, 2008 |archive-date=May 5, 2008 |archive-url=https://web.archive.org/web/20080505005651/http://echo.msk.ru/programs/beseda/20523/ |url-status=live }} A radio interview with Russian scientists about man and animal, examples taken especially from Asian Eskimos</ref> Reverence is expressed in several forms: the boat represents the animal, and a wooden carving hung from the hunter's belt.<ref name=ssipr/> Small sacrifices such as tobacco or meat are strewn into the sea for them.<ref name=radio/><ref name=submit/>

The Ainu people of Hokkaido, the Kuril Islands, and southern Sakhalin often referred to orcas in their folklore and myth as ''Repun Kamuy'' (God of Sea/Offshore) to bring fortunes (whales) to the coasts, and there had been traditional funerals for stranded or deceased orcas akin to funerals for other animals such as [[Biology:Brown bear|brown bear]]s.<ref>{{cite news |last=Miyanaga |first=T. |year=2014 |script-title=ja:（北海道）「シャチ送り」の遺構か 礼文島の遺跡で出土 |newspaper=Asahi Shimbun |language=ja}}</ref>

==="Killer" stereotype===
[[File:Whale of Greifswald from rear.JPG|right|thumb|Male orca depicted in St Mary's in Greifswald, Germany, 1545<ref name="Greifswald church"/>|alt=Killer whale silhouette, with two projections above shown above the blowhole.]]
In [[Social:Western culture|Western culture]]s, orcas were historically feared as dangerous, savage predators.{{sfn|Obee|Ellis|1992|pp=Chapter 1}} The first written description of an orca was given by Pliny the Elder ''circa'' AD 70, who wrote, "Orcas (the appearance of which no image can express, other than an enormous mass of savage flesh with teeth) are the enemy of [other kinds of whale]... they charge and pierce them like warships ramming." (see citation in section "Naming", above).<ref name=pliny1>Gaius Plinius Secundus. [https://penelope.uchicago.edu/Thayer/L/Roman/Texts/Pliny_the_Elder/9*.html#v ''Historia Naturalis'' 9.5.12] {{Webarchive|url=https://web.archive.org/web/20200915041547/http://penelope.uchicago.edu/Thayer/L/Roman/Texts/Pliny_the_Elder/9%2A.html#v |date=September 15, 2020 }} (Latin), in Bill Thayer's ''[https://penelope.uchicago.edu/Thayer/E/Roman/home.html LacusCurtius: Into the Roman World] {{Webarchive|url=https://archive.today/20120524002003/http://penelope.uchicago.edu/Thayer/E/Roman/home.html |date=May 24, 2012 }}''. (See also an [https://www.perseus.tufts.edu/hopper/text?doc=Perseus:text:1999.02.0137:book=9:chapter=5 English translation] {{Webarchive|url=https://web.archive.org/web/20110604093248/http://www.perseus.tufts.edu/hopper/text?doc=Perseus:text:1999.02.0137:book=9:chapter=5 |date=June 4, 2011 }} by John Bostock and Henry Thomas Riley, 1855.) Retrieved February 19, 2010.</ref>

Of the very few confirmed attacks on humans by wild orcas, none have been fatal.<ref name="3_News_71245">{{cite news |url=http://www.3news.co.nz/Orca-shares-the-waves-with-local-surfer/tabid/423/articleID/71245/Default.aspx |title=Orca shares the waves with local surfer |date=September 12, 2008 |work=3 News |access-date=October 13, 2011 |archive-url=https://web.archive.org/web/20110724192551/http://www.3news.co.nz/Orca-shares-the-waves-with-local-surfer/tabid/423/articleID/71245/Default.aspx |archive-date=July 24, 2011 |url-status=dead }}</ref> In one instance, orcas tried to tip ice floes on which a dog team and photographer of the Terra Nova Expedition were standing.<ref>{{Cite book|last=Cherry-Garrard|first=Apsley|title=The Worst Journey in the World: Antarctic 1910–1913|publisher=Globe Pequot|year=2004|page=92|isbn=978-1-59228-212-8}}</ref> The sled dogs' barking is speculated to have sounded enough like seal calls to trigger the orca's hunting curiosity. In the 1970s, a surfer in California was bitten, and in 2005, a boy in Alaska who was splashing in a region frequented by harbour seals was bumped by an orca that apparently misidentified him as prey.<ref name=ketchikan>{{cite news |agency=The Associated Press |url=https://www.seattletimes.com/seattle-news/boy-survives-bump-from-killer-whale |title=Boy survives bump from killer whale |newspaper=The Seattle Times |date=August 18, 2005 |access-date=January 3, 2010 |archive-date=April 2, 2011 |archive-url=https://web.archive.org/web/20110402062946/http://seattletimes.nwsource.com/html/localnews/2002444869_webwhale18.html |url-status=live }}</ref> Unlike wild orcas, captive orcas have made nearly two dozen attacks on humans since the 1970s, some of which have been fatal.<ref name=abc2006>{{cite web |url=https://abcnews.go.com/GMA/story?id=2690153 |title=ABC News: Killer Whale Attacks SeaWorld Trainer |publisher=ABC News |date=November 30, 2006 |access-date=January 3, 2010 |archive-date=February 28, 2010 |archive-url=https://web.archive.org/web/20100228172014/http://abcnews.go.com/GMA/story?id=2690153 |url-status=live }}</ref><ref>"[http://edition.cnn.com/2010/US/02/24/killer.whale.trainer.death/index.html SeaWorld trainer killed by killer whale]" {{Webarchive|url=https://web.archive.org/web/20100403195245/http://edition.cnn.com/2010/US/02/24/killer.whale.trainer.death/index.html |date=April 3, 2010}}, CNN, February 25, 2010, Retrieved September 9, 2010</ref>

Competition with fishermen also led to orcas being regarded as pests. In the waters of the [[Place:Pacific Northwest|Pacific Northwest]] and Iceland, the shooting of orcas was accepted and even encouraged by governments.{{sfn|Obee|Ellis|1992|pp=Chapter 1}} As an indication of the intensity of shooting that occurred until fairly recently, about 25% of the orcas captured in Puget Sound for aquariums through 1970 bore bullet scars.{{sfn|NMFS|2005|p=41}} The U.S. Navy claimed to have deliberately killed hundreds of orcas in Icelandic waters in 1956 with machine guns, rockets, and depth charges.<ref>Killer Whales Destroyed: VP-7 Accomplishes Special Task, ''Naval Aviation News'', December 1956, p. 19. Reproduced at [http://www.seaworld.org/infobooks/KillerWhale/deathkw.html Longevity and Causes of Death] {{Webarchive|url=https://web.archive.org/web/20100619230958/http://seaworld.org/infobooks/KillerWhale/deathkw.html |date=June 19, 2010 }}, SeaWorld/Busch Gardens ANIMALS. Retrieved January 11, 2010</ref><ref>{{cite journal |title=Naval War Declared Against Killer Whales|journal=The Science News-Letter|volume=69|issue=24|page=374|year=1956|jstor=3936619 |doi=10.2307/3936617}}</ref>

===Modern Western attitudes===
[[File:Woman swims with killer whales in the wild.webm|thumb|Ingrid Visser's research team filming orcas in New Zealand]]

Western attitudes towards orcas have changed dramatically in recent decades. In the mid-1960s and early 1970s, orcas came to much greater public and scientific awareness, starting with the live-capture and display of an orca known as Moby Doll, a southern resident orca harpooned off Saturna Island in 1964.{{sfn|Obee|Ellis|1992|pp=Chapter 1}} He was the first ever orca to be studied at close quarters alive, not postmortem. [[Biology:Moby Doll's impact in scientific research|Moby Doll's impact in scientific research]] at the time, including the first scientific studies of an orca's sound production, led to two articles about him in the journal ''Zoologica''.<ref name=Schevill&Watkins>{{cite journal |last1=Schevill |first1=William |last2=Watkins |first2=William |title=Sound Structure and Directionality in ''Orcinus'' (killer whale) |journal=Zoologica |date=Summer 1966 |volume=51 |issue=2 |pages=71–76 |publisher=New York Zoological Society}}</ref><ref name=Newman&McGeer>{{cite journal |last1=Newman |first1=Murray |last2=McGeer |first2=Patrick |title=The Capture and Care of a Killer Whale, ''Orcinus orca'', in British Columbia |journal=Zoologica |date=Summer 1966 |volume=51 |issue=2 |pages=59–70 |publisher=New York Zoological Society}}</ref> So little was known at the time, it was nearly two months before the whale's keepers discovered what food (fish) it was willing to eat. To the surprise of those who saw him, Moby Doll was a docile, non-aggressive whale who made no attempts to attack humans.{{sfn|Francis|Hewlett|2007|pp=58–59}}

[[File:A73 whale transport.jpg|thumb|right|upright|In 2002, the orphan Springer was successfully returned to her family.|alt=Killer whale wrapped in white cloth on a boat, surrounded by four people. A board braces its dorsal fin.]]
Between 1964 and 1976, 50 orcas from the Pacific Northwest were captured for display in aquaria, and public interest in the animals grew. In the 1970s, research pioneered by Michael Bigg led to the discovery of the species' complex social structure, its use of vocal communication, and its extraordinarily stable mother–offspring bonds. Through [[Wildlife photo-identification|photo-identification]] techniques, individuals were named and tracked over decades.{{sfn|Baird|2002|pp=73–80}}

Bigg's techniques also revealed the Pacific Northwest population was in the low hundreds rather than the thousands that had been previously assumed.{{sfn|Obee|Ellis|1992|pp=Chapter 1}} The southern resident community alone had lost 48 of its members to captivity; by 1976, only 80 remained.{{sfn|Heimlich|Boran|2001|p=11}} In the Pacific Northwest, the species that had unthinkingly been targeted became a cultural icon within a few decades.<ref name=Lyke/>

The public's growing appreciation also led to growing opposition to whale–keeping in aquarium. Only one whale has been taken in North American waters since 1976. In recent years, the extent of the public's interest in orcas has manifested itself in several high-profile efforts surrounding individuals. Following the success of the 1993 film ''Free Willy'', the movie's captive star Keiko was returned to the coast of his native Iceland in 2002. The director of the International Marine Mammal Project for the Earth Island Institute, David Phillips, led the efforts to return Keiko to the Iceland waters.<ref name = Wood>{{cite news|last=Wood|first=Daniel|title=Death of Sea World trainer: Do 'killer whales' belong in theme parks?|url=http://www.csmonitor.com/USA/2010/0224/Death-of-Sea-World-trainer-Do-killer-whales-belong-in-theme-parks|access-date=March 19, 2012|newspaper=The Christian Science Monitor|date=February 24, 2010|archive-date=May 13, 2012|archive-url=https://web.archive.org/web/20120513095029/http://www.csmonitor.com/USA/2010/0224/Death-of-Sea-World-trainer-Do-killer-whales-belong-in-theme-parks|url-status=live}}</ref> Keiko however did not adapt to the harsh climate of the [[Earth:Arctic Ocean|Arctic Ocean]], and died a year into his release after contracting [[Biology:Pneumonia (non-human)|pneumonia]], at the age of 27.<ref>[https://apnews.com/f4012a2567261d6a6e661c1c636c128b Movie-Star Whale Keiko Dies of Pneumonia.] {{Webarchive|url=https://web.archive.org/web/20200607115808/https://apnews.com/f4012a2567261d6a6e661c1c636c128b |date=June 7, 2020 }} Associated Press. Published December 13, 2003. Retrieved June 7, 2020.</ref> In 2002, the orphan Springer was discovered in Puget Sound, Washington. She became the first whale to be successfully reintegrated into a wild pod after human intervention, crystallizing decades of research into the vocal behaviour and social structure of the region's orcas.<ref name=autogenerated2>{{Cite news|title=Orphaned orca's reunion with family celebrated|url=https://www.cbc.ca/news/canada/british-columbia/orphaned-orca-s-reunion-with-family-celebrated-1.634335|date=July 13, 2007|publisher=Canadian Broadcasting Corporation|access-date=November 6, 2007|archive-date=November 6, 2015|archive-url=https://web.archive.org/web/20151106234637/http://www.cbc.ca/news/canada/british-columbia/orphaned-orca-s-reunion-with-family-celebrated-1.634335|url-status=live}}</ref> The saving of Springer raised hopes that another young orca named Luna, which had become separated from his pod, could be returned to it. However, his case was marked by controversy about whether and how to intervene, and in 2006, Luna was killed by a boat propeller.<ref>{{Cite news |first=Robert |last=McClure |title=Luna the orca killed by tugboat |url=http://www.seattlepi.com/local/article/Luna-the-orca-killed-by-tugboat-1198168.php |work=Seattle Post-Intelligencer |publisher=Hearst Corporation |location=Seattle, Washington |date=March 11, 2006 |access-date=April 8, 2009 |archive-date=August 11, 2011 |archive-url=https://web.archive.org/web/20110811030505/http://www.seattlepi.com/local/article/Luna-the-orca-killed-by-tugboat-1198168.php |url-status=live }}</ref>

===Whaling===
[[File:Killer Whale (Old Tom) and whalers.jpeg|thumb|upright=1.2|The orca named Old Tom swims alongside a whaleboat, flanking a whale calf. The boat is being towed by a harpooned whale (not visible here), near Eden, Australia.|alt=A killer whale swims alongside a whaling boat, with a smaller whale in between. Two men are standing, the harpooner in the bow and a steersman on the aft rudder, while four oarsmen are seated.]]

The earlier of known records of commercial hunting of orcas date to the 18th century in Japan. During the 19th and early 20th centuries, the global whaling industry caught immense numbers of [[Biology:Baleen whale|baleen]] and sperm whales, but largely ignored orcas because of their limited amounts of [[Earth:Whale oil|recoverable oil]], their smaller populations, and the difficulty of taking them.{{sfn|NMFS|2005|p=39}} Once the stocks of larger species were depleted, orcas were targeted by commercial whalers in the mid-20th century. Between 1954 and 1997, Japan took 1,178 orcas (although the Ministry of the Environment claims that there had been domestic catches of about 1,600 whales between late 1940s to 1960s<ref>{{cite journal|year=1998|title=海域自然環境保全基礎調査 - 海棲動物調査報告書, (2)- 19. シャチ ''Orcinus orca'' (Limaeus,1758)マイルカ科|url=http://www.biodic.go.jp/reports2/5th/kaisei_h10/5_kaisei_h10.pdf|page=54|journal=自然環境保全基礎調査|access-date=January 14, 2015|archive-date=July 17, 2015|archive-url=https://web.archive.org/web/20150717041428/http://www.biodic.go.jp/reports2/5th/kaisei_h10/5_kaisei_h10.pdf|url-status=live}}</ref>) and Norway took 987.{{sfn|Obee|Ellis|1992|p=34}} Extensive hunting of orcas, including an Antarctic catch of 916 in 1979–80 alone, prompted the International Whaling Commission to recommend a ban on commercial hunting of the species pending further research.{{sfn|Obee|Ellis|1992|p=34}} Today, no country carries out a substantial hunt, although Indonesia and [[Place:Greenland|Greenland]] permit small subsistence hunts (see Aboriginal whaling). Other than commercial hunts, orcas were hunted along Japanese coasts out of public concern for potential conflicts with fisheries. Such cases include a semi-resident male-female pair in Akashi Strait and Harimanada being killed in the Seto Inland Sea in 1957,<ref name=OSAKACEA>{{cite web|publisher=Osaka College of Eco & Animals|year=2011|script-title=ja:シャチ騒動|url=http://cblog-eco.oca.ac.jp/blog/2011/10/post-aa1b.html|access-date=December 24, 2014|language=ja|archive-date=December 24, 2014|archive-url=https://web.archive.org/web/20141224113540/http://cblog-eco.oca.ac.jp/blog/2011/10/post-aa1b.html|url-status=live}}</ref><ref>{{cite web|publisher=The Whale Laboratory of Shimonoseki|year=2014|title=Stranding Base (1901–2012) for Hyogo Prefecture|url=http://whalelab.org/HyogoPRF.htm|access-date=December 24, 2014|archive-date=December 24, 2014|archive-url=https://web.archive.org/web/20141224112918/http://whalelab.org/HyogoPRF.htm|url-status=live}}</ref> the killing of five whales from a pod of 11 members that swam into Tokyo Bay in 1970,<ref>{{cite web|publisher=The Whale Laboratory of Shimonoseki|year=2014|title=Stranding Date Base (1901-2012) for Chiba Prefecture|url=http://whalelab.org/ChibaPRF.htm|access-date=January 9, 2015|archive-date=January 9, 2015|archive-url=https://web.archive.org/web/20150109080045/http://whalelab.org/ChibaPRF.htm|url-status=live}}</ref> and a catch record in southern Taiwan in the 1990s.<ref name=SmallCetaceansChina>{{cite journal|author=Kaiya|first1= Z.|last2=Leatherwood|first2= S.|last3=Jefferson |first3=A. T.|title=Records of Small Cetaceans in Chinese Waters: A Review|journal=Asian Marine Biology|volume=12|year=1995|pages=119–139|url=https://swfsc.noaa.gov/uploadedFiles/Divisions/PRD/Publications/Zhouetal95(26).pdf|access-date=December 24, 2014|archive-date=July 17, 2015|archive-url=https://web.archive.org/web/20150717073608/https://swfsc.noaa.gov/uploadedFiles/Divisions/PRD/Publications/Zhouetal95(26).pdf|url-status=live}}</ref><ref>{{cite journal|author=Kaiya|first1= Z.|last2=Leatherwood |first2=S.|last3=Jefferson|first3= A. T. |year=2002 |title=Report of the Second Workshop on The Biology and Conservation of Small Cetaceans and Dugongs of South-East Asia |journal=CMS Technical Series Publication Nº 9 at Convention on Migratory Species |url=http://www.iucn-csg.org/wp-content/uploads/2010/03/Perrinetal.0589.pdf |editor=Perrin F. W. |editor2=Reeves R. R. |editor3=Dolar L. L. M. |editor4=Jefferson A. T. |editor5=Marsh H. |editor6=Wang Y. J. |editor7=Estacion J. |access-date=December 24, 2014 |url-status=dead |archive-url=https://web.archive.org/web/20160304045901/http://www.iucn-csg.org/wp-content/uploads/2010/03/Perrinetal.0589.pdf |archive-date=March 4, 2016 }}</ref>

====Cooperation with humans====
Orcas have helped humans hunting other whales.<ref name="scavenging">{{cite journal|last1=Reeves|first1=Randall|last2=Whitehead|first2=Hal|title=Killer whales and whaling: the scavenging hypothesis|journal=Biology Letters|volume=1|issue=4|pages=415–418|year=2005|pmid=17148221|pmc=1626385|doi=10.1098/rsbl.2005.0348}}</ref> One well-known example was the orcas of Eden, Australia, including the male known as Old Tom. Whalers more often considered them a nuisance, however, as orcas would gather to scavenge meat from the whalers' catch.<ref name="scavenging"/> Some populations, such as in Alaska's Prince William Sound, may have been reduced significantly by whalers shooting them in retaliation.<ref name=baird/>

===Whale watching===
Whale watching continues to increase in popularity, but may have some problematic impacts on orcas. Exposure to exhaust gases from large amounts of vessel traffic is causing concern for the overall health of the 75 remaining southern resident orcas (SRKWs) left as of early 2019.<ref>{{Cite web|url=https://www.bewhalewise.org/|title=Home|website=Be Whale Wise|access-date=October 31, 2019|archive-date=October 31, 2019|archive-url=https://web.archive.org/web/20191031050019/https://www.bewhalewise.org/|url-status=live}}</ref> This population is followed by approximately 20 vessels for 12 hours a day during the months May–September.<ref name="Lachmuth et al. 2011">{{cite journal |last1=Lachmuth |first1=Cara L. |last2=Barrett-Lennard |first2=Lance G. |last3=Steyn |first3=D. Q. |last4=Milsom |first4=William K. |title=Estimation of southern resident killer whale exposure to exhaust emissions from whale-watching vessels and potential adverse health effects and toxicity thresholds |journal=Marine Pollution Bulletin |date=April 2011 |volume=62 |issue=4 |pages=792–805 |doi=10.1016/j.marpolbul.2011.01.002 |pmid=21276987|bibcode=2011MarPB..62..792L }}</ref> Researchers discovered that these vessels are in the line of sight for these whales for 98–99.5% of daylight hours.<ref name="Lachmuth et al. 2011"/> With so many vessels, the air quality around these whales deteriorates and impacts their health. Air pollutants that bind with exhaust fumes are responsible for the activation of the cytochrome P450 1A gene family.<ref name="Lachmuth et al. 2011"/> Researchers have successfully identified this gene in skin biopsies of live whales and also the lungs of deceased whales. A direct correlation between activation of this gene and the air pollutants can not be made because there are other known factors that will induce the same gene. Vessels can have either wet or dry exhaust systems, with wet exhaust systems leaving more pollutants in the water due to various gas solubility. A modelling study determined that the lowest-observed-adverse-effect-level (LOAEL) of exhaust pollutants was about 12% of the human dose.<ref name="Lachmuth et al. 2011"/>

As a response to this, in 2017 boats off the British Columbia coast now have a minimum approach distance of 200 metres compared to the previous 100 metres. This new rule complements Washington State's minimum approach zone of 180 metres that has been in effect since 2011. If a whale approaches a vessel it must be placed in neutral until the whale passes. The World Health Organization has set air quality standards in an effort to control the emissions produced by these vessels.<ref>{{Cite web|url = https://baleinesendirect.org/en/boats-to-maintain-greater-distance-from-killer-whales/|title = Boats to Maintain Greater Distance from Killer Whales &#124; Whales online|date = November 8, 2017|access-date = March 14, 2019|archive-date = March 30, 2019|archive-url = https://web.archive.org/web/20190330230118/https://baleinesendirect.org/en/boats-to-maintain-greater-distance-from-killer-whales/|url-status = live}}</ref>

===Captivity===
[[File:Miami Oceanarium.jpg|thumb|Lolita, at the Miami Seaquarium, was one of the oldest orcas in captivity.]]
The orca's intelligence, trainability, striking appearance, playfulness in captivity and sheer size have made it a popular exhibit at aquaria and aquatic theme parks. From 1976 to 1997, 55 whales were taken from the wild in Iceland, 19 from Japan, and three from Argentina. These figures exclude animals that died during capture. Live captures fell dramatically in the 1990s, and by 1999, about 40% of the 48 animals on display in the world were captive-born.{{sfn|NMFS|2005|pp=43–44}}

Organizations such as World Animal Protection and the [[Organization:Whale and Dolphin Conservation|Whale and Dolphin Conservation]] campaign against the practice of keeping them in captivity. In captivity, they often develop pathologies, such as the dorsal fin collapse seen in 60–90% of captive males. Captives have vastly reduced life expectancies, on average only living into their 20s.{{efn|Although there are examples of killer whales living longer, including several over 30 years old, and two captive orcas (Corky II and Lolita) are in their mid-40s.}} That said, a 2015 study coauthored by staff at SeaWorld and the Minnesota Zoo suggested no significant difference in survivorship between free-ranging and captive orcas.<ref name=robeck/> However, in the wild, females who survive infancy live 46 years on average, and up to 70–80 years in rare cases. Wild males who survive infancy live 31 years on average, and up to 50–60 years.<ref>{{cite web|author=Rose|first1= N. A.|year=2011|url=http://www.hsi.org/assets/pdfs/orca_white_paper.pdf|title=Killer Controversy: Why Orcas Should No Longer Be Kept in Captivity|publisher=Humane Society International and the Humane Society of the United States|access-date=December 21, 2014|archive-date=December 30, 2017|archive-url=https://web.archive.org/web/20171230032203/http://www.hsi.org/assets/pdfs/orca_white_paper.pdf|url-status=live}}</ref> Captivity usually bears little resemblance to wild habitat, and captive whales' social groups are foreign to those found in the wild. Critics claim captive life is stressful due to these factors and the requirement to perform circus tricks that are not part of wild orca behaviour, see above.<ref>{{cite web|url=http://www.wdcs.org/submissions_bin/cap-orc-glo-000016.pdf |title=Orcas in captivity |publisher=Whale and Dolphin Conservation Society |access-date=January 26, 2010 |url-status=dead |archive-url=https://web.archive.org/web/20100706134353/http://www.wdcs.org/submissions_bin/cap-orc-glo-000016.pdf |archive-date=July 6, 2010 }}</ref> Wild orcas may travel up to {{convert|160|km|mi|-1}} in a day, and critics say the animals are too big and intelligent to be suitable for captivity.<ref name=cbs2010>Associated Press. [http://www.cbsnews.com/stories/2010/03/01/national/main6255297.shtml Whale Attack Renews Captive Animal Debate] {{Webarchive|url=https://web.archive.org/web/20100305103754/http://www.cbsnews.com/stories/2010/03/01/national/main6255297.shtml |date=March 5, 2010 }} ''CBS News'', March 1, 2010. Retrieved March 7, 2010</ref> Captives occasionally act aggressively towards themselves, their tankmates, or humans, which critics say is a result of stress.<ref name=abc2006 /> Between 1991 and 2010, the bull orca known as Tilikum was involved in the death of three people, and was featured in the critically acclaimed 2013 film ''Blackfish''.<ref name="RT review 1">{{cite web|url=http://www.rottentomatoes.com/m/blackfish_2013|title=Blackfish|website=Rotten Tomatoes|access-date=November 23, 2013|archive-date=November 21, 2013|archive-url=https://web.archive.org/web/20131121215751/http://www.rottentomatoes.com/m/blackfish_2013/|url-status=live}}</ref> Tilikum lived at SeaWorld from 1992 until his death in 2017.<ref>{{cite book|chapter=The Killer in the Pool|first=Tim|last=Zimmerman|title=The Best American Sampler 2011|page=336|publisher=Houghton Mifflin Harcourt|year=2011}}</ref><ref>{{cite news|url=https://www.nytimes.com/1999/07/07/us/corpse-is-found-on-whale.html|title=Corpse Is Found on Whale|newspaper={{wipe|The New York Times}}|date=July 7, 1999|access-date=September 11, 2011|archive-date=June 13, 2012|archive-url=https://web.archive.org/web/20120613184958/http://www.nytimes.com/1999/07/07/us/corpse-is-found-on-whale.html|url-status=live}}</ref>

In March 2016, SeaWorld announced that they would be ending their orca breeding program and their theatrical shows.<ref>{{Cite web|url=http://news.nationalgeographic.com/2016/03/160317-seaworld-orcas-killer-whales-captivity-breeding-shamu-tilikum/|title=SeaWorld to End Controversial Orca Shows and Breeding|date=March 17, 2016|website=National Geographic News|access-date=September 27, 2016|archive-date=April 20, 2016|archive-url=https://web.archive.org/web/20160420052351/http://news.nationalgeographic.com/2016/03/160317-seaworld-orcas-killer-whales-captivity-breeding-shamu-tilikum/|url-status=dead}}</ref> However, as of 2020, theatrical shows featuring orcas are still ongoing.<ref>{{Cite web|last=Stevens|first=Blair|date=2020-06-11|title=Even years after Blackfish, SeaWorld still has Orcas|url=https://8forty.ca/2020/06/10/even-years-after-blackfish-seaworld-still-has-orcas/|access-date=2020-12-23|language=en}}</ref>

=== Orca attacks on sailboats and small vessels ===
Beginning around 2020 one or more pods of orcas began to attack sailing vessels off the Southern tip of Europe and a few were sunk. At least 15 interactions between orcas and boats off the Iberian coast were reported in 2020.<ref>{{Cite web |date=2023-05-23 |title=Scientists are puzzled by Orcas sinking boats in a string of abnormal attacks |url=https://www.nbcnews.com/science/science-news/orcas-sank-three-boats-coast-portugal-dont-call-killer-just-yet-rcna85678 |access-date=2023-07-04 |website=NBC News |language=en}}</ref> According to the Atlantic Orca Working Group (GTOA) as many as 500 vessels have been damaged between 2020 and 2023.<ref>{{Cite web |date=2023-05-29 |title=Gladis the killer whale and her gang of orcas out for revenge |url=https://www.independent.co.uk/news/world/europe/gladis-whale-orca-boat-attacks-gibraltar-b2347572.html |access-date=2023-07-05 |website=The Independent |language=en}}</ref> In one  video, an orca can be seen biting on one of the two rudders ripped from a catamaran near [[Place:Gibraltar|Gibraltar]]. The captain of the vessel reported this was the second attack on a vessel under his command and the orcas focused on the rudders. "Looks like they knew exactly what they are doing. They didn't touch anything else."<ref>{{Cite web |last=Dewan |first=Pandora |date=2023-06-09 |title=Orcas filmed destroying ship's rudder in shocking clip: "Surrounded" |url=https://www.newsweek.com/orcas-filmed-destroying-ship-rudder-shocking-clip-surrounded-1805644 |access-date=2023-07-05 |website=Newsweek |language=en}}</ref> After an orca repeatedly rammed a vessel off the coast of Norway in 2023, there is a concern the behavior is spreading to other areas.<ref>{{Cite news |last1=Hoare |first1=Philip |last2=Hoekendijk |first2=Jeroen |date=2023-06-21 |title=Orca rams into yacht off Shetland in first such incident in northern waters |language=en-GB |work=The Guardian |url=https://www.theguardian.com/environment/2023/jun/21/orca-rams-yacht-off-shetland-first-such-incident-northern-waters |access-date=2023-07-04 |issn=0261-3077}}</ref> This has led to recommendations that sailors now carry bags of sand.<ref>{{Cite web |date=2023-06-19 |title=Sprinkling sand 'deters orcas' according to Cruising Association |url=https://www.pbo.co.uk/news/orca-sand-deterrence-77513 |access-date=2023-07-04 |website=Practical Boat Owner |language=en-US}}</ref> Dropping sand into the water near the rudder is thought to confuse the sonar signal.<ref>{{Cite news |last=Crisp |first=James |date=2023-05-27 |title=Sailors have a new way to stop killer whale attacks |language=en-GB |work=The Telegraph |url=https://www.telegraph.co.uk/world-news/2023/05/27/orcas-killer-whales-attacking-boats-strait-gibraltar-sand/ |access-date=2023-07-04 |issn=0307-1235}}</ref>

==See also==
*List of marine mammal species
**List of cetaceans
***''[[Biology:Livyatan|Livyatan]] melvillei'' – occupied a similar ecological niche
*Ingrid Visser (researcher) – a New Zealand biologist who swims with wild orcas

==Footnotes==
{{notelist}}
{{Reflist|group=Note}}

==References==
{{reflist}}

===Works cited===
*{{Cite book |last=Baird |first=Robin W. |title=Killer Whales of the World |publisher=Voyageur Press |location=Stillwater, MN. |url=https://books.google.com/books?id=Rjksm-5-ap4C&pg=PP1 |year=2002 |isbn=978-0-7603-2654-1}}
*{{Cite book |last=Carwardine |first=Mark |year=2001 |title=Killer Whales |location=London |publisher=BBC Worldwide |isbn=978-0-7894-8266-2|url=https://archive.org/details/killerwhales00carw}}
*{{Cite encyclopedia |last=Ford |first=John K. B. |year=2002 |chapter=Killer Whale |pages=[https://archive.org/details/encyclopediaofma2002unse/page/669 669–675] |chapter-url=https://books.google.com/books?id=2rkHQpToi9sC&pg=PP1 |encyclopedia=Encyclopedia of Marine Mammals |publisher=[[Company:Academic Press|Academic Press]] |isbn=0-12-551340-2 |url=https://archive.org/details/encyclopediaofma2002unse/page/669 }}
*{{Cite book|last1=Ford |first1=John K. B. |last2=Ellis |first2=Graeme M. |last3=Balcomb |first3=Kenneth C. |title=Killer Whales |edition=Second|year=2000|publisher=UBC Press|location=Vancouver, BC|isbn=978-0-7748-0800-2|url=https://books.google.com/books?id=yTmbu_CFomAC&pg=PP1}}
*{{Cite journal |last1=Ford |first1=John K. B. |last2=Ellis |first2=Graeme M. |year=2006 |pages=185–199 |title=Selective foraging by fish-eating killer whales ''Orcinus orca'' in British Columbia |journal=Marine Ecology Progress Series |volume=316 |doi=10.3354/meps316185 |bibcode=2006MEPS..316..185F|doi-access=free }}
*{{Cite book |last1=Francis |first1=Daniel |first2=Gil |last2=Hewlett |title=Operation Orca: Springer, Luna and the Struggle to Save West Coast Killer Whales |year=2007 |publisher=Harbour Publishing |location=Madeira Park, B.C. |isbn=978-1-55017-426-7}}
*{{Cite book |last1=Heptner |first1=V. G. |last2=Nasimovich |first2=A. A. |last3=Bannikov |first3=A. G. |last4=Hoffmann |first4=Robert S. |url=https://archive.org/details/mammalsofsov231996gept |title=Mammals of the Soviet Union |volume=II, part 3 |year=1996 |publisher=Smithsonian Institution Libraries and National Science Foundation |location=Washington D.C. |isbn=978-1-886106-81-9}}
*{{cite web |publisher=National Marine Fisheries Service (NMFS) Northwest Regional Office |author=NMFS |year=2005 |url=http://www.nwr.noaa.gov/Marine-Mammals/Whales-Dolphins-Porpoise/Killer-Whales/Conservation-Planning/upload/SRKW-propConsPlan.pdf |title=Conservation Plan for Southern Resident Killer Whales (''Orcinus orca'') |location=Seattle, U.S. |access-date=January 2, 2009 |archive-url=https://web.archive.org/web/20080626121719/http://www.nwr.noaa.gov/Marine-Mammals/Whales-Dolphins-Porpoise/Killer-Whales/Conservation-Planning/upload/SRKW-propConsPlan.pdf |archive-date=June 26, 2008 |url-status=dead}}
*{{Cite book |isbn=978-1-55110-034-0 |last1=Obee |first1=Bruce |first2=Graeme |last2=Ellis |title=Guardians of the Whales: The Quest to Study Whales in the Wild |editor=Elaine Jones |publisher=Whitecap Books |location=North Vancouver, British Columbia |year=1992}}

==Further reading==
*{{cite magazine|title=The Whales Called "Killer"|magazine=National Geographic|first=Erich|last=Hoyt|pages=220–237|volume=166|issue=2|date=August 1984|issn=0027-9358|oclc=643483454}}
*{{citation |last=Hoyt |first=Erich |year=1998 |title=Orca: The Whale Called Killer Camden House Publishing |isbn=978-0-920656-25-9 |url-access=registration |url=https://archive.org/details/orca00eric_0 }}
*{{Cite book |title=Behavioral Biology of Killer Whales |first1=B. C. |last1=Kirkevold |first2=J. S.|last2= Lockard |publisher=Alan R. Liss Inc. |year=1986 |isbn=978-0-8451-3100-8}}

==External links==
{{EB1911 poster|Grampus}}
{{Commons|Orcinus orca}}
* [http://www.orca-live.net/ Orca-Live]&nbsp;– Orcas in Johnstone Strait, British Columbia
* [http://orcasound.net/ Salish Sea Hydrophone Network]&nbsp;– Listen live to orcas in Washington State, U.S.
* [https://web.archive.org/web/20101216065407/http://www.keepwhaleswild.org/ Keep Whales Wild]
* [https://animals.howstuffworks.com/mammals/orca-killer-whale.htm Why are orca called killer whales?], HowStuffWorks.com, article by Jacob Silverman
* [https://web.archive.org/web/20140709235820/http://cetus.ucsd.edu/voicesinthesea_org/species/dolphins/orca.html Voices in the Sea - Sounds of the Orca (Killer Whale)]
* [http://www.gadling.com/2011/03/27/killer-whale-devours-great-white-shark/ Orca devours great white shark]
* [https://www.youtube.com/watch?time_continue=1&v=IZTSd-CMEno&feature=emb_title Orcas Preying On Dolphins (Caught On Drone)], off the coast of San Clemente
* [https://www.youtube.com/watch?v=sRFp3kEBV-A Orcas vs Sperm Whales]
* [https://www.youtube.com/watch?v=8KCQrLA3UKw Watch: Killer Whales Charge Blue Whale (Rare Drone Footage)] | National Geographic

{{Cetacea|O.}}

{{Taxonbar |from=Q26843}}

[[Category:Cosmopolitan mammals]]
[[Category:Oceanic dolphins]]
[[Category:Animals that use echolocation]]

{{Sourceattribution|Orca}}