View source for Narwhal

{{Short description|Medium-sized toothed whale species}}
{{Other uses}}
{{pp-vandalism|small=yes}}
{{Good article}}
{{Use British English|date=May 2024}}
{{Use dmy dates|date=August 2024}} 
{{Speciesbox
| name = Narwhal
| fossil_range = {{fossil range|Quaternary|Present}}<ref>{{Cite book |last=Newton |first=Edwin Tulley |title=The Vertebrata of the Pliocene deposits of Britain |date=1891 |publisher=Her Majesty's Stationery Office |location=London |doi=10.5962/bhl.title.57425 |hdl=2027/mdp.39015066912331 }}</ref><ref>{{Cite web |title=Monodon monoceros Linnaeus 1758 (narhwal) |url=https://paleobiodb.org/classic/checkTaxonInfo?taxon_no=64546&is_real_user=1 |url-status=live |archive-url=https://web.archive.org/web/20200712051049/https://paleobiodb.org/classic/checkTaxonInfo?taxon_no=64546&is_real_user=1 |archive-date=12 July 2020 |access-date=11 July 2020 |website=PBDB.org}}</ref>
| image = Нарвал в российской Арктике.jpg
| image2 = Narwhal_size.svg
| image2_caption = Size compared to an average human
| image2_alt = Diagram showing a narwhal and scuba diver from the side: the body of the whale is about three times longer than a [[human]].
| status = LC
| status_system = IUCN3.1
| status_ref = <ref name="IUCN2017">{{cite iucn|last1=Lowry|first1=L.|last2=Laidre|first2=K.|last3=Reeves|first3=R.|title=''Monodon monoceros''|doi=10.2305/IUCN.UK.2017-3.RLTS.T13704A50367651.en|year=2017}}</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 |url-status=live |archive-url=https://web.archive.org/web/20171205014647/https://cites.org/eng/app/appendices.php |archive-date=5 December 2017 |access-date=14 January 2022 |website=cites.org}}</ref>
| display_parents = 2
| genus = Monodon
| parent_authority = [[Carl Linnaeus|Linnaeus]], [[10th edition of Systema Naturae|1758]]
| species = monoceros
| authority = [[Carl Linnaeus|Linnaeus]], [[10th edition of Systema Naturae|1758]]
| range_map = Monodon monoceros distribution map.svg
| range_map_caption = Distribution of narwhal populations 
| range_map_upright = 0.7
}}

The '''narwhal''' ('''''Monodon monoceros''''') is a [[species]] of [[toothed whale]] native to the [[Arctic]]. It is the only member of the [[genus]] '''''Monodon''''' and one of two living representatives of the family [[Monodontidae]]. The narwhal is a stocky cetacean with a relatively blunt snout, a large [[Melon (whale)|melon]], and a shallow ridge in place of a [[dorsal fin]]. Males of this species have a large ({{cvt|1.5|-|3.0|m}}) long [[tusk]], which is a protruding left [[Canine tooth|canine]] thought to function as a weapon, a tool for feeding, in [[sexual selection|attracting mates]] or sensing water salinity. Specially adapted [[slow-twitch muscle]]s, along with the jointed neck vertebrae and shallow dorsal ridge allow for easy movement through the Arctic environment, where the narwhal spends extended periods at great depths. The narwhal's geographic range overlaps with that of the similarly built and closely related [[beluga whale]], and the animals are known to [[interbreed]].

Narwhals inhabit the [[Arctic waters]] of Canada, Greenland and Russia. Every year, they [[seasonal migration|migrate]] to ice-free summering grounds, usually in shallow waters, and often [[Philopatry|return]] to the same sites in subsequent years. Their diet mainly consists of [[Arctogadus glacialis|polar]] and [[Boreogadus saida|Arctic cod]], [[Greenland halibut]], [[cuttlefish]], [[shrimp]], and [[armhook squid]]. Diving to depths of up to {{cvt|2370|m}}, the narwhal is among the deepest-diving [[cetacean]]s. The animals typically travel in groups of three to eight, with aggregations of up to 1,000 occurring in the summer months. Narwhals mate among the offshore [[pack ice]] from March to May, and the young are born between July and August of the following year. When communicating amongst themselves, narwhals use a variety of clicks, whistles and knocks.

There are an estimated 170,000 living narwhals, and the species is listed as being of [[least concern]] by the [[International Union for Conservation of Nature]] (IUCN). The population is threatened by the [[effects of climate change]], such as [[Arctic warming|reduction in ice cover]] and human activities such as [[pollution]] and [[hunting]]. Narwhals have been hunted for thousands of years by [[Inuit]] in northern Canada and Greenland for [[Whale meat|meat]] and [[ivory]], and regulated subsistence hunting continues to this day.

== Taxonomy ==

The narwhal was scientifically described by [[Carl Linnaeus]] in his 1758 publication [[10th edition of Systema Naturae|''Systema Naturae'']].<ref name="Linnaeus">{{Cite book |last=Linnaeus |first=Carl |author-link=Carl Linnaeus |title=Systema naturae per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata |publisher=Lars Salvius |year=1758 |location=Stockholm |page=75 |language=la |chapter=''Monodon monoceros'' |chapter-url=https://gdz.sub.uni-goettingen.de/id/PPN362053006?tify=%7B%22pages%22%3A%5B78%2C79%5D%2C%22pan%22%3A%7B%22x%22%3A1.154%2C%22y%22%3A0.647%7D%2C%22view%22%3A%22scan%22%2C%22zoom%22%3A0.498%7D}}</ref> The word "narwhal" comes from the [[Old Norse]] {{Lang|non|nárhval}}, meaning 'corpse-whale', which possibly refers to the animal's grey, mottled skin and its habit of remaining motionless when at the water's surface, a behaviour known as "logging" that usually happens in the summer.<ref name="Fisheries and Oceans Canada">{{Cite web |year=2007 |title=The narwhal: unicorn of the seas |url=http://www.dfo-mpo.gc.ca/science/publications/uww-msm/pdf/narwhal-narval-eng.pdf |url-status=live |archive-url=https://web.archive.org/web/20130710194915/http://www.dfo-mpo.gc.ca/Science/publications/uww-msm/pdf/narwhal-narval-eng.pdf |archive-date=10 July 2013 |access-date=10 July 2013 |publisher=Fisheries and Oceans Canada}}</ref><ref name="WinterWhales">{{Cite book |last1=Heide-Jørgensen |first1=M. P. |title=Greenland's Winter Whales: The Beluga, the Narwhal and the Bowhead Whale |last2=Laidre |first2=K. L. |publisher=Ilinniusiorfik Undervisningsmiddelforlag, Nuuk, Greenland |year=2006 |isbn=87-7975-299-3 |pages=100–125}}</ref> The scientific name, ''Monodon monoceros'', is derived from [[Ancient Greek]], meaning 'single-tooth single-horn'.<ref>{{Cite book |last=Webster |first=Noah |title=An American Dictionary of the English Language |date=1880 |publisher=G. & C. Merriam |page=854 |chapter=Narwhal |chapter-url=https://books.google.com/books?id=7MVHakLeewQC&pg=PA854}}</ref>

The narwhal is most closely related to the [[beluga whale]] (''Delphinapterus leucas''). Together, these two species comprise the only [[Neontology|extant]] members of the family [[Monodontidae]]. Monodontids are distinguished by their pronounced [[melon (whale)|melon]]s (acoustic sensory organs), short [[snout]]s and the absence of a true [[dorsal fin]].<ref name="EoM">{{Cite book |last=Brodie, Paul |url=https://archive.org/details/encyclopediaofma00mals_0/page/200 |title=The Encyclopedia of Mammals |publisher=Facts on File |year=1984 |isbn=0-87196-871-1 |editor-last=Macdonald, D. |location=New York |pages=[https://archive.org/details/encyclopediaofma00mals_0/page/200 200–203]}}</ref><ref name=":22">{{Cite book |last=Nowak |first=Ronald M. |url=http://archive.org/details/walkersmarinemam0000nowa |title=Walker's marine mammals of the world |date=2003 |publisher=Baltimore, Md. : Johns Hopkins University Press |others=Internet Archive |isbn=978-0-8018-7343-0 |pages=135–137}}</ref>

Although the narwhal and beluga are classified as separate genera, there is some evidence of [[interbreeding]] between the two. Most prominent are the remains of a whale, described by marine zoologists as unlike any known species, which were found in West Greenland around 1990. It had features midway between a narwhal and a beluga, indicating that the remains belonged to a [[Hybrid (biology)|hybrid]] between the two species (a '[[narluga]]');<ref name=":6">{{Cite journal |last1=Heide-Jørgensen |first1=Mads P. |last2=Reeves |first2=Randall R. |date=July 1993 |title=Description of an anomalous Monodontid skull from West Greenland: a possible hybrid? |url=https://onlinelibrary.wiley.com/doi/10.1111/j.1748-7692.1993.tb00454.x |journal=Marine Mammal Science |language=en |volume=9 |issue=3 |pages=258–268 |bibcode=1993MMamS...9..258H |doi=10.1111/j.1748-7692.1993.tb00454.x |issn=0824-0469|url-access=subscription }}</ref> this was confirmed by a 2019 [[DNA analysis]].<ref>{{Cite journal |last1=Skovrind |first1=Mikkel |last2=Castruita |first2=Jose Alfredo Samaniego |last3=Haile |first3=James |last4=Treadaway |first4=Eve C. |last5=Gopalakrishnan |first5=Shyam |last6=Westbury |first6=Michael V. |last7=Heide-Jørgensen |first7=Mads Peter |last8=Szpak |first8=Paul |last9=Lorenzen |first9=Eline D. |date=20 June 2019 |title=Hybridization between two high Arctic cetaceans confirmed by genomic analysis |journal=Scientific Reports |volume=9 |issue=1 |page=7729 |bibcode=2019NatSR...9.7729S |doi=10.1038/s41598-019-44038-0 |issn=2045-2322 |pmc=6586676 |pmid=31221994}}</ref> Whether the hybrid itself [[Hybrid (biology)#Mechanisms of reproductive isolation|could breed]] remains unknown.<ref name=":6" /><ref>{{Cite web |last=Pappas |first=Stephanie |date=20 June 2019 |title=First-ever beluga–narwhal hybrid found in the Arctic |url=https://www.livescience.com/65757-first-beluga-narwhal-hybrid.html |url-status=live |archive-url=https://web.archive.org/web/20190620233552/https://www.livescience.com/65757-first-beluga-narwhal-hybrid.html |archive-date=20 June 2019 |access-date=20 June 2019 |website=[[Live Science]]}}</ref>

=== Evolution ===

Results of a genetic study reveal that [[porpoise]]s and monodontids are closely related, forming a separate [[clade]] which diverged from other [[Delphinoidea|dolphin]]s about 11 [[million years ago]] (mya).<ref>{{Cite journal |last1=Waddell |first1=Victor G. |last2=Milinkovitch |first2=Michel C. |last3=Bérubé |first3=Martine |last4=Stanhope |first4=Michael J. |date=1 May 2000 |title=Molecular phylogenetic examination of the ''Delphinoidea'' trichotomy: congruent evidence from three nuclear loci indicates that porpoises (''Phocoenidae'') share a more recent common ancestry with white whales (''Monodontidae'') than they do with true dolphins (''Delphinidae'') |url=https://www.sciencedirect.com/science/article/pii/S1055790399907510 |journal=Molecular Phylogenetics and Evolution |volume=15 |issue=2 |pages=314–318 |bibcode=2000MolPE..15..314W |doi=10.1006/mpev.1999.0751 |issn=1055-7903 |pmid=10837160|url-access=subscription }}</ref> A 2018 molecular analysis of monodontid fossils indicates that they separated from Phocoenidae (porpoises) around 10.82 to 20.12 mya, and they are considered to be [[sister taxon|sister taxa]].<ref>{{Cite journal |last1=Racicot |first1=Rachel A. |last2=Darroch |first2=Simon A. F. |last3=Kohno |first3=Naoki |date=October 2018 |title=Neuroanatomy and inner ear labyrinths of the narwhal, ''Monodon monoceros'', and beluga, ''Delphinapterus leucas'' (Cetacea: ''Monodontidae'') |journal=Journal of Anatomy |language=en |volume=233 |issue=4 |pages=421–439 |doi=10.1111/joa.12862 |issn=0021-8782 |pmc=6131972 |pmid=30033539}}</ref> A later [[phylogenetic analysis|phylogenetic study]] conducted in 2020 suggested that the narwhal split from the beluga whale around 4.98 mya, based on data from [[mitochondrial DNA]].<ref>{{Cite journal |last1=Louis |first1=Marie |last2=Skovrind |first2=Mikkel |last3=Samaniego Castruita |first3=Jose Alfredo |last4=Garilao |first4=Cristina |last5=Kaschner |first5=Kristin |last6=Gopalakrishnan |first6=Shyam |last7=Haile |first7=James S. |last8=Lydersen |first8=Christian |last9=Kovacs |first9=Kit M. |last10=Garde |first10=Eva |last11=Heide-Jørgensen |first11=Mads Peter |last12=Postma |first12=Lianne |last13=Ferguson |first13=Steven H. |last14=Willerslev |first14=Eske |last15=Lorenzen |first15=Eline D. |date=29 April 2020 |title=Influence of past climate change on phylogeography and demographic history of narwhals (''Monodon monoceros'') |journal=Proceedings of the Royal Society B: Biological Sciences |language=en |volume=287 |issue=1925 |article-number=20192964 |doi=10.1098/rspb.2019.2964 |issn=0962-8452 |pmc=7211449 |pmid=32315590}}</ref>

The fossil species ''[[Casatia thermophila]]'' of [[early Pliocene]] central Italy was described as a possible narwhal ancestor when it was discovered in 2019. ''[[Bohaskaia]]'', ''[[Denebola brachycephala|Denebola]]'' and ''[[Haborodelphis]]'' are other extinct genera known from the [[Pliocene]] of the United States.<ref name=":14" /><ref name=":2" /><ref>{{Cite journal |last1=Ichishima |first1=Hiroto |last2=Furusawa |first2=Hitoshi |last3=Tachibana |first3=Makino |last4=Kimura |first4=Masaichi |date=May 2019 |editor-last=Hautier |editor-first=Lionel |title=First monodontid cetacean (Odontoceti, Delphinoidea) from the early Pliocene of the north-western Pacific Ocean |url=https://onlinelibrary.wiley.com/doi/10.1002/spp2.1244 |journal=Papers in Palaeontology |language=en |volume=5 |issue=2 |pages=323–342 |bibcode=2019PPal....5..323I |doi=10.1002/spp2.1244 |issn=2056-2799|url-access=subscription }}</ref> Fossil evidence shows that prehistoric monodontids lived in tropical waters. They may have migrated to Arctic and subarctic waters in response to changes in the marine food chain.<ref name=":14" /><ref name=":2">{{Cite journal |last1=Vélez-Juarbe |first1=Jorge |last2=Pyenson |first2=Nicholas D. |date=1 March 2012 |title=''Bohaskaia monodontoides'', a new monodontid (Cetacea, ''Odontoceti'', ''Delphinoidea'') from the Pliocene of the western North Atlantic Ocean |url=https://www.tandfonline.com/doi/full/10.1080/02724634.2012.641705 |journal=Journal of Vertebrate Paleontology |language=en |volume=32 |issue=2 |pages=476–484 |bibcode=2012JVPal..32..476V |doi=10.1080/02724634.2012.641705 |issn=0272-4634 |s2cid=55606151|url-access=subscription }}</ref>

The following [[phylogenetic tree]] is based on a 2019 study of the family Monodontidae.<ref name=":14">{{Cite journal |last1=Bianucci |first1=Giovanni |last2=Pesci |first2=Fabio |last3=Collareta |first3=Alberto |last4=Tinelli |first4=Chiara |date=4 May 2019 |title=A new ''Monodontidae'' (Cetacea, ''Delphinoidea'') from the lower Pliocene of Italy supports a warm-water origin for narwhals and white whales |url=https://www.tandfonline.com/doi/full/10.1080/02724634.2019.1645148 |journal=Journal of Vertebrate Paleontology |language=en |volume=39 |issue=3 |article-number=e1645148 |bibcode=2019JVPal..39E5148B |doi=10.1080/02724634.2019.1645148 |issn=0272-4634 |s2cid=202018525 |access-date=21 January 2024 |hdl-access=free |hdl=11568/1022436}}</ref>

{{clade
|1={{extinct}}''[[Kentriodon|Kentriodon pernix]]''
   |2={{clade
      |1={{clade
         |1=''[[Tursiops truncatus]]'' (common bottlenose dolphin)
         |2=''[[Phocoena phocoena]]'' (harbour porpoise)
         }}
      |label2=[[Monodontidae]]
      |2={{clade
         |1={{extinct}}''[[Haborodelphis|Haborodelphis japonicus]]''
         |2={{clade
            |1={{extinct}}''[[Denebola brachycephala]]''
            |2={{clade
               |1={{clade
                  |1={{extinct}}''[[Bohaskaia monodontoides]]''
                  |2='''''Monodon monoceros'''''
                  }}
               |2={{clade
                  |1={{clade
                     |1={{extinct}}''[[Casatia thermophila]]''
                     |2=[[Museum of Natural Sciences|IRSNB]] M 1922
                     }}
                  |2=''[[Delphinapterus leucas]]'' (beluga whale)
                  }}
               }}
            }}
         }}
      }}
   }}

== Description ==
{{Multiple image 
|image1=Нарвалы в южной части архипелага Земля Франца-Иосифа.tif
|caption1=Narwhals near the water surface
|alt1=Two narwhals at the water surface. They have irregular markings over a white background, extremely small pectoral fins and a large, broad tail.
|image2=Monodon monoceros NOAA.jpg
|caption2=Illustration of a narwhal
|alt3=A narwhal in a white background. Note the blackish-brown markings over the white skin, and the long tusk.
|direction=vertical
}}

The narwhal has a robust body with a short, blunt snout, small upcurved flippers, and convex to concave tail flukes. Adults measure {{cvt|3.0|to|5.5|m}} in length and weigh {{cvt|800|to|1600|kg}}.<ref name="Macdonald">{{Cite book |last1=Macdonald |first1=David Whyte |url=https://books.google.com/books?id=GNBwQgAACAAJ |title=Mammals of Europe |last2=Barrett |first2=Priscilla |date=2001 |publisher=Princeton University Press |isbn=0-691-09160-9 |page=173 |language=en |access-date=27 January 2024 |archive-url=https://web.archive.org/web/20240128091510/https://books.google.com/books?id=GNBwQgAACAAJ |archive-date=28 January 2024 |url-status=live}}</ref><ref name=":21">{{Cite journal |last1=Reeves |first1=Randall R. |last2=Tracey |first2=Sharon |date=15 April 1980 |title=''Monodon monoceros'' |journal=Mammalian Species |issue=127 |pages=1–7 |doi=10.2307/3503952 |issn=0076-3519 |jstor=3503952}}</ref><ref name=":20">{{Cite book |last1=Webber |first1=Marc A. |url=https://books.google.com/books?id=sc-cBAAAQBAJ&dq=Narwhals+have+short+bodies&pg=PA172 |title=Marine Mammals of the World: A Comprehensive Guide to Their Identification |last2=Jefferson |first2=Thomas Allen |last3=Pitman |first3=Robert L. |date=28 July 2015 |publisher=Academic Press |isbn=978-0-12-409592-2 |page=172 |language=en}}</ref> Male narwhals attain [[sexual maturity]] at 12 to 20 years of age, reaching a length of {{cvt|3.5|to|4.0|m}}. Females reach sexual maturity at a younger age, between 8 and 9 years old, when they are about {{cvt|3.4|m}} long.<ref name=":4" /> On average, males are about {{cvt|70|cm}} longer and more than 75% heavier than females.<ref>{{Cite journal |last=Kingsley |first=Michael |date=October 1989 |title=Population dynamics of the narwhal Monodon monoceros: an initial assessement (Odontoceti: Monodontidae) |journal=Journal of Zoology |volume=219 |issue=2 |pages=201–208 |doi=10.1111/j.1469-7998.1989.tb02576.x |issn=0952-8369}}</ref>

The colouration of the narwhal consists of a [[Mottle|mottled pattern]], with blackish-brown markings over a white background. At birth, the skin is light grey, and when sexually mature, white patches grow on the [[navel]] and [[genital slit]];<ref name="WinterWhales" /> such whitening occurs throughout life, resulting in aged narwhals being almost purely white.<ref name=":20" /> Unlike most whales, the narwhal has a shallow dorsal ridge, rather than a dorsal fin, possibly an [[evolutionary adaptation]] to make swimming under ice easier or to facilitate rolling.<ref>{{Cite journal |last1=Dietz |first1=Rune |last2=Shapiro |first2=Ari D. |last3=Bakhtiari |first3=Mehdi |last4=Orr |first4=Jack |last5=Tyack |first5=Peter L |last6=Richard |first6=Pierre |last7=Eskesen |first7=Ida Grønborg |last8=Marshall |first8=Greg |date=19 November 2007 |title=Upside-down swimming behaviour of free-ranging narwhals |journal=BMC Ecology |volume=7 |issue=1 |page=14 |bibcode=2007BMCE....7...14D |doi=10.1186/1472-6785-7-14 |issn=1472-6785 |pmc=2238733 |pmid=18021441 |doi-access=free}}</ref> The neck [[vertebrae]] are also jointed, instead of being fused as in most whales, which allows for a greater range of neck flexibility. These characteristics are shared by the beluga whale.<ref name=":22" /> Furthermore, male and female narwhals have differently shaped tail flukes; the former are bent inward, while the latter are swept back on the front margins. This is thought to be an adaptation for reducing [[Drag (physics)|drag]] caused by the tusk.<ref name=":11">{{Cite journal |last1=Fontanella |first1=Janet E. |last2=Fish |first2=Frank E. |last3=Rybczynski |first3=Natalia |last4=Nweeia |first4=Martin T. |last5=Ketten |first5=Darlene R. |date=October 2011 |title=Three-dimensional geometry of the narwhal (''Monodon monoceros'') flukes in relation to hydrodynamics |url=https://onlinelibrary.wiley.com/doi/10.1111/j.1748-7692.2010.00439.x |journal=Marine Mammal Science |language=en |volume=27 |issue=4 |pages=889–898 |bibcode=2011MMamS..27..889F |doi=10.1111/j.1748-7692.2010.00439.x |issn=0824-0469 |hdl-access=free |hdl=1912/4924}}</ref>

The [[skeletal muscle]]s of narwhals are highly adapted for prolonged periods of deep-sea foraging. During such activities, oxygen is reserved in the muscles, which are typically [[Slow-twitch muscle|slow-twitch]], enabling greater endurance and manouverability.<ref>{{Cite journal |last1=Pagano |first1=Anthony M. |last2=Williams |first2=Terrie M. |date=15 February 2021 |title=Physiological consequences of Arctic sea ice loss on large marine carnivores: unique responses by polar bears and narwhals |journal=Journal of Experimental Biology |volume=224 |issue=Suppl_1 |article-number=jeb228049 |doi=10.1242/jeb.228049 |issn=0022-0949 |pmid=33627459 |bibcode=2021JExpB.224B8049P }}</ref> Narwhals also have a comparatively high amount of [[myoglobin]] in their body, which helps to facilitate deeper dives.<ref name=":8" /> It has a dense layer of [[blubber]], around {{cvt|50|to|100|mm}} thick. This fat accounts for a third of the body mass and helps insulate from cold ocean temperatures.<ref name="Fisheries and Oceans Canada" /><ref name=":21" /><ref>{{Cite journal |last=Reidenberg |first=Joy S. |date=June 2007 |title=Anatomical adaptations of aquatic mammals |url=https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.20541 |journal=The Anatomical Record |language=en |volume=290 |issue=6 |pages=507–513 |doi=10.1002/ar.20541 |issn=1932-8486 |pmid=17516440}}</ref>

=== Tusk and dentition ===
[[File:Narwhal tusk, 1701-1930 Wellcome L0059030.jpg|thumb|Narwhal tusk|alt=The tusk of a male narwhal on display. The white tusk is long and shaped like a spiral.]]

The most conspicuous trait of male narwhals is a long, spiralled tusk, which is a [[canine tooth]] that projects from the left side of the upper jaw.<ref name=":20" /><ref name="Nweeia et al.">{{Cite journal |last1=Nweeia |first1=Martin T. |last2=Eichmiller |first2=Frederick C. |last3=Hauschka |first3=Peter V. |last4=Donahue |first4=Gretchen A. |last5=Orr |first5=Jack R. |last6=Ferguson |first6=Steven H. |last7=Watt |first7=Cortney A. |last8=Mead |first8=James G. |last9=Potter |first9=Charles W. |last10=Dietz |first10=Rune |last11=Giuseppetti |first11=Anthony A. |last12=Black |first12=Sandie R. |last13=Trachtenberg |first13=Alexander J. |last14=Kuo |first14=Winston P. |date=18 March 2014 |title=Sensory ability in the narwhal tooth organ system |url=https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.22886 |url-status=live |journal=The Anatomical Record |language=en |volume=297 |issue=4 |pages=599–617 |doi=10.1002/ar.22886 |issn=1932-8486 |pmid=24639076 |archive-url=https://web.archive.org/web/20240124201533/https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.22886 |archive-date=24 January 2024 |access-date=24 January 2024}}</ref> Both sexes have a pair of tusks embedded in the upper jaw, which in males erupt from the lip somewhere between two and three years of age.<ref name=":20" /> The tusk grows throughout the animal's life, reaching lengths of {{cvt|1.5|to|3|m}}.<ref>{{Cite journal |last1=Dietz |first1=Rune |last2=Desforges |first2=Jean-Pierre |last3=Rigét |first3=Frank F. |last4=Aubail |first4=Aurore |last5=Garde |first5=Eva |last6=Ambus |first6=Per |last7=Drimmie |first7=Robert |last8=Heide-Jørgensen |first8=Mads Peter |last9=Sonne |first9=Christian |date=10 May 2021 |title=Analysis of narwhal tusks reveals lifelong feeding ecology and mercury exposure |url=https://www.sciencedirect.com/science/article/pii/S0960982221002256 |url-status=live |journal=Current Biology |volume=31 |issue=9 |pages=2012–2019.e2 |bibcode=2021CBio...31E2012D |doi=10.1016/j.cub.2021.02.018 |issn=0960-9822 |pmid=33705717 |archive-url=https://web.archive.org/web/20240126170410/https://www.sciencedirect.com/science/article/pii/S0960982221002256 |archive-date=26 January 2024 |access-date=26 January 2024}}</ref><ref>{{Cite book |last=Dipper |first=Frances |url=https://books.google.com/books?id=lfYlEAAAQBAJ&dq=narwhal+weight&pg=PA436 |title=The Marine World: A Natural History of Ocean Life |date=8 June 2021 |publisher=Princeton University Press |isbn=978-0-691-23244-7 |page=347 |language=en}}</ref><ref name=":1" /> It is hollow and weighs up to {{convert|7.45|kg|lb|abbr=on}}. Some males may grow two tusks, occurring when the right canine also protrudes through the lip.<ref name=":1">{{Cite journal |last1=Garde |first1=Eva |last2=Peter Heide-Jørgensen |first2=Mads |last3=Ditlevsen |first3=Susanne |last4=Hansen |first4=Steen H. |date=January 2012 |title=Aspartic acid racemization rate in narwhal (''Monodon monoceros'') eye lens nuclei estimated by counting of growth layers in tusks |url=https://polarresearch.net/index.php/polar/article/view/2584 |journal=Polar Research |language=en |volume=31 |issue=1 |article-number=15865 |doi=10.3402/polar.v31i0.15865 |issn=1751-8369 |doi-access=free}}</ref><ref>{{Cite thesis |last=Lee |first=David S. |title=The ecological and social dynamics of Inuit narwhal foraging at Pond Inlet, Nunavut |date=2005 |degree=Doctor of Philosophy |publisher=McGill University |url=https://escholarship.mcgill.ca/concern/theses/q237hs40f |pages=7–13}}</ref> Females rarely grow tusks: when they do, the tusks are typically smaller than those of males, with less noticeable spirals.<ref name="WinterWhales" /><ref>{{Cite journal |last1=Garde |first1=Eva |last2=Heide-Jørgensen |first2=Mads Peter |date=3 June 2022 |title=Tusk anomalies in narwhals (Monodon monoceros) from Greenland |journal=Polar Research |volume=41 |doi=10.33265/polar.v41.8343 |issn=0800-0395 |doi-access=free}}</ref>

Current [[scientific consensus]] indicates that narwhal tusks are [[secondary sexual characteristics]] which indicate social status. Further functions of the narwhal tusk are debated: while some biologists suggest that narwhals use their tusks in fights, others argue that they may be of use in feeding.<ref name=":19">{{Citation |last1=Loch |first1=Carolina |title=Skulls, teeth, and sex |date=2023 |work=Sex in Cetaceans: Morphology, Behavior, and the Evolution of Sexual Strategies |pages=51–64 |editor-last=Würsig |editor-first=Bernd |editor-last2=Orbach |editor-first2=Dara N. |place=Cham |publisher=Springer International Publishing |language=en |doi=10.1007/978-3-031-35651-3_3 |isbn=978-3-031-35651-3 |last2=Fordyce |first2=R. Ewan |last3=Werth |first3=Alexander |doi-access=free}}</ref> The tusk is also a highly [[innervate]]d [[sensory organ]] with millions of [[nerve ending]]s, allowing the narwhal to sense temperature variability in its surroundings.<ref name="Nweeia et al." /> These nerves may also be able to detect changes in particle concentration and water pressure.<ref name="Broad">{{Cite news |last=Broad |first=William |date=13 December 2005 |title=It's sensitive. Really. |url=https://www.nytimes.com/2005/12/13/science/its-sensitive-really.html?_r=0 |url-status=live |archive-url=https://web.archive.org/web/20240128091613/https://www.nytimes.com/2005/12/13/science/its-sensitive-really.html?_r=0 |archive-date=28 January 2024 |access-date=22 February 2017 |work=The New York Times}}</ref><ref name=":0">{{Cite web |last=Vincent, James |date=19 March 2014 |title=Scientists suggest they have the answer to the mystery of the narwhal's tusk |url=https://www.independent.co.uk/news/science/scientists-solve-the-mystery-of-the-narwhals-tusk-9202935.html |url-access=subscription |url-status=live |archive-url=https://ghostarchive.org/archive/20220618/https://www.independent.co.uk/news/science/scientists-solve-the-mystery-of-the-narwhals-tusk-9202935.html |archive-date=18 June 2022 |access-date=31 March 2014 |website=[[Independent.co.uk]]}}</ref> According to Martin Nweeia, male narwhals may rid themselves of encrustations on their tusks by rubbing them together, as opposed to posturing displays of aggressive male-to-male rivalry.<ref name="Broad" /><ref name=":0" /> [[Unmanned aerial vehicle|Drone]] footage from August 2016 in Tremblay Sound, [[Nunavut]], revealed that narwhals used their tusks to tap and [[wikt:stun#Verb|stun]] small [[Arctic cod]], making them easier to catch for feeding.<ref name=":19" /><ref>{{Cite news |date=17 May 2017 |title=Drone-shot video may have just solved 400-year debate over what narwhal tusks are used for |url=https://nationalpost.com/news/canada/drone-shot-video-may-have-just-solved-400-year-debate-over-what-narwhal-tusks-are-used-for |access-date=17 July 2024 |work=National Post}}</ref> Females, who usually do not have tusks, live longer than males, hence the tusk cannot be essential to the animal's survival. It is generally accepted that the primary function of the narwhal tusk is associated with [[sexual selection]].<ref name=":19" /><ref name=":13">{{Cite journal |last1=Kelley |first1=Trish C. |last2=Stewart |first2=Robert E. A. |last3=Yurkowski |first3=David J. |last4=Ryan |first4=Anna |last5=Ferguson |first5=Steven H. |date=April 2015 |title=Mating ecology of beluga (''Delphinapterus leucas'') and narwhal (''Monodon monoceros'') as estimated by reproductive tract metrics |url=https://onlinelibrary.wiley.com/doi/10.1111/mms.12165 |journal=Marine Mammal Science |language=en |volume=31 |issue=2 |pages=479–500 |bibcode=2015MMamS..31..479K |doi=10.1111/mms.12165 |issn=0824-0469|url-access=subscription }}</ref>

Alongside its tusk, the narwhal has a single pair of small [[vestigial]] teeth that reside in open [[tooth socket]]s in the upper jaw. These teeth, which differ in form and composition, encircle the exposed tooth sockets laterally, posteriorly, and ventrally.<ref name="Nweeia et al." /><ref name="smiths">{{Cite web |date=18 April 2012 |title=For a dentist, the narwhal's smile is a mystery of evolution |url=http://insider.si.edu/2012/04/for-dentist-the-narwhals-smile-is-a-mystery-of-evolution/ |url-status=live |archive-url=https://web.archive.org/web/20160914121508/http://insider.si.edu/2012/04/for-dentist-the-narwhals-smile-is-a-mystery-of-evolution/ |archive-date=14 September 2016 |access-date=6 September 2016 |publisher=Smithsonian Insider}}</ref> Vestigial teeth in male narwhals are commonly shed in the [[palate]]. The varied morphology and anatomy of small teeth indicate a path of evolutionary obsolescence.<ref name="Nweeia et al." /><ref>{{Cite journal |last1=Nweeia |first1=Martin T. |last2=Eichmiller |first2=Frederick C. |last3=Hauschka |first3=Peter V. |last4=Tyler |first4=Ethan |last5=Mead |first5=James G. |last6=Potter |first6=Charles W. |last7=Angnatsiak |first7=David P. |last8=Richard |first8=Pierre R. |last9=Orr |first9=Jack R. |last10=Black |first10=Sandie R. |date=30 March 2012 |title=Vestigial tooth anatomy and tusk nomenclature for ''Monodon Monoceros'' |journal=The Anatomical Record |volume=295 |issue=6 |pages=1006–1016 |doi=10.1002/ar.22449 |issn=1932-8486 |pmid=22467529}}</ref>

== Distribution ==

[[File:Особи нарвала в Арктике.jpg|thumb|Pod of six narwhals|alt=Six narwhals near the water surface in the open ocean.]]

The narwhal is found in the Atlantic and Russian areas of the [[Arctic Ocean]]. Individuals are commonly recorded in the [[Canadian Arctic Archipelago]],<ref>{{Citation |last=Heide-Jørgensen |first=M. P. |title=Narwhal: ''Monodon monoceros'' |date=2018 |pages=627–631 |editor-last=Würsig |editor-first=Bernd |editor-last2=Thewissen |editor-first2=J. G. M. |editor-last3=Kovacs |editor-first3=Kit M. |url=https://www.sciencedirect.com/science/article/pii/B9780128043271000133 |access-date=27 January 2024 |archive-url=https://web.archive.org/web/20230120021454/https://www.sciencedirect.com/science/article/pii/B9780128043271000133 |archive-date=20 January 2023 |url-status=live |publisher=Academic Press |isbn=978-0-12-804327-1 |encyclopedia=Encyclopedia of Marine Mammals (Third Edition)}}</ref><ref>{{Cite journal |last1=Belikov |first1=Stanislav E. |last2=Boltunov |first2=Andrei N. |date=21 July 2002 |title=Distribution and migrations of cetaceans in the Russian Arctic according to observations from aerial ice reconnaissance |url=https://septentrio.uit.no/index.php/NAMMCOSP/article/view/2838 |url-status=live |journal=NAMMCO Scientific Publications |language=en |volume=4 |pages=69–86 |doi=10.7557/3.2838 |issn=2309-2491 |archive-url=https://web.archive.org/web/20240127204114/https://septentrio.uit.no/index.php/NAMMCOSP/article/view/2838 |archive-date=27 January 2024 |access-date=27 January 2024}}</ref> such as in the northern part of [[Hudson Bay]], in [[Hudson Strait]], in [[Baffin Bay]], off the east coast of Greenland and in a strip running east from the northern end of Greenland to eastern Russia ([[170th meridian east|170° east]]). Land in this strip includes [[Svalbard]], [[Franz Joseph Land]] and [[Severnaya Zemlya]].<ref name="WinterWhales" /> The northernmost sightings of narwhals occurred north of Franz Joseph Land, at about [[85th parallel north|85° north]].<ref name="WinterWhales" /> There are an estimated 12,500 narwhals in the northern Hudson Bay, whereas around 140,000 reside in Baffin Bay.<ref name=":3">{{Cite journal |last1=Watt |first1=C. A. |last2=Orr |first2=J. R. |last3=Ferguson |first3=S. H. |date=January 2017 |title=Spatial distribution of narwhal (''Monodon monoceros'') diving for Canadian populations helps identify important seasonal foraging areas |url=http://www.nrcresearchpress.com/doi/10.1139/cjz-2016-0178 |url-status=live |journal=Canadian Journal of Zoology |language=en |volume=95 |issue=1 |pages=41–50 |doi=10.1139/cjz-2016-0178 |bibcode=2017CaJZ...95...41W |issn=0008-4301 |archive-url=https://web.archive.org/web/20240128092102/https://cdnsciencepub.com/doi/10.1139/cjz-2016-0178 |archive-date=28 January 2024 |access-date=20 January 2024|url-access=subscription }}</ref>

=== Migration ===
Narwhals exhibit [[seasonal migration]], with a high [[Philopatry|fidelity of return]] to preferred ice-free summering grounds, usually in shallow waters. In summer months, they move closer to the coast, often in pods of 10–100 individuals. In the winter, they move to deeper waters offshore, under thick [[pack ice]], surfacing in narrow fissures or in wider fractures known as [[Lead (sea ice)|leads]].<ref name="WinterWhales" /><ref name="Laidre2005">{{Cite journal |last1=Laidre |first1=K. L. |last2=Heide-Jorgensen |first2=M. P. |date=January 2005 |title=Winter feeding intensity of narwhals (''Monodon monoceros'') |url=https://onlinelibrary.wiley.com/doi/10.1111/j.1748-7692.2005.tb01207.x |journal=Marine Mammal Science |language=en |volume=21 |issue=1 |pages=45–57 |bibcode=2005MMamS..21...45L |doi=10.1111/j.1748-7692.2005.tb01207.x |issn=0824-0469|url-access=subscription }}</ref> As spring comes, these leads open up into channels and the narwhals return to the coastal [[bay]]s.<ref name="Laidre2008">{{Cite journal |last1=Laidre |first1=Kristin L. |last2=Stirling |first2=Ian |last3=Lowry |first3=Lloyd F. |last4=Wiig |first4=Øystein |last5=Heide-Jørgensen |first5=Mads Peter |last6=Ferguson |first6=Steven H. |date=March 2008 |title=Quantifying the sensitivity of Arctic marine mammals to climate-induced habitat change |url=http://doi.wiley.com/10.1890/06-0546.1 |journal=Ecological Applications |language=en |volume=18 |issue=sp2 |pages=S97–S125 |bibcode=2008EcoAp..18S..97L |doi=10.1890/06-0546.1 |issn=1051-0761 |pmid=18494365}}</ref><ref>{{Cite book |last=Paine |first=Stefani Hewlett |url=http://archive.org/details/natureofarcticwh0000pain |title=The nature of Arctic whales: belugas, bowheads and narwhals |date=1995 |publisher=Vancouver : Douglas & McIntyre |others=Internet Archive |isbn=978-1-55054-190-8 |page=24}}</ref> Narwhals in Baffin Bay typically travel to northern Canada and Greenland between June and September. After this period, they travel about {{Convert|1700|km|mi}} south to the [[Davis Strait]], and stay there until April.<ref name=":3" /> During winter, narwhals from Canada and West Greenland regularly visit the pack ice of the Davis Strait and Baffin Bay along the [[continental slope]] which contains less than 5% open water and hosts a high density of [[Greenland halibut]].<ref name= Laidre2004/><ref name="WinterWhales" />

== Behaviour and ecology ==

[[File:Narwhal tail above surface.jpg|thumb|Narwhal tail fluke|alt=Photo depicting narwhal tail flukes, which are broad, flat, and horizontal in shape.]]

Narwhals normally [[Sociality|congregate in groups]] of three to eight individuals. Groups may be "nurseries" with only females and young, or can contain only juveniles or adult males ("bulls"); mixed groups can occur at any time of year.<ref name=":22" /><ref name=":21" /><ref>{{Cite book |last=Beer |first=Amy-Jane |url=http://archive.org/details/encyclopediaofno0000beer |title=Encyclopedia of North American mammals |date=2004 |publisher=San Diego, Calif. : Thunder Bay Press |others=Internet Archive |isbn=978-1-59223-191-1 |page=122}}</ref> In the summer, several groups come together, forming larger aggregations which can contain 500 to over 1,000 individuals.<ref name= Macdonald/><ref name=":20" /> Male narwhals have been observed rubbing each other's tusks, a behaviour known as "tusking".<ref name="Broad" /><ref name="NOAA Ocean Explorer">{{Cite web |title=The biology and ecology of narwhals |url=http://oceanexplorer.noaa.gov/explorations/06arctic/background/biology/biology.html |url-status=live |archive-url=https://web.archive.org/web/20220814234737/https://oceanexplorer.noaa.gov/explorations/06arctic/background/biology/biology.html |archive-date=14 August 2022 |access-date=15 January 2009 |website=noaa.gov |publisher=National Oceanic and Atmospheric Administration}}</ref>

When in their wintering waters, narwhals make some of the deepest dives recorded for cetaceans, diving to at least {{cvt|800|m|ft|-1|abbr=off}} over 15 times per day, with many dives reaching {{cvt|1,500|m|ft|-1|abbr=off}}.<ref name="laidre2003" /><ref>{{Cite journal |last=Kumar |first=Mohi |date=March 2011 |title=Research Spotlight: Narwhals document continued warming of Baffin Bay |url=https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2011EO090009 |journal=Eos, Transactions American Geophysical Union |language=en |volume=92 |issue=9 |page=80 |bibcode=2011EOSTr..92...80K |doi=10.1029/2011EO090009 |issn=0096-3941}}</ref> The greatest dive depth recorded is {{cvt|2370|m|ft}}.<ref name="laidre2003" /><ref name="davis">{{Cite book |last=Davis |first=Randall W. |title=Marine Mammals. Adaptations for an Aquatic Life |publisher=Springer |year=2019 |isbn=978-3-319-98278-6 |location=Berlin/Heidelberg |chapter=Appendix 3. Maximum Recorded Dive Depths and Durations for Marine Mammals}}</ref> Dives last up to 25 minutes, and vary in depth depending on the season and local variation between environments. For example, in the Baffin Bay wintering grounds, narwhals tend to dive deep within the steep coasts, typically south of Baffin Bay. This suggests differences in habitat structure, prey availability, or genetic adaptations between subpopulations. In the northern wintering grounds, narwhals do not dive as deep as the southern population, in spite of greater water depths in these areas. This is mainly attributed to prey being concentrated nearer to the surface, which causes narwhals to alter their foraging strategies.<ref name="laidre2003">{{Cite journal |last1=Laidre |first1=Kristin L. |last2=Heide-Jørgensen |first2=Mads Peter |last3=Dietz |first3=Rune |last4=Hobbs |first4=Roderick C. |last5=Jørgensen |first5=Ole A. |date=17 October 2003 |title=Deep-diving by narwhals (''Monodon monoceros''): differences in foraging behavior between wintering areas? |url=https://www.int-res.com/abstracts/meps/v261/p269-281/ |journal=Marine Ecology Progress Series |language=en |volume=261 |pages=269–281 |bibcode=2003MEPS..261..269L |doi=10.3354/meps261269 |issn=0171-8630}}</ref>

=== Diet ===
Narwhals have a restricted and specialised diet.<ref name="Laidre2005" /><ref name=":18">{{Cite journal |last1=Chambault |first1=P. |last2=Tervo |first2=O. M. |last3=Garde |first3=E. |last4=Hansen |first4=R. G. |last5=Blackwell |first5=S. B. |last6=Williams |first6=T. M. |last7=Dietz |first7=R. |last8=Albertsen |first8=C. M. |last9=Laidre |first9=K. L. |last10=Nielsen |first10=N. H. |last11=Richard |first11=P. |last12=Sinding |first12=M. H. S. |last13=Schmidt |first13=H. C. |last14=Heide-Jørgensen |first14=M. P. |date=29 October 2020 |title=The impact of rising sea temperatures on an Arctic top predator, the narwhal |journal=Scientific Reports |language=en |volume=10 |issue=1 |page=18678 |bibcode=2020NatSR..1018678C |doi=10.1038/s41598-020-75658-6 |issn=2045-2322 |pmc=7596713 |pmid=33122802}}</ref> Due to the lack of well-developed [[dentition]], narwhals are believed to feed by swimming close to prey and [[Suction feeding|sucking]] them into the mouth.<ref>{{Cite journal |last1=Jensen |first1=Frederik H. |last2=Tervo |first2=Outi M. |last3=Heide-Jørgensen |first3=Mads Peter |last4=Ditlevsen |first4=Susanne |date=25 March 2023 |title=Detecting narwhal foraging behaviour from accelerometer and depth data using mixed-effects logistic regression |journal=Animal Biotelemetry |volume=11 |issue=1 |page=14 |bibcode=2023AnBio..11...14J |doi=10.1186/s40317-023-00325-2 |issn=2050-3385 |doi-access=free}}</ref> A study of the stomach contents of 73 narwhals found Arctic cod (''[[Boreogadus|Boreogadus saida]]'') to be the most commonly consumed prey, followed by Greenland halibut (''[[Reinhardtius hippoglossoides]]''). Large quantities of Boreo-Atlantic armhook squid (''[[Gonatus fabricii]]'') were also discovered. Male specimens had a higher likelihood of showing two additional prey species within their stomach contents: polar cod (''[[Arctogadus glacialis]]'') and redfish (''[[Sebastes marinus]]''), both of which are found at depths of more than {{cvt|500|m}}. The study also concluded that the size of prey did not differ between genders or age groups.<ref name="Finley1982" /> Other items found within narwhal stomach contents include [[wolffish]], [[capelin]], [[Skate (fish)|skate]] eggs and sometimes rocks.<ref name= Macdonald/><ref name="Laidre2005" /><ref name="Laidre2004">{{Cite journal |last1=Laidre |first1=K. L. |last2=Heide-Jørgensen |first2=M. P. |last3=Jørgensen |first3=O. A. |last4=Treble |first4=M. A. |date=1 January 2004 |title=Deep-ocean predation by a high Arctic cetacean |journal=ICES Journal of Marine Science |volume=61 |issue=3 |pages=430–440 |bibcode=2004ICJMS..61..430L |doi=10.1016/j.icesjms.2004.02.002 |issn=1095-9289}}</ref>

Narwhal diet varies between seasons. In winter, narwhals feed on [[Demersal fish|demersal]] prey, mostly [[flatfish]], under dense pack ice. During the summer, they eat mostly Arctic cod and Greenland halibut, with other fish such as polar cod making up the remainder of their diet.<ref name="Finley1982">{{Cite journal |last1=Finley |first1=K. J. |last2=Gibb |first2=E. J. |date=December 1982 |title=Summer diet of the narwhal (''Monodon monoceros'') in Pond Inlet, northern Baffin Island |journal=Canadian Journal of Zoology |volume=60 |issue=12 |pages=3353–3363 |doi=10.1139/z82-424 |bibcode=1982CaJZ...60.3353F |issn=0008-4301}}</ref> Narwhals consume more food in the winter months than they do in summer.<ref name="Laidre2005" /><ref name="Laidre2004" />

=== Breeding ===

Most female narwhals reproduce by the time they are six to eight years old.<ref name="Fisheries and Oceans Canada" /> [[courtship display|Courtship]] and [[Reproduction|mating]] behaviour for the species has been recorded from March to May, when they live among offshore pack ice, and is thought to involve a dominant male mating with several partners. The average [[gestation]] period lasts 15 months, and births appear to be most frequent between July and August. Female narwhals have a birth interval of around 2–3 years.<ref name=":4">{{Cite journal |last1=Garde |first1=Eva |last2=Hansen |first2=Steen H. |last3=Ditlevsen |first3=Susanne |last4=Tvermosegaard |first4=Ketil Biering |last5=Hansen |first5=Johan |last6=Harding |first6=Karin C. |last7=Heide-Jørgensen |first7=Mads Peter |date=7 July 2015 |title=Life history parameters of narwhals (''Monodon monoceros'') from Greenland |journal=Journal of Mammalogy |volume=96 |issue=4 |pages=866–879 |doi=10.1093/jmammal/gyv110 |issn=0022-2372 }}</ref><ref name=":24">{{Cite book |url=https://books.google.com/books?id=QynOriR1MxEC&dq=Narwhal+reproduction&pg=PA85 |title=Dolphins, Porpoises and Whales of the World: The IUCN Red Data Book |date=1991 |publisher=IUCN |isbn=2-88032-936-1 |editor-last=Klinowska |editor-first=Margaret |page=79 |language=en |access-date=28 January 2024 |archive-url=https://web.archive.org/web/20240128091605/https://books.google.com/books?id=QynOriR1MxEC&dq=Narwhal+reproduction&pg=PA85#v=onepage&q=Narwhal%20reproduction&f=false |archive-date=28 January 2024 |url-status=live}}</ref><ref>{{Citation |last1=Würsig |first1=Bernd |title=Sex and Behavior |date=2023 |work=Sex in Cetaceans: Morphology, Behavior, and the Evolution of Sexual Strategies |pages=1–27 |editor-last=Würsig |editor-first=Bernd |place=Cham |publisher=Springer International Publishing |language=en |doi=10.1007/978-3-031-35651-3_1 |isbn=978-3-031-35651-3 |last2=Rich |first2=Jacquline |last3=Orbach |first3=Dara N. |editor2-last=Orbach |editor2-first=Dara N. |doi-access=free}}</ref> As with most marine mammals, only a single calf is born, averaging {{cvt|1.5|m|ft|abbr=off}} in length with white or light grey pigmentation.<ref>{{Cite book |last=Tinker |first=Spencer Wilkie |url=https://books.google.com/books?id=ASIVAAAAIAAJ&dq=Narwhal+reproduction&pg=PA213 |title=Whales of the World |date=1988 |publisher=E. J. Brill |isbn=0-935848-47-9 |page=213 |language=en |access-date=28 January 2024 |archive-url=https://web.archive.org/web/20240128091622/https://books.google.com/books?id=ASIVAAAAIAAJ&dq=Narwhal+reproduction&pg=PA213#v=onepage&q=Narwhal%20reproduction&f=false |archive-date=28 January 2024 |url-status=live}}</ref><ref>{{Citation |last=Mann |first=Janet |title=Parental Behavior |date=1 January 2009 |pages=830–836 |editor-last=Perrin |editor-first=William F. |editor-last2=Würsig |editor-first2=Bernd |editor-last3=Thewissen |editor-first3=J. G. M. |url=https://www.sciencedirect.com/science/article/pii/B9780123735539001942 |access-date=17 July 2024 |place=London |publisher=Academic Press |isbn=978-0-12-373553-9|encyclopedia=Encyclopedia of Marine Mammals (Second Edition)}}</ref> Summer population surveys along different coastal inlets of [[Baffin Island]] found that calf numbers varied from 0.05% of 35,000 in [[Admiralty Inlet (Nunavut)|Admiralty Inlet]], to 5% of 10,000 total in [[Eclipse Sound]]. These findings suggest that higher calf counts may reflect calving and nursery habitats in favourable inlets.<ref name="newsci">{{Cite magazine |last=Evans Ogden, Lesley |date=6 January 2016 |title=Elusive narwhal babies spotted gathering at Canadian nursery |url=https://www.newscientist.com/article/dn28729-elusive-narwhal-babies-spotted-gathering-at-canadian-nursery/ |url-status=live |archive-url=https://web.archive.org/web/20160921124956/https://www.newscientist.com/article/dn28729-elusive-narwhal-babies-spotted-gathering-at-canadian-nursery/ |archive-date=21 September 2016 |access-date=6 September 2016 |magazine=New Scientist}}</ref>

Newborn calves begin their lives with a thin layer of blubber. The blubber thickens as they [[lactation|nurse]] their mother's milk, which is rich in fat; calves are dependent on milk for about 20 months.<ref name="Macdonald" /><ref name=":23" /> This long lactation period gives calves time to learn the skills they will need to survive as they mature.<ref name="newsci" /><ref name=":23">{{Cite journal |last1=Zhao |first1=Shu-Ting |last2=Matthews |first2=Cory J. D. |last3=Davoren |first3=Gail K. |last4=Ferguson |first4=Steven H. |last5=Watt |first5=Cortney A. |date=24 June 2021 |title=Ontogenetic profiles of dentine isotopes (δ15N and δ13C) reveal variable narwhal Monodon monoceros nursing duration |url=https://www.int-res.com/abstracts/meps/v668/p163-175/ |journal=Marine Ecology Progress Series |language=en |volume=668 |pages=163–175 |bibcode=2021MEPS..668..163Z |doi=10.3354/meps13738 |issn=0171-8630|url-access=subscription }}</ref> Narwhals are among the few animals that undergo [[menopause]] and live for decades after they have finished breeding. Females in this phase may continue to protect calves in the pod.<ref name=":4" /><ref name="Menopause in narwhals" /> A 2024 study concluded that five species of [[toothed whale]] evolved menopause to acquire higher overall longevity, although their reproductive periods did not change. To explain this, scientists hypothesised that calves of these species require the assistance of (post-)menopausal females for an enhanced chance at survival, as they are extremely difficult for a single female to successfully rear.<ref name="Menopause in narwhals">{{Cite journal |last1=Ellis |first1=Samuel |last2=Franks |first2=Daniel W. |last3=Nielsen |first3=Mia Lybkær Kronborg |last4=Weiss |first4=Michael N. |last5=Croft |first5=Darren P. |date=13 March 2024 |title=The evolution of menopause in toothed whales |journal=Nature |language=en |volume=627 |issue=8004 |pages=579–585 |bibcode=2024Natur.627..579E |doi=10.1038/s41586-024-07159-9 |issn=1476-4687 |pmc=10954554 |pmid=38480878 |doi-access=free}}</ref>

=== Communication ===
{{See also|Whale vocalization}}
Like most toothed whales, narwhals use sound to navigate and hunt for food. They primarily vocalise through clicks, whistles and knocks, created by air movement between chambers near the [[Blowhole (anatomy)|blowhole]].<ref>{{Cite journal |last1=Blackwell |first1=Susanna B. |last2=Tervo |first2=Outi M. |last3=Conrad |first3=Alexander S. |last4=Sinding |first4=Mikkel H. S. |last5=Hansen |first5=Rikke G. |last6=Ditlevsen |first6=Susanne |last7=Heide-Jørgensen |first7=Mads Peter |date=13 June 2018 |title=Spatial and temporal patterns of sound production in East Greenland narwhals |journal=PLOS ONE |language=en |volume=13 |issue=6 |article-number=e0198295 |bibcode=2018PLoSO..1398295B |doi=10.1371/journal.pone.0198295 |issn=1932-6203 |pmc=5999075 |pmid=29897955 |doi-access=free}}</ref><ref name=":25">{{Citation |last=Wei |first=Chong |title=Chapter 17 - Sound production and propagation in cetaceans |date=1 January 2021 |work=Neuroendocrine Regulation of Animal Vocalization |pages=267–295 |editor-last=Rosenfeld |editor-first=Cheryl S. |editor-last2=Hoffmann |editor-first2=Frauke |url=https://www.sciencedirect.com/science/article/pii/B978012815160000013X |access-date=18 July 2024 |publisher=[[Academic Press]] |isbn=978-0-12-815160-0 }}</ref> The frequency of these sounds ranges from 0.3 to 125 [[hertz]], while those used for [[Animal echolocation|echolocation]] typically fall between 19 and 48 hertz.<ref>{{Cite book |last1=Still |first1=Robert |url=https://books.google.com/books?id=z9B-DwAAQBAJ&dq=Narwhal+reproduction&pg=PA161 |title=Europe's Sea Mammals Including the Azores, Madeira, the Canary Islands and Cape Verde: A field guide to the whales, dolphins, porpoises and seals |last2=Harrop |first2=Hugh |last3=Dias |first3=Luís |last4=Stenton |first4=Tim |date=2019 |publisher=Princeton University Press |isbn=978-0-691-19062-4 |page=16 |language=en |access-date=28 January 2024 |archive-url=https://web.archive.org/web/20240128092010/https://books.google.com/books?id=z9B-DwAAQBAJ&dq=Narwhal+reproduction&pg=PA161#v=onepage&q=Narwhal%20reproduction&f=false |archive-date=28 January 2024 |url-status=live}}</ref><ref>{{Cite journal |last1=Miller |first1=Lee A. |last2=Pristed |first2=John |last3=Møshl |first3=Bertel |last4=Surlykke |first4=Annemarie |date=October 1995 |title=The click-sounds of narwhals (''Monodon monoceros'') in Inglefield Bay, Northwest Greenland |url=https://onlinelibrary.wiley.com/doi/10.1111/j.1748-7692.1995.tb00672.x |url-status=live |journal=Marine Mammal Science |language=en |volume=11 |issue=4 |pages=491–502 |bibcode=1995MMamS..11..491M |doi=10.1111/j.1748-7692.1995.tb00672.x |issn=0824-0469 |s2cid=85148204 |archive-url=https://web.archive.org/web/20221005045122/https://onlinelibrary.wiley.com/doi/10.1111/j.1748-7692.1995.tb00672.x |archive-date=5 October 2022 |access-date=27 January 2024|url-access=subscription }}</ref> Sounds are reflected off the sloping front of the skull and focused by the animal's [[Melon (cetacean)|melon]]: a mass of fat which can be controlled through surrounding musculature.<ref name=":25" /><ref>{{Cite journal |last1=Senevirathna |first1=Jayan Duminda Mahesh |last2=Yonezawa |first2=Ryo |last3=Saka |first3=Taiki |last4=Igarashi |first4=Yoji |last5=Funasaka |first5=Noriko |last6=Yoshitake |first6=Kazutoshi |last7=Kinoshita |first7=Shigeharu |last8=Asakawa |first8=Shuichi |date=January 2021 |title=Transcriptomic insight into the melon morphology of toothed whales for aquatic molecular developments |journal=Sustainability |language=en |volume=13 |issue=24 |article-number=13997 |doi=10.3390/su132413997 |bibcode=2021Sust...1313997S |issn=2071-1050 |doi-access=free}}</ref> Echolocation clicks are used for detecting prey and locating barriers at short distances.<ref name=":25" /><ref>{{Cite journal |last1=Zahn |first1=Marie J. |last2=Rankin |first2=Shannon |last3=McCullough |first3=Jennifer L. K. |last4=Koblitz |first4=Jens C. |last5=Archer |first5=Frederick |last6=Rasmussen |first6=Marianne H. |last7=Laidre |first7=Kristin L. |date=12 November 2021 |title=Acoustic differentiation and classification of wild belugas and narwhals using echolocation clicks |journal=Scientific Reports |language=en |volume=11 |issue=1 |page=22141 |bibcode=2021NatSR..1122141Z |doi=10.1038/s41598-021-01441-w |issn=2045-2322 |pmc=8589986 |pmid=34772963}}</ref> Whistles and throbs are most commonly used to communicate with other pod members.<ref name=":25" /><ref>{{Cite journal |last1=Marcoux |first1=Marianne |last2=Auger-Méthé |first2=Marie|author2-link=Marie Auger-Méthé |last3=Humphries |first3=Murray M. |date=October 2012 |title=Variability and context specificity of narwhal (''Monodon monoceros'') whistles and pulsed calls |url=https://onlinelibrary.wiley.com/doi/10.1111/j.1748-7692.2011.00514.x |journal=Marine Mammal Science |language=en |volume=28 |issue=4 |pages=649–665 |bibcode=2012MMamS..28..649M |doi=10.1111/j.1748-7692.2011.00514.x |issn=0824-0469|url-access=subscription }}</ref> Calls recorded from the same pod are more similar than calls from different pods, suggesting the possibility of group- or individual-specific calls. Narwhals sometimes adjust the duration and pitch of their pulsed calls to maximise sound propagation in varying acoustic environments.<ref name="WinterWhales" /><ref>{{Cite journal |last=Shapiro |first=Ari D. |date=1 September 2006 |title=Preliminary evidence for signature vocalizations among free-ranging narwhals (''Monodon monoceros'') |journal=The Journal of the Acoustical Society of America |volume=120 |issue=3 |pages=1695–1705 |bibcode=2006ASAJ..120.1695S |doi=10.1121/1.2226586 |issn=0001-4966 |pmid=17004490 |hdl-access=free |hdl=1912/2355}}</ref> Other sounds produced by narwhals include trumpeting and "squeaking-door sounds".<ref name="Fisheries and Oceans Canada" /> The narwhal vocal repertoire is similar to that of the beluga whale. However, the frequency ranges, durations, and repetition rates of narwhal clicks differ from those of belugas.<ref>{{Cite journal |last1=Jones |first1=Joshua M. |last2=Frasier |first2=Kaitlin E. |last3=Westdal |first3=Kristin H. |last4=Ootoowak |first4=Alex J. |last5=Wiggins |first5=Sean M. |last6=Hildebrand |first6=John A. |date=1 March 2022 |title=Beluga (''Delphinapterus leucas'') and narwhal (''Monodon monoceros'') echolocation click detection and differentiation from long-term Arctic acoustic recordings |journal=Polar Biology |language=en |volume=45 |issue=3 |pages=449–463 |bibcode=2022PoBio..45..449J |doi=10.1007/s00300-022-03008-5 |issn=1432-2056 |s2cid=246176509}}</ref>

=== Longevity and mortality factors ===
[[File:A polar bear (Ursus maritimus) scavenging a narwhal whale (Monodon monoceros) carcass - journal.pone.0060797.g001-A.png|thumb|A polar bear [[scavenging]] a narwhal carcass|alt=Polar bear feeding/scavenging on a beached narwhal carcass.]]
Age determination techniques using the number of [[periosteum]] layers in the [[lower jaw]] reveal that narwhals live an average of 50 years, though techniques using [[amino acid dating]] from the [[Lens (vertebrate anatomy)|lens]] of the eyes suggest that female narwhals can reach 115{{Nbsp}}±{{Nbsp}}10 years and male narwhals can live to 84{{Nbsp}}±{{Nbsp}}9 years.<ref>{{Cite journal |last1=Garde |first1=Eva |last2=Heide-Jørgensen |first2=Mads Peter |last3=Hansen |first3=Steen H. |last4=Nachman |first4=Gösta |last5=Forchhammer |first5=Mads C. |date=28 February 2007 |title=Age-specific growth and remarkable longevity in narwhals (''Monodon monoceros'') from West Greenland as estimated by aspartic acid racemization |journal=Journal of Mammalogy |volume=88 |issue=1 |pages=49–58 |doi=10.1644/06-mamm-a-056r.1 |issn=0022-2372}}</ref>

Death by [[suffocation]] often occurs when narwhals fail to migrate before the [[Climate change in the Arctic|Arctic freezes over]] in late autumn. This is known as "sea-ice entrapment".<ref name="Macdonald" /><ref name=":7">{{Cite journal |last1=Laidre |first1=Kristin |last2=Heide-Jørgensen |first2=Mads Peter |last3=Stern |first3=Harry |last4=Richard |first4=Pierre |date=1 January 2012 |title=Unusual narwhal sea ice entrapments and delayed autumn freeze-up trends |journal=Polar Biology |language=en |volume=35 |issue=1 |pages=149–154 |bibcode=2012PoBio..35..149L |doi=10.1007/s00300-011-1036-8 |issn=1432-2056 |s2cid=253807718}}</ref> Narwhals drown if open water is no longer accessible and ice is too thick for them to break through. Breathing holes in ice may be up to {{convert|1450|m|ft|-1|abbr=on}} apart, which limits the use of foraging grounds. These holes must be at least {{convert|0.5|m|ft|abbr=on}} wide to allow an adult whale to breathe.<ref name=":8">{{Cite journal |last1=Williams |first1=Terrie M. |last2=Noren |first2=Shawn R. |last3=Glenn |first3=Mike |date=April 2011 |title=Extreme physiological adaptations as predictors of climate-change sensitivity in the narwhal (''Monodon monoceros'') |url=https://onlinelibrary.wiley.com/doi/10.1111/j.1748-7692.2010.00408.x |journal=Marine Mammal Science |language=en |volume=27 |issue=2 |pages=334–349 |bibcode=2011MMamS..27..334W |doi=10.1111/j.1748-7692.2010.00408.x |issn=0824-0469|url-access=subscription }}</ref> Narwhals also die of [[starvation]] from entrapment events.<ref name=":21" />

In 1914{{endash}}1915, around 1,000 narwhal carcasses were discovered after entrapment events, most occurring in areas such as [[Disko Bay]] in [[West Greenland]].<ref>{{Cite journal |last=Porsild |first=Morten P. |date=1918 |title=On 'savssats': a crowding of Arctic animals at holes in the sea ice |journal=Geographical Review |volume=6 |issue=3 |pages=215–228 |bibcode=1918GeoRv...6..215P |doi=10.2307/207815 |issn=0016-7428 |jstor=207815}}</ref> Several cases of sea entrapment were recorded in 2008–2010, during the Arctic winter, including in some places where such events had never been recorded before.<ref name=":7" /> This suggests later departure dates from summering grounds. Wind and currents move sea ice from adjacent locations to Greenland, leading to fluctuations in concentration. Due to their tendency of returning to the same areas, changes in weather and ice conditions are not always associated with narwhal movement toward open water. It is currently unclear to what extent sea ice changes pose a danger to narwhals.<ref name=":18" /><ref name=":7" /><ref>{{Cite book |last1=Macdonald |first1=David Whyte |url=https://books.google.com/books?id=rdRFAAAAYAAJ |title=Mammals of Britain & Europe |last2=Barrett |first2=Priscilla |date=1993 |publisher=HarperCollins |isbn=978-0-00-219779-3 |page=173 |language=en}}</ref>

Narwhals are preyed upon by [[polar bear]]s and [[orca]]s. In some instances, the former have been recorded waiting at breathing holes for young narwhals, while the latter were observed surrounding and killing entire narwhal pods.<ref name="Macdonald" /><ref>{{Cite book |url=https://books.google.com/books?id=2rkHQpToi9sC&q=narwhals+attacked+by+polar+bears&pg=PA929 |title=Encyclopedia of Marine Mammals |publisher=Academic Press |year=2009 |isbn=978-0-08-091993-5 |editor-last=Perrin, William F. |pages=929–930 |access-date=18 November 2020 |editor-last2=Wursig, Bernd |editor-last3=Thewissen, J. G. M. 'Hans' |archive-url=https://web.archive.org/web/20240128092123/https://books.google.com/books?id=2rkHQpToi9sC&q=narwhals+attacked+by+polar+bears&pg=PA929#v=snippet&q=narwhals%20attacked%20by%20polar%20bears&f=false |archive-date=28 January 2024 |url-status=live}}</ref><ref>{{Cite journal |last1=Ferguson |first1=Steven H. |last2=Higdon |first2=Jeff W. |last3=Westdal |first3=Kristin H. |date=30 January 2012 |title=Prey items and predation behavior of killer whales (''Orcinus orca'') in Nunavut, Canada based on Inuit hunter interviews |journal=Aquatic Biosystems |volume=8 |issue=1 |page=3 |bibcode=2012AqBio...8....3F |doi=10.1186/2046-9063-8-3 |issn=2046-9063 |pmc=3310332 |pmid=22520955 |doi-access=free}}</ref><ref>{{Cite web |date=19 November 2014 |title=Invasion of the killer whales: killer whales attack pod of narwhal |url=https://www.pbs.org/wnet/nature/invasion-killer-whales-killer-whales-attack-pod-narwhals/11165/ |url-status=live |archive-url=https://web.archive.org/web/20161022071130/http://www.pbs.org/wnet/nature/invasion-killer-whales-killer-whales-attack-pod-narwhals/11165/ |archive-date=22 October 2016 |access-date=23 October 2016 |publisher=Public Broadcasting System}}</ref> To escape predators such as orcas, narwhals may use prolonged submersion to hide under [[ice floe]]s rather than relying on speed.<ref name=":8" />

Researchers found bacteria of the ''[[Brucella]]'' genus in the bloodstreams of numerous narwhals throughout the course of a 19-year study. They were also recorded with [[whale lice]] species such as ''[[Cyamus monodontis]]'' and ''[[Cyamus nodosus]]''. Other [[pathogen]]s that affect narwhals include ''[[Toxoplasma gondii]]'', [[morbillivirus]], and [[papillomavirus]].<ref>{{Cite journal |last1=Barratclough |first1=Ashley |last2=Ferguson |first2=Steven H. |last3=Lydersen |first3=Christian |last4=Thomas |first4=Peter O. |last5=Kovacs |first5=Kit M. |date=July 2023 |title=A review of circumpolar Arctic marine mammal health—a call to action in a time of rapid environmental change |journal=Pathogens |language=en |volume=12 |issue=7 |page=937 |doi=10.3390/pathogens12070937 |issn=2076-0817 |pmc=10385039 |pmid=37513784 |doi-access=free}}</ref> In 2018, a female narwhal was recorded with an [[alphaherpesvirus]] in her system.<ref>{{Cite journal |last1=Nielsen |first1=Ole |last2=Rodrigues |first2=Thaís C. S. |last3=Marcoux |first3=Marianne |last4=Béland |first4=Karine |last5=Subramaniam |first5=Kuttichantran |last6=Lair |first6=Stéphane |last7=Hussey |first7=Nigel E. |last8=Waltzek |first8=Thomas B. |date=6 July 2023 |title=Alphaherpesvirus infection in a free-ranging narwhal (''Monodon monoceros'') from Arctic Canada |url=https://www.int-res.com/abstracts/dao/v154/p131-139/ |journal=Diseases of Aquatic Organisms |language=en |volume=154 |pages=131–139 |doi=10.3354/dao03732 |issn=0177-5103 |pmid=37410432 |doi-access=free}}</ref>

== Conservation ==
The narwhal is listed as a species of [[least concern]] by the [[IUCN Red List]]. As of 2017, the global population is estimated to be 123,000 mature individuals out of a total of 170,000. There were about 12,000 narwhals in Northern Hudson Bay in 2011, and around 49,000 near [[Somerset Island (Nunavut)|Somerset Island]] in 2013. There are approximately 35,000 in [[Admiralty Inlet]], 10,000 in Eclipse Sound, 17,000 in [[Baffin Bay|Eastern Baffin Bay]], and 12,000 in [[Jones Sound]]. Population numbers in [[Smith Sound]], [[Inglefield Bredning]] and [[Melville Bay]] are 16,000, 8,000 and 3,000, respectively. There are roughly 800 narwhals in the waters off Svalbard.<ref name="IUCN2017" />

In the 1972 [[Marine Mammal Protection Act]], the United States banned imports of products made from narwhal parts.<ref name="IUCN2017" /> They are listed on Appendix II of the [[Convention on International Trade in Endangered Species of Wild Fauna and Flora]] (CITES) and [[Convention on the Conservation of Migratory Species of Wild Animals]] (CMS). These committees restrict international trading of live animals and their body parts, as well as implementing sustainable action plans.<ref name="IUCN2017" /><ref name="CITES" /><ref>{{Cite web |title=Fact sheet narwhal and climate change{{!}} CITES |url=https://www.cms.int/sites/default/files/publication/fact_sheet_narwhal_climate_change.pdf |url-status=live |archive-url=https://web.archive.org/web/20240126013159/https://www.cms.int/sites/default/files/publication/fact_sheet_narwhal_climate_change.pdf |archive-date=26 January 2024 |access-date=21 January 2024 |website=cms.int}}</ref> The species is classified as special concern under the [[Committee on the Status of Endangered Wildlife in Canada]] (COSEWIC), which aims to classify the risk levels of species in the country.<ref name=":3" /><ref>{{Cite journal |last1=Lukey |first1=James R. |last2=Crawford |first2=Stephen S. |date=June 2009 |title=Consistency of COSEWIC species at risk designations: freshwater fishes as a case study |url=http://www.nrcresearchpress.com/doi/10.1139/F09-054 |journal=Canadian Journal of Fisheries and Aquatic Sciences |language=en |volume=66 |issue=6 |pages=959–971 |doi=10.1139/F09-054 |bibcode=2009CJFAS..66..959L |issn=0706-652X|url-access=subscription }}</ref>

In 2025 the United Kingdom protected narwhals under the Ivory Act, which forbids trade in teeth and tusks except for "artistic and cultural artifacts."<ref name="ivory">{{Cite web |date=2025-01-28 |title=Ivory Act protections come into force for four more species |url=https://www.gov.uk/government/news/ivory-act-protections-come-into-force-for-four-more-species |access-date=2025-02-05 |website=GOV.UK |language=en}}</ref><ref name="ivbbvc">{{Cite web |date=2025-01-28 |title=UK Ivory Act: Ban extended to protect hippos and some whales |url=https://www.bbc.co.uk/newsround/articles/c17e9jxyq4no |access-date=2025-02-05 |website=BBC Newsround |language=en-GB}}</ref>

=== Threats ===

[[File:Belugas+Narwhals.png|thumb|Beluga and narwhal catches (1954–2014)|alt=Data showing the number of caught belugas and narwhals from 1954 to 2014. Belugas were reported from the US, Russia, Canada and Greenland, while narwhals were recorded from Canada and Russia.|upright=1.4]]

Narwhals are hunted for their skin, [[whale meat|meat]], teeth, tusks and [[Scrimshaw|carved vertebrae]], which are commercially traded. About 1,000 narwhals are killed per year: 600 in Canada and 400 in Greenland. Canadian catches were steady at this level in the 1970s, dropped to 300–400 per year in the late 1980s and 1990s and have risen again since 1999. Greenland caught more, 700–900 per year, in the 1980s and 1990s.<ref>{{Citation |last=Witting |first=Lars |title=Meta population modelling of narwhals in East Canada and West Greenland – 2017 |date=10 April 2017 |url=https://www.biorxiv.org/content/10.1101/059691v4 |access-date=14 February 2024 |language=en |doi=10.1101/059691 |s2cid=89062294}}</ref>

In Canada and Greenland, Narwhal tusks are sold both carved and uncarved.<ref name="hoover" /><ref>{{Cite news |last=Greenfieldboyce, Nell |date=19 August 2009 |title=Inuit hunters help scientists track narwhals |url=https://www.npr.org/2009/08/19/111980557/inuit-hunters-help-scientists-track-narwhals |url-status=live |archive-url=https://web.archive.org/web/20161024220450/http://www.npr.org/2009/08/19/111980557/inuit-hunters-help-scientists-track-narwhals |archive-date=24 October 2016 |access-date=24 October 2016 |work=NPR.org |publisher=National Public Radio}}</ref><ref name=":9">{{Cite journal |last=Heide-Jørgensen |first=Mads P. |date=22 April 1994 |title=Distribution, exploitation and population status of white whales (''Delphinapterus leucas'') and narwhals (''Monodon monoceros'') in West Greenland |url=https://tidsskrift.dk/meddrgroenland_biosci/article/view/142541 |journal=Meddelelser om Grønland, Bioscience |language=en |volume=39 |pages=135–149 |doi=10.7146/mogbiosci.v39.142541 |issn=0106-1054}}</ref> Per hunted narwhal, an average of one to two vertebrae and teeth are sold.<ref name="hoover" /> In Greenland, the skin ({{lang|iu|[[muktuk]]}}) is sold commercially to [[Fish factory|fish factories]],<ref name=":9" /> and in Canada to other communities.<ref name="hoover" /> Based on an analysis of 2007 narwhal hunts in Hudson Bay, a 2013 paper estimated that gross revenue per narwhal was {{CAD|6542}} (US${{To USD round|6542|CAN|year=2007}}). Hunts receive [[subsidies]], but they continue mainly to support tradition, rather than for profit. Economic analysis noted that [[whale watching]] may be an alternate source of revenue.<ref name="hoover">{{Cite journal |last1=Hoover |first1=C. |last2=Bailey |first2=M. L. |last3=Higdon |first3=J. |last4=Ferguson |first4=S. H. |last5=Sumaila |first5=R. |date=2013 |title=Estimating the economic value of narwhal and beluga hunts in Hudson Bay, Nunavut |url=https://library.wur.nl/WebQuery/wurpubs/437695 |journal=Arctic |publisher=Arctic Institute of North America |volume=66 |issue=1 |pages=1–16 |doi=10.14430/arctic4261 |issn=0004-0843}}</ref>

As narwhals grow, [[bioaccumulation]] of heavy metals takes place within their bodies.<ref name=":5">{{Cite journal |last1=Wagemann |first1=R. |last2=Snow |first2=N. B. |last3=Lutz |first3=A. |last4=Scott |first4=D. P. |date=9 December 1983 |title=Heavy metals in tissues and organs of the narwhal (''Monodon monoceros'') |url=http://www.nrcresearchpress.com/doi/10.1139/f83-326 |journal=Canadian Journal of Fisheries and Aquatic Sciences |language=en |volume=40 |issue=S2 |pages=s206–s214 |doi=10.1139/f83-326 |bibcode=1983CJFAS..40S.206W |issn=0706-652X|url-access=subscription }}</ref> It is thought that [[ocean pollution|pollution in the ocean]] is the primary cause of bioaccumulation in marine mammals; this may lead to health problems for the narwhal population.<ref>{{Citation |last1=Bouquegneau |first1=Krishna Das |title=Heavy metals in marine mammals |date=2003 |work=Toxicology of Marine Mammals |pages=147–179 |url=https://www.taylorfrancis.com/chapters/edit/10.1201/9780203165577-11/heavy-metals-marine-mammals-krishna-das-virginie-debacker-st%C3%A9phane-pillet-jean-marie-bouquegneau |access-date=4 February 2024 |publisher=CRC Press |doi=10.1201/9780203165577-11 |isbn=978-0-429-21746-3 |hdl=2268/3680 |last2=Debacker |first2=Virginie |last3=Pillet |first3=Stéphane Jean-Marie |hdl-access=free}}</ref> When bioaccumulating, numerous metals appear in the blubber, liver, kidney and musculature. A study found that the blubber was nearly devoid of these metals, whereas the liver and kidneys had a dense concentration of them. Relative to the liver, the kidney has a greater concentration of [[zinc]] and [[cadmium]], while [[lead]], [[copper]] and [[mercury (metal)|mercury]] were not nearly as abundant. Individuals of different weight and sex showed differences in the concentration of metals in their organs.<ref>{{Cite journal |last1=Dietz |first1=R. |last2=Riget |first2=F. |last3=Hobson |first3=K. |last4=Heidejorgensen |first4=M. |last5=Moller |first5=P. |last6=Cleemann |first6=M. |last7=Deboer |first7=J. |last8=Glasius |first8=M. |date=20 September 2004 |title=Regional and inter annual patterns of heavy metals, organochlorines and stable isotopes in narwhals (''Monodon monoceros'') from West Greenland |journal=Science of the Total Environment |volume=331 |issue=1–3 |pages=83–105 |bibcode=2004ScTEn.331...83D |doi=10.1016/j.scitotenv.2004.03.041 |issn=0048-9697 |pmid=15325143}}</ref>

Narwhals are one of the Arctic marine mammals most vulnerable to [[climate change]] due to sea ice decline,<ref name="Laidre2008" /> especially in their northern wintering grounds such as the Baffin Bay and Davis Strait regions. Satellite data collected from these areas shows the amount of sea ice has been markedly reduced from what it was previously.<ref name=":10">{{Cite journal |last1=Laidre |first1=Kristin L. |last2=Heide-Jørgensen |first2=Mads Peter |date=10 February 2011 |title=Life in the lead: extreme densities of narwhals (''Monodon monoceros'') in the offshore pack ice |url=https://www.int-res.com/abstracts/meps/v423/p269-278/ |journal=Marine Ecology Progress Series |language=en |volume=423 |pages=269–278 |bibcode=2011MEPS..423..269L |doi=10.3354/meps08941 |issn=0171-8630}}</ref> It is thought that narwhals' foraging ranges reflect patterns they acquired early in life, which improves their capacity to obtain the food supplies they need for the winter. This strategy focuses on strong [[site fidelity]] rather than individual-level responses to local prey distribution, resulting in focal foraging areas during the winter. As such, despite changing conditions, narwhals will continue to return to the same areas during migration.<ref name=":10" />

Reduction in sea ice has possibly led to an increased exposure to predation. In 2002, hunters in [[Siorapaluk]] experienced an increase in the number of caught narwhals, but this increase did not seem to be linked to enhanced endeavour,<ref>{{Cite journal |last1=Kovacs |first1=Kit M. |last2=Lydersen |first2=Christian |last3=Overland |first3=James E. |last4=Moore |first4=Sue E. |date=1 March 2011 |title=Impacts of changing sea-ice conditions on Arctic marine mammals |journal=Marine Biodiversity |language=en |volume=41 |issue=1 |pages=181–194 |bibcode=2011MarBd..41..181K |doi=10.1007/s12526-010-0061-0 |issn=1867-1624}}</ref> implying that climate change may be making the narwhal more vulnerable to hunting. Scientists recommend assessing population numbers, assigning sustainable [[catch share|quotas]], and ensuring local acceptance of sustainable development. [[Seismic survey]]s associated with [[oil exploration]] disrupt the narwhal's normal migration patterns. These disturbed migrations may also be associated with increased sea ice entrapment.<ref>{{Cite journal |last1=Heide-Jørgensen |first1=Mads Peter |last2=Hansen |first2=Rikke Guldborg |last3=Westdal |first3=Kristin |last4=Reeves |first4=Randall R. |last5=Mosbech |first5=Anders |date=February 2013 |title=Narwhals and seismic exploration: is seismic noise increasing the risk of ice entrapments? |journal=Biological Conservation |volume=158 |pages=50–54 |bibcode=2013BCons.158...50H |doi=10.1016/j.biocon.2012.08.005 |issn=0006-3207 |doi-access=free}}</ref>

== Relationship with humans ==
[[File:Children of the Arctic (1903) (14766096922).jpg|thumb|left|Hunter posing next to a narwhal head (1903)|alt=An Inuit man holding the head of a dead narwhal in the Arctic.]]
Narwhals have coexisted alongside [[circumpolar peoples]] for millennia.<ref name="WinterWhales" /> Their long, distinctive tusks were often held with fascination throughout human history.<ref name="COSEWIC4">{{Cite web |last=Canada |first=Service |date=13 October 2015 |title=Narwhal (Monodon monoceros) COSEWIC assessment and status report |url=https://www.canada.ca/errors/404.html |access-date=4 July 2024 |website=www.canada.ca |archive-date=2 September 2024 |archive-url=https://web.archive.org/web/20240902234055/https://www.canada.ca/errors/404.html }}</ref> These tusks were prized for their supposed healing powers, and were worn on staffs and thrones. Depictions of narwhal tusks in works of art such as ''[[The Lady and the Unicorn]]'' have found a prevalent place in [[The arts|human arts]].<ref name=":16" /><ref name=":17">{{Cite book |last=Wexler |first=Philip |url=https://books.google.com/books?id=ttB1DQAAQBAJ&dq=info:mS3yEjef_cEJ:scholar.google.com/&pg=PA101 |title=Toxicology in the Middle Ages and Renaissance |date=2017 |publisher=Academic Press |isbn=978-0-12-809559-1 |pages=101–102 |language=en}}</ref>

=== Inuit ===

Narwhals have been hunted by [[Inuit]] to the same extent as other sea mammals, such as [[Pinniped|seals]] and [[whale]]s. Almost all parts of the narwhal{{emdash}}the meat, skin, blubber and organs{{emdash}}are consumed. {{Lang|iu|Muktuk}}, the raw skin and attached blubber, is considered a delicacy. As a custom, one or two vertebrae per animal are used for tools and [[Inuit art|art]].<ref name="WinterWhales" /><ref name="hoover" /> The skin is an important source of [[vitamin C]], which is otherwise difficult to obtain in the Arctic Circle. In some places in Greenland, such as [[Qaanaaq]], traditional hunting methods are used and whales are [[harpoon]]ed from handmade [[kayaks]]. In other parts of Greenland and Northern Canada, [[motorboat|high-speed boat]]s and [[hunting rifle]]s are used.<ref name="WinterWhales" />

In [[Inuit religion|Inuit legend]], the narwhal's tusk was created when a woman with harpoon rope tied around her waist was dragged into the ocean after the harpoon had stuck into a large narwhal. She was then [[shapeshifting|transformed]] into a narwhal; her hair, which she was wearing in a [[Braid (hairstyle)|twisted knot]], became the spiralling narwhal tusk.<ref>{{Cite book |last1=Bastian |first1=Dawn Elaine |url=https://books.google.com/books?id=IsyQu1kDK-kC |title=Handbook of Native American Mythology |last2=Mitchell |first2=Judy K. |date=2004 |publisher=Bloomsbury Academic |isbn=1-85109-533-0 |pages=54–55 |language=en}}</ref>

=== Tusk trade ===

[[File:Narwhal Goblet (30061080057).jpg|thumb|A [[goblet]] made from narwhal tusk in [[Milan]], Italy|alt=A goblet composed of narwhal tusk from Milan, Italy. The goblet is covered with jewels, has snake-shaped handles and a depiction of a woman at the top.]]

In Europe, narwhal tusks were highly sought after for centuries. This stems from a medieval belief that narwhal tusks were the [[Unicorn horn|horns]] of the legendary [[unicorn]].<ref>{{Cite journal |last1=Dugmore |first1=Andrew J. |last2=Keller |first2=Christian |last3=McGovern |first3=Thomas H. |date=6 February 2007 |title=Norse Greenland settlement: reflections on climate change, trade, and the contrasting fates of human settlements in the North Atlantic islands |url=https://aa.uwpress.org/content/44/1/12 |journal=Arctic Anthropology |language=en |volume=44 |issue=1 |pages=12–36 |doi=10.1353/arc.2011.0038 |issn=0066-6939 |pmid=21847839 |s2cid=10030083|url-access=subscription }}</ref><ref name=":12">{{Cite journal |last=Pluskowski |first=Aleksander |date=January 2004 |title=Narwhals or unicorns? Exotic animals as material culture in medieval Europe |url=https://www.cambridge.org/core/journals/european-journal-of-archaeology/article/abs/narwhals-or-unicorns-exotic-animals-as-material-culture-in-medieval-europe/23DAD0724CE1D3C55A34950AE30E6BDF |journal=European Journal of Archaeology |language=en |volume=7 |issue=3 |pages=291–313 |doi=10.1177/1461957104056505 |issn=1461-9571 |s2cid=162878182|url-access=subscription }}</ref><ref name="Daston">{{Cite book |last1=Daston |first1=Lorraine |title=Wonders and the Order of Nature, 1150–1750 |last2=Park |first2=Katharine |date=2001 |publisher=Zone Books |isbn=0-942299-91-4}}</ref> Considered to have magical properties, narwhal tusks were used to counter poisoning, and all sorts of diseases such as [[measles]] and [[rubella]].<ref name=":17" /><ref>{{Cite book |last=Rochelandet |first=Brigitte |url=https://books.google.com/books?id=NU9dAVCb2UsC |title=Monstres et merveilles de Franche-Comté: fées, fantômes et dragons |date=2003 |publisher=Editions Cabédita |isbn=978-2-88295-400-8 |page=131 |language=fr}}</ref><ref>{{Cite journal |last=Robertson |first=W. G. Aitchison |date=1926 |title=The use of the unicorn's horn, coral and stones in medicine |journal=Annals of Medical History |volume=8 |issue=3 |pages=240–248 |issn=0743-3131 |pmc=7946245 |pmid=33944492}}</ref> The rise of modern science towards the end of the 17th century led to a decreased belief in [[Magic (supernatural)|magic]] and [[alchemy]]. After the unicorn notion was scientifically refuted, narwhal tusks were rarely employed for magical purposes.<ref>{{Cite journal |last=Spary |first=E C |date=2019 |title=On the ironic specimen of the unicorn horn in enlightened cabinets |journal=Journal of Social History |volume=52 |issue=4 |pages=1033–1060 |doi=10.1093/jsh/shz005 |issn=1527-1897 |doi-access=free}}</ref><ref>{{Cite journal |last=Schoenberger |first=Guido |date=1951 |title=A goblet of unicorn horn |journal=The Metropolitan Museum of Art Bulletin |volume=9 |issue=10 |pages=284–288 |doi=10.2307/3258091 |issn=0026-1521 |jstor=3258091}}</ref>

[[Vikings]] and [[Norse settlement of North America#Norse Greenland|Greenland Norse]] likely began the trade of narwhal tusks, which, via European channels, would later reach markets in the [[Middle East]] and [[East Asia]]. It is unclear if they hunted the narwhals themselves or mainly recovered the tusks from the corpses of animals killed by orcas.<ref>{{Cite journal |last=Dectot |first=Xavier |date=October 2018 |title=When ivory came from the seas. On some traits of the trade of raw and carved sea-mammal ivories in the Middle Ages |url=https://bioone.org/journals/anthropozoologica/volume-53/issue-1/anthropozoologica2018v53a14/When-ivory-came-from-the-seas-On-some-traits-of/10.5252/anthropozoologica2018v53a14.full |journal=Anthropozoologica |volume=53 |issue=1 |pages=159–174 |doi=10.5252/anthropozoologica2018v53a14 |issn=0761-3032 |s2cid=135259639|url-access=subscription }}</ref><ref>{{Cite journal |last=Schmölcke |first=Ulrich |date=December 2022 |title=What about exotic species? Significance of remains of strange and alien animals in the Baltic Sea region, focusing on the period from the Viking Age to high medieval times (800–1300 CE) |journal=Heritage |language=en |volume=5 |issue=4 |pages=3864–3880 |doi=10.3390/heritage5040199 |issn=2571-9408 |doi-access=free}}</ref> Narwhal tusks were given as state gifts to kings and queens throughout medieval Europe, with the price of narwhal tusks said to have been a couple of hundred times greater than their weight in [[gold]] during the 18th and 19th centuries.<ref name=":16">{{Cite journal |last=Nweeia |first=Martin T. |date=15 February 2024 |title=Biology and cultural importance of the narwhal |journal=Annual Review of Animal Biosciences |volume=12 |pages=187–208 |doi=10.1146/annurev-animal-021122-112307 |issn=2165-8110 |pmid=38358838 |doi-access=free}}</ref><ref name=":12" /> [[Ivan the Terrible]] had a jewellery-covered narwhal tusk on his deathbed,<ref name=":12" /> while [[Elizabeth I]] received a narwhal tusk allegedly valued at £10,000 [[pounds sterling]] from the [[privateer]] [[Martin Frobisher]].<ref>{{Cite book |last=Sherman |first=Josepha |url=https://books.google.com/books?id=n2-sBwAAQBAJ&pg=PA476 |title=Storytelling: An Encyclopedia of Mythology and Folklore |date=2015 |publisher=Routledge |isbn=978-1-317-45938-5 |page=476 |access-date=18 September 2023 |archive-url=https://web.archive.org/web/20230928025222/https://books.google.com/books?id=n2-sBwAAQBAJ&pg=PA476 |archive-date=28 September 2023 |url-status=live}}</ref> Both items were staples in [[cabinets of curiosities]].<ref>{{Citation |title=Ice and Eskimos: Dealing With a New Otherness |date=2014 |work=The Quest for the Northwest Passage: Knowledge, Nation and Empire, 1576–1806 |editor-last=Regard |editor-first=Frédéric |url=https://www.cambridge.org/core/books/quest-for-the-northwest-passage/ice-and-eskimos-dealing-with-a-new-otherness/661ABBD6CC09480358D68E67B25708D3 |access-date=13 February 2024 |publisher=Pickering & Chatto |isbn=978-1-84893-270-8}}</ref><ref>{{Cite journal |last=Duffin |first=Christopher J. |date=January 2017 |title='Fish', fossil and fake: medicinal unicorn horn |url=https://www.lyellcollection.org/doi/10.1144/SP452.16 |journal=Geological Society, London, Special Publications |volume=452 |issue=1 |pages=211–259 |bibcode=2017GSLSP.452..211D |doi=10.1144/SP452.16 |issn=0305-8719 |s2cid=133366872|url-access=subscription }}</ref>{{Clear}}

== References ==
{{Reflist}}

== Further reading ==
{{Refbegin}}
*{{Cite magazine |last1=Ford |first1=John |last2=Ford |first2=Deborah |date=March 1986 |title=Narwhal: unicorn of the Arctic seas |magazine=[[National Geographic]] |pages=354–363 |volume=169 |issue=3 |issn=0027-9358 |oclc=643483454 |ref=none}}
*{{Cite web |last=Groc |first=Isabelle |date=12 February 2014 |title=The world's weirdest whale: hunt for the sea unicorn |url=https://www.newscientist.com/article/mg22129564-500-the-worlds-weirdest-whale-hunt-for-the-sea-unicorn/ |access-date=10 February 2024 |website=New Scientist |language=en-US |ref=none}}
{{Refend}}

{{Cetacea|O.}}
{{Odontoceti|D.}}{{Portal bar|Cetaceans|Mammals|Marine life}}{{Taxonbar |from=Q159426}}
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[[Category:Mammals described in 1758]]
[[Category:Cetaceans of the Arctic Ocean]]
[[Category:Mammals of Canada]]
[[Category:Mammals of Greenland]]
[[Category:Mammals of Russia]]
[[Category:Monodontidae]]
[[Category:Articles containing video clips]]
[[Category:Unicorns]]
[[Category:Animal taxa named by Carl Linnaeus]]
[[Category:Fauna of the Holarctic realm]]
[[Category:Fauna of Northern Canada]]