Thenarwhal (Monodon monoceros) is aspecies oftoothed whale native to theArctic. It is the only member of thegenusMonodon and one of two living representatives of the familyMonodontidae. The narwhal is a stocky cetacean with a relatively blunt snout, a largemelon, and a shallow ridge in place of adorsal fin. Males of this species have a large (1.5–3.0 m (4 ft 11 in – 9 ft 10 in)) longtusk, which is a protruding leftcanine thought to function as a weapon, a tool for feeding, inattracting mates or sensing water salinity. Specially adaptedslow-twitch muscles, 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 relatedbeluga whale, and the animals are known tointerbreed.
Narwhals inhabit theArctic waters of Canada, Greenland and Russia. Every year, theymigrate to ice-free summering grounds, usually in shallow waters, and oftenreturn to the same sites in subsequent years. Their diet mainly consists ofpolar andArctic cod,Greenland halibut,cuttlefish,shrimp, andarmhook squid. Diving to depths of up to 2,370 m (7,780 ft), the narwhal is among the deepest-divingcetaceans. 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 offshorepack 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.
The narwhal was scientifically described byCarl Linnaeus in his 1758 publicationSystema Naturae.[5] The word "narwhal" comes from theOld Norsenárhval, 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.[6][7] The scientific name,Monodon monoceros, is derived fromAncient Greek, meaning 'single-tooth single-horn'.[8]
The narwhal is most closely related to thebeluga whale (Delphinapterus leucas). Together, these two species comprise the onlyextant members of the familyMonodontidae. Monodontids are distinguished by their pronouncedmelons (acoustic sensory organs), shortsnouts and the absence of a truedorsal fin.[9][10]
Although the narwhal and beluga are classified as separate genera, there is some evidence ofinterbreeding 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 ahybrid between the two species (a 'narluga');[11] this was confirmed by a 2019DNA analysis.[12] Whether the hybrid itselfcould breed remains unknown.[11][13]
Evolution
Results of a genetic study reveal thatporpoises and monodontids are closely related, forming a separateclade which diverged from otherdolphins about 11million years ago (mya).[14] 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 besister taxa.[15] A laterphylogenetic study conducted in 2020 suggested that the narwhal split from the beluga whale around 4.98 mya, based on data frommitochondrial DNA.[16]
The fossil speciesCasatia thermophila ofearly Pliocene central Italy was described as a possible narwhal ancestor when it was discovered in 2019.Bohaskaia,Denebola andHaborodelphis are other extinct genera known from thePliocene of the United States.[17][18][19] 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.[17][18]
The followingphylogenetic tree is based on a 2019 study of the family Monodontidae.[17]
The narwhal has a robust body with a short, blunt snout, small upcurved flippers, and convex to concave tail flukes. Adults measure 3.0 to 5.5 m (9.8 to 18.0 ft) in length and weigh 800 to 1,600 kg (1,800 to 3,500 lb).[20][21][22] Male narwhals attainsexual maturity at 12 to 20 years of age, reaching a length of 3.5 to 4.0 m (11.5 to 13.1 ft). Females reach sexual maturity at a younger age, between 8 and 9 years old, when they are about 3.4 m (11 ft) long.[23] On average, males are about 70 cm (28 in) longer and more than 75% heavier than females.[24]
The colouration of the narwhal consists of amottled pattern, with blackish-brown markings over a white background. At birth, the skin is light grey, and when sexually mature, white patches grow on thenavel andgenital slit;[7] such whitening occurs throughout life, resulting in aged narwhals being almost purely white.[22] Unlike most whales, the narwhal has a shallow dorsal ridge, rather than a dorsal fin, possibly anevolutionary adaptation to make swimming under ice easier or to facilitate rolling.[25] The neckvertebrae 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.[10] 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 reducingdrag caused by the tusk.[26]
Theskeletal muscles of narwhals are highly adapted for prolonged periods of deep-sea foraging. During such activities, oxygen is reserved in the muscles, which are typicallyslow-twitch, enabling greater endurance and manouverability.[27] Narwhals also have a comparatively high amount ofmyoglobin in their body, which helps to facilitate deeper dives.[28] It has a dense layer ofblubber, around 50 to 100 mm (2.0 to 3.9 in) thick. This fat accounts for a third of the body mass and helps insulate from cold ocean temperatures.[6][21][29]
Tusk and dentition
Narwhal tusk
The most conspicuous trait of male narwhals is a long, spiralled tusk, which is acanine tooth that projects from the left side of the upper jaw.[22][30] 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.[22] The tusk grows throughout the animal's life, reaching lengths of 1.5 to 3 m (4 ft 11 in to 9 ft 10 in).[31][32][33] It is hollow and weighs up to 7.45 kg (16.4 lb). Some males may grow two tusks, occurring when the right canine also protrudes through the lip.[33][34] Females rarely grow tusks: when they do, the tusks are typically smaller than those of males, with less noticeable spirals.[7][35]
Currentscientific consensus indicates that narwhal tusks aresecondary 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.[36] The tusk is also a highlyinnervatedsensory organ with millions ofnerve endings, allowing the narwhal to sense temperature variability in its surroundings.[30] These nerves may also be able to detect changes in particle concentration and water pressure.[37][38] 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.[37][38]Drone footage from August 2016 in Tremblay Sound,Nunavut, revealed that narwhals used their tusks to tap andstun smallArctic cod, making them easier to catch for feeding.[36][39] 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 withsexual selection.[36][40]
Alongside its tusk, the narwhal has a single pair of smallvestigial teeth that reside in opentooth sockets in the upper jaw. These teeth, which differ in form and composition, encircle the exposed tooth sockets laterally, posteriorly, and ventrally.[30][41] Vestigial teeth in male narwhals are commonly shed in thepalate. The varied morphology and anatomy of small teeth indicate a path of evolutionary obsolescence.[30][42]
Distribution
Pod of six narwhals
The narwhal is found in the Atlantic and Russian areas of theArctic Ocean. Individuals are commonly recorded in theCanadian Arctic Archipelago,[43][44] such as in the northern part ofHudson Bay, inHudson Strait, inBaffin Bay, off the east coast of Greenland and in a strip running east from the northern end of Greenland to eastern Russia (170° east). Land in this strip includesSvalbard,Franz Joseph Land andSevernaya Zemlya.[7] The northernmost sightings of narwhals occurred north of Franz Joseph Land, at about85° north.[7] There are an estimated 12,500 narwhals in the northern Hudson Bay, whereas around 140,000 reside in Baffin Bay.[45]
Migration
Narwhals exhibitseasonal migration, with a highfidelity 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 thickpack ice, surfacing in narrow fissures or in wider fractures known asleads.[7][46] As spring comes, these leads open up into channels and the narwhals return to the coastalbays.[47][48] Narwhals in Baffin Bay typically travel to northern Canada and Greenland between June and September. After this period, they travel about 1,700 kilometres (1,100 mi) south to theDavis Strait, and stay there until April.[45] During winter, narwhals from Canada and West Greenland regularly visit the pack ice of the Davis Strait and Baffin Bay along thecontinental slope which contains less than 5% open water and hosts a high density ofGreenland halibut.[49][7]
Behaviour and ecology
Narwhal tail fluke
Narwhals normallycongregate 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.[10][21][50] In the summer, several groups come together, forming larger aggregations which can contain 500 to over 1,000 individuals.[20][22] Male narwhals have been observed rubbing each other's tusks, a behaviour known as "tusking".[37][51]
When in their wintering waters, narwhals make some of the deepest dives recorded for cetaceans, diving to at least 800 m (2,620 ft) over 15 times per day, with many dives reaching 1,500 m (4,920 ft).[52][53] The greatest dive depth recorded is 2,370 m (7,780 ft).[52][54] 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.[52]
Diet
Narwhals have a restricted and specialised diet.[46][55] Due to the lack of well-developeddentition, narwhals are believed to feed by swimming close to prey andsucking them into the mouth.[56] A study of the stomach contents of 73 narwhals found Arctic cod (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 500 m (1,600 ft). The study also concluded that the size of prey did not differ between genders or age groups.[57] Other items found within narwhal stomach contents includewolffish,capelin,skate eggs and sometimes rocks.[20][46][49]
Narwhal diet varies between seasons. In winter, narwhals feed ondemersal prey, mostlyflatfish, 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.[57] Narwhals consume more food in the winter months than they do in summer.[46][49]
Breeding
Most female narwhals reproduce by the time they are six to eight years old.[6]Courtship andmating 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 averagegestation 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.[23][58][59] As with most marine mammals, only a single calf is born, averaging 1.5 m (4.9 ft) in length with white or light grey pigmentation.[60][61] Summer population surveys along different coastal inlets ofBaffin Island found that calf numbers varied from 0.05% of 35,000 inAdmiralty Inlet, to 5% of 10,000 total inEclipse Sound. These findings suggest that higher calf counts may reflect calving and nursery habitats in favourable inlets.[62]
Newborn calves begin their lives with a thin layer of blubber. The blubber thickens as theynurse their mother's milk, which is rich in fat; calves are dependent on milk for about 20 months.[20][63] This long lactation period gives calves time to learn the skills they will need to survive as they mature.[62][63] Narwhals are among the few animals that undergomenopause and live for decades after they have finished breeding. Females in this phase may continue to protect calves in the pod.[23][64] A 2024 study concluded that five species oftoothed 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.[64]
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 theblowhole.[65][66] The frequency of these sounds ranges from 0.3 to 125hertz, while those used forecholocation typically fall between 19 and 48 hertz.[67][68] Sounds are reflected off the sloping front of the skull and focused by the animal'smelon: a mass of fat which can be controlled through surrounding musculature.[66][69] Echolocation clicks are used for detecting prey and locating barriers at short distances.[66][70] Whistles and throbs are most commonly used to communicate with other pod members.[66][71] 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.[7][72] Other sounds produced by narwhals include trumpeting and "squeaking-door sounds".[6] 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.[73]
Age determination techniques using the number ofperiosteum layers in thelower jaw reveal that narwhals live an average of 50 years, though techniques usingamino acid dating from thelens of the eyes suggest that female narwhals can reach 115±10 years and male narwhals can live to 84±9 years.[74]
Death bysuffocation often occurs when narwhals fail to migrate before theArctic freezes over in late autumn. This is known as "sea-ice entrapment".[20][75] 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 1,450 m (4,760 ft) apart, which limits the use of foraging grounds. These holes must be at least 0.5 m (1.6 ft) wide to allow an adult whale to breathe.[28] Narwhals also die ofstarvation from entrapment events.[21]
In 1914–1915, around 1,000 narwhal carcasses were discovered after entrapment events, most occurring in areas such asDisko Bay inWest Greenland.[76] 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.[75] 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.[55][75][77]
Narwhals are preyed upon bypolar bears andorcas. 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.[20][78][79][80] To escape predators such as orcas, narwhals may use prolonged submersion to hide underice floes rather than relying on speed.[28]
The narwhal is listed as a species ofleast concern by theIUCN 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 nearSomerset Island in 2013. There are approximately 35,000 inAdmiralty Inlet, 10,000 in Eclipse Sound, 17,000 inEastern Baffin Bay, and 12,000 inJones Sound. Population numbers inSmith Sound,Inglefield Bredning andMelville Bay are 16,000, 8,000 and 3,000, respectively. There are roughly 800 narwhals in the waters off Svalbard.[3]
In 2025 the United Kingdom protected narwhals under the Ivory Act, which forbids trade in teeth and tusks except for "artistic and cultural artifacts."[85][86]
Threats
Beluga and narwhal catches (1954–2014)
Narwhals are hunted for their skin,meat, teeth, tusks andcarved 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.[87]
In Canada and Greenland, Narwhal tusks are sold both carved and uncarved.[88][89][90] Per hunted narwhal, an average of one to two vertebrae and teeth are sold.[88] In Greenland, the skin (muktuk) is sold commercially tofish factories,[90] and in Canada to other communities.[88] Based on an analysis of 2007 narwhal hunts in Hudson Bay, a 2013 paper estimated that gross revenue per narwhal wasCA$6,542 (US$6,091). Hunts receivesubsidies, but they continue mainly to support tradition, rather than for profit. Economic analysis noted thatwhale watching may be an alternate source of revenue.[88]
As narwhals grow,bioaccumulation of heavy metals takes place within their bodies.[91] It is thought thatpollution in the ocean is the primary cause of bioaccumulation in marine mammals; this may lead to health problems for the narwhal population.[92] 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 ofzinc andcadmium, whilelead,copper andmercury were not nearly as abundant. Individuals of different weight and sex showed differences in the concentration of metals in their organs.[93]
Narwhals are one of the Arctic marine mammals most vulnerable toclimate change due to sea ice decline,[47] 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.[94] 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 strongsite 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.[94]
Reduction in sea ice has possibly led to an increased exposure to predation. In 2002, hunters inSiorapaluk experienced an increase in the number of caught narwhals, but this increase did not seem to be linked to enhanced endeavour,[95] implying that climate change may be making the narwhal more vulnerable to hunting. Scientists recommend assessing population numbers, assigning sustainablequotas, and ensuring local acceptance of sustainable development.Seismic surveys associated withoil exploration disrupt the narwhal's normal migration patterns. These disturbed migrations may also be associated with increased sea ice entrapment.[96]
Relationship with humans
Hunter posing next to a narwhal head (1903)
Narwhals have coexisted alongsidecircumpolar peoples for millennia.[7] Their long, distinctive tusks were often held with fascination throughout human history.[97] 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 asThe Lady and the Unicorn have found a prevalent place inhuman arts.[98][99]
Inuit
Narwhals have been hunted byInuit to the same extent as other sea mammals, such asseals andwhales. Almost all parts of the narwhal—the meat, skin, blubber and organs—are consumed.Muktuk, the raw skin and attached blubber, is considered a delicacy. As a custom, one or two vertebrae per animal are used for tools andart.[7][88] The skin is an important source ofvitamin C, which is otherwise difficult to obtain in the Arctic Circle. In some places in Greenland, such asQaanaaq, traditional hunting methods are used and whales areharpooned from handmadekayaks. In other parts of Greenland and Northern Canada,high-speed boats andhunting rifles are used.[7]
InInuit 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 thentransformed into a narwhal; her hair, which she was wearing in atwisted knot, became the spiralling narwhal tusk.[100]
In Europe, narwhal tusks were highly sought after for centuries. This stems from a medieval belief that narwhal tusks were thehorns of the legendaryunicorn.[101][102][103] Considered to have magical properties, narwhal tusks were used to counter poisoning, and all sorts of diseases such asmeasles andrubella.[99][104][105] The rise of modern science towards the end of the 17th century led to a decreased belief inmagic andalchemy. After the unicorn notion was scientifically refuted, narwhal tusks were rarely employed for magical purposes.[106][107]
Vikings andGreenland Norse likely began the trade of narwhal tusks, which, via European channels, would later reach markets in theMiddle East andEast Asia. It is unclear if they hunted the narwhals themselves or mainly recovered the tusks from the corpses of animals killed by orcas.[108][109] 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 ingold during the 18th and 19th centuries.[98][102]Ivan the Terrible had a jewellery-covered narwhal tusk on his deathbed,[102] whileElizabeth I received a narwhal tusk allegedly valued at £10,000pounds sterling from theprivateerMartin Frobisher.[110] Both items were staples incabinets of curiosities.[111][112]
^Linnaeus, Carl (1758)."Monodon monoceros".Systema naturae per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata (in Latin). Stockholm: Lars Salvius. p. 75.
^abcdefghijkHeide-Jørgensen, M. P.; Laidre, K. L. (2006).Greenland's Winter Whales: The Beluga, the Narwhal and the Bowhead Whale. Ilinniusiorfik Undervisningsmiddelforlag, Nuuk, Greenland. pp. 100–125.ISBN87-7975-299-3.
^Webster, Noah (1880)."Narwhal".An American Dictionary of the English Language. G. & C. Merriam. p. 854.
^abcdefMacdonald, David Whyte; Barrett, Priscilla (2001).Mammals of Europe. Princeton University Press. p. 173.ISBN0-691-09160-9.Archived from the original on 28 January 2024. Retrieved27 January 2024.
^abcGarde, Eva; Hansen, Steen H.; Ditlevsen, Susanne; Tvermosegaard, Ketil Biering; Hansen, Johan; Harding, Karin C.; Heide-Jørgensen, Mads Peter (7 July 2015). "Life history parameters of narwhals (Monodon monoceros) from Greenland".Journal of Mammalogy.96 (4):866–879.doi:10.1093/jmammal/gyv110.ISSN0022-2372.
^Kingsley, Michael (October 1989). "Population dynamics of the narwhal Monodon monoceros: an initial assessement (Odontoceti: Monodontidae)".Journal of Zoology.219 (2):201–208.doi:10.1111/j.1469-7998.1989.tb02576.x.ISSN0952-8369.
^Pagano, Anthony M.; Williams, Terrie M. (15 February 2021). "Physiological consequences of Arctic sea ice loss on large marine carnivores: unique responses by polar bears and narwhals".Journal of Experimental Biology.224 (Suppl_1) jeb228049.Bibcode:2021JExpB.224B8049P.doi:10.1242/jeb.228049.ISSN0022-0949.PMID33627459.
^abcdNweeia, Martin T.; Eichmiller, Frederick C.; Hauschka, Peter V.; Donahue, Gretchen A.; Orr, Jack R.; Ferguson, Steven H.; Watt, Cortney A.; Mead, James G.; Potter, Charles W.; Dietz, Rune; Giuseppetti, Anthony A.; Black, Sandie R.; Trachtenberg, Alexander J.; Kuo, Winston P. (18 March 2014)."Sensory ability in the narwhal tooth organ system".The Anatomical Record.297 (4):599–617.doi:10.1002/ar.22886.ISSN1932-8486.PMID24639076.Archived from the original on 24 January 2024. Retrieved24 January 2024.
^abcLoch, Carolina; Fordyce, R. Ewan; Werth, Alexander (2023), Würsig, Bernd; Orbach, Dara N. (eds.), "Skulls, teeth, and sex",Sex in Cetaceans: Morphology, Behavior, and the Evolution of Sexual Strategies, Cham: Springer International Publishing, pp. 51–64,doi:10.1007/978-3-031-35651-3_3,ISBN978-3-031-35651-3
^abcBroad, William (13 December 2005)."It's sensitive. Really".The New York Times.Archived from the original on 28 January 2024. Retrieved22 February 2017.
^Nweeia, Martin T.; Eichmiller, Frederick C.; Hauschka, Peter V.; Tyler, Ethan; Mead, James G.; Potter, Charles W.; Angnatsiak, David P.; Richard, Pierre R.; Orr, Jack R.; Black, Sandie R. (30 March 2012). "Vestigial tooth anatomy and tusk nomenclature forMonodon Monoceros".The Anatomical Record.295 (6):1006–1016.doi:10.1002/ar.22449.ISSN1932-8486.PMID22467529.
^Heide-Jørgensen, M. P. (2018),"Narwhal:Monodon monoceros", in Würsig, Bernd; Thewissen, J. G. M.; Kovacs, Kit M. (eds.),Encyclopedia of Marine Mammals (Third Edition), Academic Press, pp. 627–631,ISBN978-0-12-804327-1,archived from the original on 20 January 2023, retrieved27 January 2024
^Davis, Randall W. (2019). "Appendix 3. Maximum Recorded Dive Depths and Durations for Marine Mammals".Marine Mammals. Adaptations for an Aquatic Life. Berlin/Heidelberg: Springer.ISBN978-3-319-98278-6.
^abFinley, K. J.; Gibb, E. J. (December 1982). "Summer diet of the narwhal (Monodon monoceros) in Pond Inlet, northern Baffin Island".Canadian Journal of Zoology.60 (12):3353–3363.Bibcode:1982CaJZ...60.3353F.doi:10.1139/z82-424.ISSN0008-4301.
^Würsig, Bernd; Rich, Jacquline; Orbach, Dara N. (2023), Würsig, Bernd; Orbach, Dara N. (eds.), "Sex and Behavior",Sex in Cetaceans: Morphology, Behavior, and the Evolution of Sexual Strategies, Cham: Springer International Publishing, pp. 1–27,doi:10.1007/978-3-031-35651-3_1,ISBN978-3-031-35651-3
^Mann, Janet (1 January 2009),"Parental Behavior", in Perrin, William F.; Würsig, Bernd; Thewissen, J. G. M. (eds.),Encyclopedia of Marine Mammals (Second Edition), London: Academic Press, pp. 830–836,ISBN978-0-12-373553-9, retrieved17 July 2024
^Jones, Joshua M.; Frasier, Kaitlin E.; Westdal, Kristin H.; Ootoowak, Alex J.; Wiggins, Sean M.; Hildebrand, John A. (1 March 2022). "Beluga (Delphinapterus leucas) and narwhal (Monodon monoceros) echolocation click detection and differentiation from long-term Arctic acoustic recordings".Polar Biology.45 (3):449–463.Bibcode:2022PoBio..45..449J.doi:10.1007/s00300-022-03008-5.ISSN1432-2056.S2CID246176509.
^Garde, Eva; Heide-Jørgensen, Mads Peter; Hansen, Steen H.; Nachman, Gösta; Forchhammer, Mads C. (28 February 2007). "Age-specific growth and remarkable longevity in narwhals (Monodon monoceros) from West Greenland as estimated by aspartic acid racemization".Journal of Mammalogy.88 (1):49–58.doi:10.1644/06-mamm-a-056r.1.ISSN0022-2372.
^Dietz, R.; Riget, F.; Hobson, K.; Heidejorgensen, M.; Moller, P.; Cleemann, M.; Deboer, J.; Glasius, M. (20 September 2004). "Regional and inter annual patterns of heavy metals, organochlorines and stable isotopes in narwhals (Monodon monoceros) from West Greenland".Science of the Total Environment.331 (1–3):83–105.Bibcode:2004ScTEn.331...83D.doi:10.1016/j.scitotenv.2004.03.041.ISSN0048-9697.PMID15325143.
_scavenging_a_narwhal_whale_(Monodon_monoceros)_carcass_-_journal.pone.0060797.g001-A.png)
_(14766096922).jpg)
.jpg)
