Mammal Species of the World
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- Original description: Linnaeus, C., 1758. Systema Naturae per regna tria naturae, secundum classis, ordines, genera, species cum characteribus, differentiis, synonymis, locis. Tenth Edition, Laurentii Salvii, Stockholm, 1:75, 824 pp.
Narwhal (Monodon monoceros) is an arctic cetacean, famous for its tusk, belong to Monodontidae (one of two whale species in the family along with Delphinapterus luecas). They live in arctic coastal waters and rivers. They are known as seasonal migrants that travel between bays and fjords in the summer and deep offshore area heavily packed in ice in the winter. In summer months, they move closer to coast which is an ice-free waters (usually in shallow one) then move offshore in winter to a deeper waters with densely packed ice on top of it though sometime surfacing in small leads in the ice (Laidre et al, 2002). They prefer deep or offshore waters almost in all area of occurrence and rarely seen south of 65oN latitude (Hay and Manfield, 1989). Supported by their ability to do deep dives and blubber up to 35% of their body weight insulation, living in a deep freezing water by the winter is not a problem.
- Laidre, K.L., Heide-Jørgensen,M.P., & Dietz, R. 2002. Diving behaviour of narwhal (Monodon monoceros) at two coastal localities in the Canadian High Arctic. Canadian Journal of Zoology, 80, 624-635.
- Hay, K. A. and Mansfield, A. W. 1989. Narwhal Monodon monoceros Linneaus, 1758. In: S. H. Ridgway and R. Harrison (eds), Handbook of marine mammals, pp. 145-176. Academic Press, London, UK.
The map shows where the species may occur based on oceanography. The species has not been recorded for all the states within the hypothetical range as shown on the map. States for which confirmed records of the species exist are included in the list of native range states.
Narwhals (Monodon monoceros) are regularly found eastwards from the Canadian Arctic to central Russia, but occur infrequently or rarely in eastern Siberia, Alaska, and the western Canadian Arctic. They mostly remain above the Arctic Circle year-round, but stragglers have been recorded around Newfoundland, Europe, and the eastern Mediterranean (Minasian, 1984).
Biogeographic Regions: arctic ocean (Native )
occurs (regularly, as a native taxon) in multiple nations
Regularity: Regularly occurring
Type of Residency: Year-round
Regularity: Regularly occurring
Type of Residency: Year-round
Global Range: Locally abundant in the high Arctic. Local concentrations occur in Davis Strait, Baffin Bay and adjacent waters, and the Greenland Sea. Smaller numbers occur in Hudson Strait, northern Hudson Bay, Foxe Basin, and Barents Sea. Presence in the Beaufort, Bering, and eastern Chukchi seas is exceptional. Also occurs in "Soviet" Arctic (Leatherwood and Reeves 1983). Most common in the eastern Canadian arctic and west Greenland area (IUCN 1991, which see for further details on distribution).
Head and body length, exclusive of the tusk, is 360-620 cm, pectoral fin length is 30-40 cm, and expanse of the tail flukes is 100-120 cm. According to Reeves and Tracey (1980) average head and body length is about 470 cm in males and 400 cm in females and average weight is 1,600 kg in males and 900 kg in females. About one-third of the weight is blubber. Coloration becomes paler with age. Adults have brownish or dark grayish upper parts and whitish underparts, with a mottled pattern of spots throughout. The head is relatively small, the snout blunt, and the flipper is short and rounded. There is no dorsal fin, but there is an irregular ridge about 5 cm high and 60-90 cm long on the posterior half of the back. The posterior margins of the tail flukes are strongly convex, rather than concave or straight as in most cetaceans.
There are only two teeth, both in the upper jaw. In females the teeth usually are not functional and remain embedded in the bone. In males the right tooth remains embedded, but the left tooth erupts, protrudes through the upper lip, and grows forward in a counterclockwise spiral pattern to form a long, straight tusk. The tusk is about one-third to one-half as long as the head and body and sometimes reaches a length of 300 cm and a weight of 10 kg. In rare cases the right tooth also forms a tusk, but both tusks are always twisted in the same direction. Occasionally one or even two tusks develop in a female. The distal end of the tusk has a polished appearance, and the remainder is usually covered by a reddish or greenish growth of algae. There is an outer layer of cement, an inner layer of dentine, and a pulp cavity that is rich in blood. Broken tusks are common, but the damaged end is filled by new dentine growth (Reeves & Tracey, 1980).
Range mass: 900 to 1600 kg.
Range length: 400 to 470 cm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: male larger; ornamentation
Length: 500 cm
Weight: 1600000 grams
Size in North America
Average: 4.7 m males; 4.1 m females
Average: 1,580 kg males; 960 kg females
Habitat and Ecology
Fish, squid, and shrimp make up the Narwhalâs diet (Hay and Mansfield 1989; Heide-Jorgensen 2002), especially Arctic fish species, such as Greenland halibut, Arctic Cod, and Polar Cod (the latter of which are often associated with undersides of ice) (Laidre and Heide-JÃ¸rgensen 2005a). Narwhals feed mostly in deep water and possibly at or near the bottom. Dives of up to nearly 1,500 m and 25 minutes are documented (Laidre et al. 2003), and there are some seasonal differences in the depth and intensity of diving (Laidre et al. 2002, Laidre et al. 2003). Predators include Killer Whales, Polar Bears, and possibly occasionally Greenland Sharks and Walruses (Hay and Mansfield 1989).
Monodon monoceros occupies one of the most northerly habitats of any cetacean species, between 70°N and 80°N, and seems to have more specific habitat requirements, and thus a more restricted range, than other cetaceans. Narwhals are rarely found far from loose pack ice and they prefer deep water. There are large concentrations in the Davis Strait, around Baffin Bay, and in the Greenland Sea. The advance and retreat of the ice initiates migration.
During summer, narwhals occupy deep bays and fjords; the best known and probably largest narwhal population in the world inhabits the deep inlets, sounds and channels of the eastern Canadian Arctic and north-west Greenland. When ice cover is low in larger, deeper water bodies, they move to smaller water bodies, which are steep-sided and deep. These traditional summering areas at the heads of fjords are probably important areas for calving. The narwhal’s preference for deep water in summer separates them from beluga whales which spend the summer mainly in shallow estuaries and bays (Klinowska, 1991).
Range depth: 400 to 800 m.
Habitat Regions: polar
Aquatic Biomes: pelagic ; coastal
Habitat Type: Marine
Comments: Bays, fiords, and inlets in warmer months; moves south into deeper water when ice begins to form. Not often far from loose pack ice. Near northern Baffin Island in summer, made both shallow dives and deep (to 257 m) dives to bottom (Martin et al., 1994, Can. J. Zool. 72:118-125). Probably dive to depths of more than 1000 meters (Reeves, in Wilson and Ruff 1999).
Non-Migrant: No. All populations of this species make significant seasonal migrations.
Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).
Locally Migrant: Yes. At least some populations of this species make annual migrations of over 200 km.
Migrates between northerly summer range and winter range to south. Inshore movement in summer dramatic and predictable, coincides with breakup of ice cover. Annual migrations appear responsive to ice formation and drift. (Leatherwood and Reeves 1983).
Narwhals have a varied diet, feeding upon squid, fish and crustaceans. With few functional teeth this animal is thought to use suction and the emission of a jet of water to dislodge prey such as bottom-living fish and molluscs. Their highly flexible necks aid in scanning a broad area and the capture of more mobile prey.
Foods eaten include: Polar cod, Greenland halibut, flounder, salmon, herring, crustaceans and cephalopods (octopuses and squids).
Animal Foods: fish; mollusks; aquatic crustaceans
Primary Diet: carnivore (Piscivore , Eats non-insect arthropods, Molluscivore )
Comments: Known prey includes squid, polar cod, demersal fishes, and crustaceans (Leatherwood and Reeves 1983).
Narwhals harbour several species of commensal animals such as whale lice and certain nematodes. They act to limit the populations of their prey species.
- Whale lice
Some have suggested that the tusk is used for anti-predatory functions, this is unsupported by evidence. Nonetheless, the tusk, which can grow to 3 m, would be a formidable weapon.
This list may not be complete but is based on published studies.
Known prey organisms
Based on studies in:
Canada, high Arctic (Ice cap)
This list may not be complete but is based on published studies.
- M. J. Dunbar, Arctic and subarctic marine ecology: immediate problems, Arctic 7:213-228, from p. 223 (1954).
- M. S. W. Bradstreet and W. E. Cross, Trophic relationships at High Arctic ice edges, Arctic 3(1)5:1-12, from p. 9 (1982).
- Myers, P., R. Espinosa, C. S. Parr, T. Jones, G. S. Hammond, and T. A. Dewey. 2006. The Animal Diversity Web (online). Accessed February 16, 2011 at http://animaldiversity.org. http://www.animaldiversity.org
10,000 to >1,000,000 individuals
Comments: About 18,800 occur in Canadian waters in summer; no population trend is evident (Strong 1988). Total population in the 1980s probably was somewhere between 25,000 and 50,000 (Evans 1992; see also IUCN 1991). Further information on populations is needed (IUCN 1991).
Large aggregations sometimes observed; these are subdivided into cohesive units of 20 or fewer individuals. Different sexes and ages may segregate or mix.
Life History and Behavior
Monodon monoceros may live up to 50+ years in the wild, yet attempts at captive breeding have been unsuccessful. Upon reaching the captive establishment, M. monoceros have only survived from 1 to 4 months. Considering the adult male can grow to 7m long, the species is usually too big to keep in captivity except at the largest of establishments (Klinowska, 1991).
Status: wild: 30 to 55 years.
Status: captivity: 1 to 4 months.
Status: wild: 40.0 years.
Lifespan, longevity, and ageing
The mating system of narwhals is unknown.
Monodon monoceros is a seasonal breeder. The gestation period is about 15.3 months, with mating occurring in March-May and calving in July-August of the following year. Lactation duration is unknown, but thought to be comparable to the white whale (Delphinapterus leucas) of 20 months. The interval between successive conceptions is normally three years. Monodon monoceros copulate vertically in the water, belly to belly. Infant narwhals are usually implanted in the left uterine horn. A single calf is often the result of gestation, yet some twins have been recorded. Birth takes place tail first (Klinowska, 1991). The newborn is born with 25 mm of blubber. Calves usually measure between 1.5 and 1.7 m and weigh 80 kg. Physical maturity is attained at a length of 4 m and a weight of 900 kg in females and 4.7 m and 1600 kg in males. This usually corresponds to 4 to 7 years of age (Reeves & Tracey, 1980).
Breeding season: March to May
Range number of offspring: 1 to 2.
Range gestation period: 12 to 15.3 months.
Average gestation period: 13 months.
Range weaning age: 12 to 24 months.
Range age at sexual or reproductive maturity (female): 4 to 7 years.
Range age at sexual or reproductive maturity (male): 4 to 7 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); viviparous
Average birth mass: 80000 g.
Average number of offspring: 1.
Young narwhals are capable of swimming soon after birth. They are nursed and protected by their mothers for extended periods after birth.
Parental Investment: precocial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female); pre-independence (Provisioning: Female, Protecting: Female); extended period of juvenile learning
Breeds in March-May. Single calf is born in summer after gestation of about 14-15 months. Lactation exceeds 1 year, may extend up to 2 years. Calving interval most often is 3 years. Males probably sexually mature in 8-9 years, females in about 4-7 years.
Evolution and Systematics
The tusks of male narwhals may detect chemicals related to ice formation, salinity, or prey using a vast network of fluid-filled tubules connected to the tusk's central nerve.
"It could be a jousting tool or an ice-breaker. It has even been attributed to the legendary unicorn. But the true purpose of the narwhal's spectacular spiral tusk has remained a mystery.
"Now Martin Nweeia at Harvard School of Dental Medicine and his colleagues have come up with another explanation. They believe the tusk, which can measure up to 2.75 metres, could act as a sensor, helping the narwhal to survive in its Arctic home by detecting chemicals associated with prey, ice formation and salt concentrations.
"Two tusks taken from recently caught narwhals were examined under an electron microscope. This revealed a vast network of around 10 million fluid-filled tubules connecting the tusk's central nerve to the surrounding water. Such tubules exist in human teeth, but are only exposed at areas of gum recession, where they cause extreme sensitivity. 'The last place you would expect to have something so sensitive is a cold Arctic environment,' says Nweeia. A further surprise came when a laser was used to map the chemical composition of the tusk, a technique called reflectance microspectroscopy. It revealed that the narwhal's tusk is 'inside out'. Most teeth are hard on the outside and soft inside, but the narwhal's tusk has a soft protein-rich exterior, while the inside is more mineralised. 'Everything about these findings is counter-intuitive,' says Nweeia." (Geddes 2005:6)
Learn more about this functional adaptation.
- Linda Geddes. 2005. What's the point of the narwhal's tusk?. New Scientist. 188(2531/2532):
Molecular Biology and Genetics
Barcode data: Monodon monoceros
There are 11 barcode sequences available from BOLD and GenBank. Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species. See the BOLD taxonomy browser for more complete information about this specimen and other sequences.
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Download FASTA File
Statistics of barcoding coverage: Monodon monoceros
Public Records: 2
Specimens with Barcodes: 15
Species With Barcodes: 1
IUCN Red List Assessment
Red List Category
Red List Criteria
Across the global range of the species, subpopulations are subject to differing levels of threat and warrant individual assessment. Therefore, a caveat for the global listing as Near Threatened is that it assumes national and international management authorities will continue to monitor and manage harvest levels. Hunting with modern equipment in specific parts of Greenland and Canada represents the most long-standing and consistent threat to narwhals throughout their range. Several small and/or depleted subpopulations (e.g. West Greenland and Hudson Bay) warrant individual assessment as an immediate priority.
- 1996Data Deficient(Baillie and Groombridge 1996)
- 1996Data Deficient
- 1994Insufficiently Known(Groombridge 1994)
- 1990Insufficiently Known(IUCN 1990)
- 1988Insufficiently Known(IUCN Conservation Monitoring Centre 1988)
National NatureServe Conservation Status
Rounded National Status Rank: N3 - Vulnerable
Rounded National Status Rank: NU - Unrankable
Monodon monoceros is listed as CITES Appendix II and IUCN Data Deficient. As in most ivory bearing mammals around the world, destruction of individuals for their ivory is a constant threat.
US Federal List: no special status
CITES: appendix ii
IUCN Red List of Threatened Species: near threatened
- Klinowska, M. 1991. Dolphins, Porpoises and Whales. The IUCN Red Data Book. Gland, Switzerland: IUCN.
NatureServe Conservation Status
Rounded Global Status Rank: G4 - Apparently Secure
The estimated generation length for the narwhal according to Taylor et al. (2007) is 24 years, which means that the 3-generation window is 1936-2008.
In West Greenland, catches have declined since 1993 with no significant sex bias. Heide-Jorgensen (2002) estimated the annual catch rate at 550 between 1993 and 1995. In 2004, the estimated catch in West Greenland was 294 (NAMMCO/JCNB 2005), including whales that were struck and lost. In contrast to West Greenland, there has been an 8% increase in catches in East Greenland since 1993 (NAMMCO/JCNB 2005).
The narwhal is actively hunted only in Canada and Greenland. In the eastern Canadian Arctic, the average reported landed catch per year from selected communities was 373 between 1996 and 2004 (NAMMCO/JCNB 2005). In Canada the majority of the communities take a greater proportion of males than females throughout the seasons. Annual catch statistics in Canada substantially underestimate the total numbers of Narwhals killed due primarily to the incomplete reporting of whales that are struck and killed but lost (IWC 2000; NAMMCO/JCNB 2005; Nicklen 2007).
Narwhals supplied various staples in the traditional subsistence economy. Today the main products are mattak and ivory (Reeves 1993, Reeves and Heide-JÃ¸rgensen 1994, Heide-JÃ¸rgensen 1994, Nicklen 2007). Narwhal tusks from Canada and Greenland are sold in specialty souvenir markets domestically and also have been exported. However, in Greenland, the export of tusks is currently banned. In Canada, the quota system that had been in place since the 1970s was replaced by a community-based management system implemented in the late 1990s and early 2000s (COSEWIC 2004). The hunt is managed by local hunter and trapper organizations with harvest limits established in some communities. Compliance has been questionable (COSEWIC 2004). Under this system, removals from some summering aggregations are probably sustainable, however, there is concern that removals from other summering aggregations may not be (NAMMCO/JCNB 2005). In Greenland, a quota system was introduced in 2004 by the Greenland Ministry of Fisheries and Wildlife. The quota was set at 300 Narwhals (of which 294 were taken), divided among municipalities of West Greenland. Compliance reportedly has been good (NAMMCO/JCNB 2005) although there is concern that catch limits may be set too high (IWC 2007, p. 52).
The effects of climate change on Narwhals are uncertain. Narwhals are well adapted to a life in the pack ice as indicated by the fact that there is very little open water in their winter habitat (Laidre and Heide-JÃ¸rgensen 2005b). They spend much of their time in heavy ice and are vulnerable to ice entrapments where hundreds can become trapped in a small opening in the sea ice (savssat) and die. This occurs when sudden changes in weather conditions (such as shifts in wind or quick drops in temperature) freeze shut leads and cracks they were using. When entrapped whales are discovered by hunters, they normally are killed. A recent assessment of the sensitivity of all Arctic marine mammals to climate change ranked the narwhal as one of the three most sensitive species, primarily due to its narrow geographic distribution, specialized feeding and habitat choice, and high site fidelity (Laidre et al. in press).
Comments: Subsistence hunting evidently does not pose a significant threat at current levels, but further data are needed; potentially threatened by pollution and activities associated with development of mineral and hydrocarbon resources (IUCN 1991).
The European Union (EU), with stronger CITES rules than other countries, has established an import ban on tusks (active since December 2004). Although Denmark belongs to the EU, it is unclear whether the ban on trade in narwhal ivory between Greenland and Denmark is being enforced.
Needs: See IUCN (1991) for a discussion of conservation measures.
Relevance to Humans and Ecosystems
Economic Importance for Humans: Negative
There are no known adverse affects to humans.
Economic Importance for Humans: Positive
Historically narwhals were a staple food source of many Arctic peoples. Arctic people used the narwhals body for a number of other uses. The blubber can be rendered for oil, the sinew used as thread, and the tusks traded and carved.
Positive Impacts: food ; ecotourism ; research and education
Comments: Long subjected to subsistence harvest for meat, blubber, skin, sinews, and tusk. Still hunted for subsistence (probably around 1000 killed annually in Canada and Greenland); no commercial harvest, though tusk enters international trade. See IUCN (1991) for a summary of historical exploitation.
IUCN Red List Category
- IUCN (2008) Cetacean update of the 2008 IUCN Red List of Threatened Species.
The narwhal, or narwhale (Monodon monoceros), is a medium-sized toothed whale and the animal with the largest canines. It lives year-round in the Arctic. One of two living species of whale in the Monodontidae family, along with the beluga whale, narwhal males are distinguished by a long, straight, helical tusk, actually an elongated upper left canine. Found primarily in Canadian Arctic and Greenlandic waters, rarely south of 65°N latitude, the narwhal is a uniquely specialized Arctic predator. In the winter, it feeds on benthic prey, mostly flatfish, at depths of up to 1500 m under dense pack ice. Narwhals have been harvested for over a thousand years by Inuit people in northern Canada and Greenland for meat and ivory, and a regulated subsistence hunt continues to this day. While populations appear stable, the narwhal is particularly vulnerable to climate change due to a narrow geographical range and specialized diet.
Taxonomy and etymology
The narwhal was one of the many species originally described by Linnaeus in his Systema Naturae. Its name is derived from the Old Norse word nár, meaning "corpse", in reference to the animal's greyish, mottled pigmentation, like that of a drowned sailor and its summer-time habit of lying inactive at or near the surface of the sea (called "logging"). The scientific name, Monodon monoceros, is derived from Greek: "one-tooth one-horn" or "one-toothed unicorn".
The narwhal is most closely related to the beluga whale. Together, these two species comprise the only extant members of the family Monodontidae, sometimes referred to as the "white whales". The Monodontidae are distinguished by medium size (at around 4 m (13 ft) in length), forehead melons, short snouts, and the absence of a true dorsal fin. The white whales, dolphins (Delphinidae) and porpoises (Phocoenidae) together comprise the superfamily Delphinoidea, which are of likely monophyletic origin. Genetic evidence suggests the porpoises are more closely related to the white whales, and that these two families constitute a separate clade which diverged from the Delphinoidea within the past 11 million years.
These are medium-sized whales, being around the same size as a beluga whale. Total length in both sexes, excluding the "tusk" of the male, can range from 3.95 to 5.5 m (13 to 18 ft). Males, at an average length of 4.1 m (13 ft 5 in), are slightly larger than females, at an average of 3.5 m (11 ft 6 in). Typical adult body weight can range from 800 to 1,600 kg (1,800 to 3,500 lb). Males attain sexual maturity at 11 to 13 years of age, when they are approximately 3.9 m (12 ft 10 in) long, and females attain maturity at 5 to 8 years old, when they are 3.4 m (11 ft 2 in) long. The pigmentation of the narwhal is a mottled pattern, with blackish-brown markings over a white background. They are darkest when born and become whiter in color with age, with white patches developing on the navel and genital slit at sexual maturity. Old males may be almost pure white. Narwhals do not have a dorsal fin, possibly an evolutionary adaptation to swimming easily under ice. In addition, the neck vertebrae of the narwhal are not fused together, but are jointed, like those of land mammals. Both these characteristics are shared by the beluga whale (Delphinapterus leucas), a fellow inhabitant of icy Arctic seas.
The most conspicuous characteristic of the male narwhal is its single extremely long tusk, a canine tooth that projects from the left side of the upper jaw, through the lip and forms a left-handed helix. The tusk grows throughout life reaching lengths from 1.5 to 3.1 m (4 ft 11 in to 10 ft 2 in). Despite its formidable appearance, the tusk is hollow and weighs only around 10 kg (22 lb). About one in 500 males has two tusks, which occurs when the right canine, normally small and less straight, also grows out through the lip. Females may grow tusks sometimes, although the evidence on the frequency of this is somewhat conflicting. It has been stated that only about 15 percent of females have a tusk and that "When the occasional female narwhal grows a tusk, the female narwhal tusk tends to be much smaller than the male narwhal tusk, with a less pronounced spiral.". Elsewhere, it has been stated that "In most females the teeth never erupt through the gum" and "Female narwhals have a shorter, and straighter tusk" but with no comment on the frequency of occurrence. Females may produce a second tusk, but there is only a single recorded case of a female with dual tusks.
Biology considers the tusk a secondary sexual characteristic, similar to the mane of a lion or the tail feathers of a peacock. Charles Darwin discussed and defended this hypothesis at length in The Descent of Man, and Selection in Relation to Sex (1871). It may help determine social rank, maintain dominance hierarchies, or help young males develop skills necessary for performance in adult sexual roles. Narwhals have rarely been observed using their tusk for fighting, other aggressive behavior or for breaking sea ice in their Arctic habitat. Some narwhals have a second, small tooth in their mouths, but are essentially toothless. The tusk is a highly innervated sensory organ, as scientists finally established in the early years of the 21st century after many centuries of myth and fiction ascribing it other roles, ranging from magical to weaponry. There is at least one known instance where a tusk was used against another species. The broken tip of a narwhal tusk was found embedded in the melon of a beluga, suggesting there was an aggressive encounter.
The narwhal is found predominantly in the Atlantic and Russian areas of the Arctic Ocean. Individuals are commonly recorded in the northern part of Hudson Bay, Hudson Strait, Baffin Bay; off the east coast of Greenland; and in a strip running east from the northern end of Greenland round to eastern Russia (170° East). Land in this strip includes Svalbard, Franz Joseph Land, and Severnaya Zemlya. The northernmost sightings of narwhal have occurred north of Franz Joseph Land, at about 85° North latitude. Most of the world's narwhals are concentrated in the fjords and inlets of Northern Canada and western Greenland.
Behavior and diet
Narwhals have a relatively restricted and specialized diet. Their prey is predominantly composed of Greenland halibut, polar and Arctic cod, cuttlefish, shrimp and armhook squid. Additional items found in stomachs have included wolffish, capelin, skate eggs and sometimes rocks, accidentally ingested when whales feed near the bottom. Due to the lack of well-developed dentition in the mouth, narwhals are believed to feed by swimming towards prey until it is within close range and then sucking it with considerable force into the mouth. It is thought that the beaked whales, who have similarly reduced dentition, also suck up their prey.
Narwhals exhibit seasonal migrations, with a high fidelity of return to preferred, ice-free summering grounds, usually in shallow waters. In summer months, they move closer to coasts, usually in pods of 10–100. In the winter, they move to offshore, deeper waters under thick pack ice, surfacing in narrow fissures in the sea ice, or leads. Narwhals from Canada and West Greenland winter regularly in the pack ice of Davis Strait and Baffin Bay along the continental slope with less than 5% open water and high densities of Greenland halibut. Feeding in the winter accounts for a much larger portion of narwhal energy intake than in the summer and, as marine predators, they are unique in their successful exploitation of deep-water arctic ecosystems.
Most notable of their adaptations is the ability to perform deep dives. When on their wintering grounds, the narwhals make some of the deepest dives ever recorded for a marine mammal, diving to at least 800 meters (2,600 feet) over 15 times per day, with many dives reaching 1,500 meters (4,900 feet). Dives to these depths last around 25 minutes, including the time spent at the bottom and the transit down and back from the surface. In the shallower summering grounds, narwhals dive to depths between 30 and 300 meters (98 and 984 ft).
Narwhals normally congregate in groups of about five to ten individuals, sometimes up to 20 outside the summer. Groups may be "nurseries" with only females and young or can contain only post-dispersal juveniles or adult males ("bulls"), though mixed groups can occur at any time of the year. In the summer, several groups come together, forming larger aggregations. Such aggregations can contain from 500 to over 1000 individuals. At times, bull narwhals rub their tusks together in an activity called "tusking". This behavior is thought to maintain social dominance hierarchies or maintenance of the tusk as a sensitive sensory organ.
Narwhals have evolved complex and sophisticated systems using sound to investigate their environment and to find food. The narwhal can create "clicks", "whistles" and "knocks", probably by controlling air between chambers near the blowhole, as is known to be done in other odontocete species. These sounds may then be reflected off the sloping front of the skull. The sounds may then be further focused by the melon, the round space on the head filled with a mix of blubber oils, and can be altered in shape under muscular control. "Click trains" are used by toothed whales for echo-location of prey, and for detecting obstacles at short ranges. It has been suggested that individual "bangs" could be strong enough to disorient or incapacitate prey, making the prey easier to catch, but that idea has not been verified. Whistles are rarely heard. Trumpeting and squeaking door sounds may also be used for communication among narwhals.
Breeding and early life
Females start bearing calves at six to eight years of age. Adult narwhals mate in April or May when they are in the offshore pack ice. Gestation lasts for 14 months and calves are born between June and August of the following year. Like most marine mammals, narwhals have only one calf at a time. Newborn calves average 1.6 metres in length and are dark grey. While the newborn calves have only a very thin layer of blubber, the mother’s milk is rich in fat and a thicker blubber layer soon develops in the calves. Calves are nursed about 20 months. The lengthy lactation period provides calves with time to learn the skills they need to survive. Mother and calf are usually close, and when the whales are traveling, the calf remains close to the mother’s back, where it may get assistance in swimming.
Mortality and conservation
Normally, narwhals can live quite a long life, with lifespans of up to at least 50 years recorded. Mortality often occurs when the narwhals suffocate after they fail to leave before the surface of the Arctic waters freeze over in the late autumn. Starvation can also threaten their lives, especially in young whales. Although almost all modern predation of narwhals is by humans, a few natural predators also attack them on occasion. The primary natural predators are polar bears, who attempt to swipe narwhals at breathing holes and mainly target young whales, a pod of killer whales (orcas) can overwhelm a single narwhal. Greenland sharks and walruses may take a few small young or weak and wounded adults, though this is likely quite rare. Inuit people, who call a tusked narwhal "qilalugaq tugaalik", are allowed to hunt this whale species legally for subsistence. Narwhal has been extensively hunted the same way as other sea mammals, such as seals and whales, for its large quantities of fat which constituted one of the most important resources of the native people living in arctic regions. Almost all parts of the narwhal, meat, skin, blubber and organs are consumed. Mattak, the name for raw skin and blubber, is considered a delicacy, and the bones are used for tools and art. The skin is an important source of vitamin C which is otherwise difficult to obtain. In some places in Greenland, such as Qaanaaq, traditional hunting methods are used, and whales are harpooned from handmade kayaks. In other parts of Greenland and Northern Canada, high-speed boats and hunting rifles are used.
Narwhal have been found to be one of the most vulnerable arctic marine mammals to climate change. The study quantified the vulnerabilities of 11 year-round Arctic sea mammals. Narwhals that have been brought into captivity tend to die of natural causes. The world population of narwhals is currently estimated to be around 75,000. Approximately 25,000–50,000 breeding narwhal are believed to exist in the wild worldwide. The status of Narwhals is currently near threatened even though several sub-populations have evidence of decline. It is estimated that by 2017 they will reach threatened status. In an effort to support conservation actions for the whales, the European Union established an import ban on tusks. While there are many countries that have not only established these bans, they already have quotas on catches in place, which will be important also in newly opening areas caused by decreasing sea ice cover.
Relation with humans
In Inuit legend, the narwhal's tusk was created when a woman with a harpoon rope tied around her waist was dragged into the ocean after the harpoon had struck a large narwhal. She was transformed into a narwhal herself, and her hair, which she was wearing in a twisted knot, became the characteristic spiral narwhal tusk.
Some medieval Europeans believed narwhal tusks to be the horns from the legendary unicorn. As these horns were considered to have magic powers, such as the ability to cure poison and melancholia, Vikings and other northern traders were able to sell them for many times their weight in gold. The tusks were used to make cups that were thought to negate any poison that may have been slipped into the drink. During the 16th century, Queen Elizabeth received a carved and bejeweled narwhal tusk for £10,000—the cost of a castle (approximately £1.5–2.5 million in 2007, using the retail price index). The tusks were staples of the cabinet of curiosities. The truth of the tusk's origin developed gradually during the Age of Exploration, as explorers and naturalists began to visit Arctic regions themselves. In 1555, Olaus Magnus published a drawing of a fish-like creature with a horn on its forehead, correctly identifying it as a "Narwal". The narwhal was one of two possible explanations of the giant sea phenomenon written by Jules Verne in his book Twenty Thousand Leagues Under the Sea. The other possible explanation was a man-made vessel, but that was not likely in the opinion of the narrator.
Herman Melville wrote a section on the narwhal in Moby Dick, in which he claims a narwhal tusk hung for "a long period" in Windsor Castle after Sir Martin Frobisher had given it to Queen Elizabeth.
In 2013, Canadian artist Harley Valentine created the sculpture North Pole, a gold-polished, lost wax bronze cast of a seven foot, 100-year old narwhal tusk thought to have come from Grise Fiord in the Canadian Arctic.
Climate change vulnerability
The extreme morphological and physiological traits which they adapted in order to allow them to reside in the harsh Arctic conditions may also limit their behavioral flexibility towards changing sea ice and temperature. Their tissue is composed largely of slow twitch oxidative muscle and contains one of the highest levels of Myoglobin in marine mammals; this provides significant endurance and helps them dive for about 15–24 minutes assuming they maintain their metabolic rate. They also possess specialized skeletal muscles that are geared towards allowing slow endurance swimming and prolonged diving behavior. These muscles share similarities with the muscles used for running in human athletes. When it comes to escaping predators such as orcas, they typically choose prolonged submergence to hide under the ice rather than relying on speed. Since they are highly adapted through body morphology and skeletal muscle characteristics to the Arctic conditions, free-ranging narwhals may be reaching their physiological capacity in current environmental conditions. They are large in size which provides advantages in thermoregulation, however this can prove problematic when finding cracks in the ice large enough to allow them to breathe.
Narwhals are long lived species which is beneficial for producing a few healthy offspring better fit for survival, but it also decreases their ability to respond to quickly changing environmental conditions since they reproduce at a much slower rate. Narwhal population size is considered small compared to original conditions resulting from centuries of heavy commercial and subsistence harvesting that the population has not been able to recover.
Impact of sea ice change
One of the aspects that make narwhals vulnerable to climate change is the altering sea ice coverage in their environment, especially in their Northern wintering grounds such as the Baffin Bay and Davis Straitt regions. Satellite data collected from these areas shows the amount of sea ice has been markedly reduced. In Baffin Bay there has been about a 9% sea ice decline per decade in the East. This has been accompanied with earlier breakup of spring sea ice in Baffin Bay. West Greenland ocean temperatures have been warming prominently since 2000 as a result of increased inflow from warmer waters from the Irminger Current into South and West Greenland. The IPCC report predicts that the doubling of CO2 in the atmosphere will lead to the decline of 60% of the sea ice cover in the summer, which has the potential to alter production levels and alter the ecosystem. Narwhal’s ranges for foraging are believed to be patterns developed early in their life which are intended to increase their ability to gain necessary food resources during winter stages. This strategy focuses on strong site fidelity rather individual level response to local prey distribution and this result in focal foraging areas during the winter so despite changing conditions Narwhals will continue returning to the same areas during migration.
Another potential problem faced by narwhals is the risk of sea ice entrapment in their wintering grounds. Open water is formed in ice-covered water by fracturing events that are induced by strong winds, however when these conditions are absent ice can quickly form. This correlates with the observations that the last major entrapment events occurred when there was little to no wind observed in the area. Since narwhals are mammals they need air to breathe, so when open water is no longer accessible and the ice is too thick for them to break through, they can end up drowning. Maximum aerobic swimming distance between breathing holes in ice is less than 1,450 m which limits the use of foraging grounds and these holes must be at least 0.5 m wide to allow an adult whale to breathe. The events can trap groups as large as 600 individuals. Most entrapment events occur in narwhal wintering areas such as Disko Bay and the largest entrapment event occurred in 1915 in West Greenland where over 1,000 narwhals were trapped under the ice. Despite the decreases in Sea ice cover, there have been several large cases of sea ice entrapment in 2008–2010 that occurred in the winter but close to known summering grounds, two of which were locations where there had been no previous cases documented. This suggests later departure dates from summering grounds, which were recorded to be moving toward late autumn or even winter. Sites surrounding Greenland experience advection of sea ice from surrounding regions by wind and currents, which increased the variability of when sea ice concentration reached certain thresholds and at what date. Also, due to strong site fidelity, changes in weather and ice conditions are not always associated with narwhal movement toward open water and therefore more data is needed to determine how vulnerable narwhals are to future sea ice changes.
While temperature may be increasing, there are also microhabitat cases of sea ice increases in the arctic. These micro-habitats were found in Baffin Bay, Davis Strait, coastal West Greenland and Lancaster Sound. While the cause of sea ice cooling in areas such as Baffin Bay is uncertain, it is most likely associated with changes in the thermohaline circulation, the North Atlantic Oscillation and the formation of sea ice bridge in Smith Sound. This also plays a factor in increased sea ice entrapment vulnerability.
An indirect danger for narwhals associated with changes in sea ice is the increased exposure in open water. In 2002 there was an increase in narwhal catches by hunters in Siorapaluk that did not appear to be associated with increased effort. Climate change therefore may be making them more vulnerable to harvesting. Scientists urge assessment of population numbers and the assignment of sustainable quotas for stocks of as well as the collaboration of management agreements to ensure local acceptance. Seismic surveys associated with oil exploration have also been noted to disrupt normal migration patterns which may also be associated with increased sea ice entrapment.
- Mead, J. G.; Brownell, R. L., Jr. (2005). "Order Cetacea". In Wilson, D. E.; Reeder, D. M. Mammal Species of the World (3rd ed.). Johns Hopkins University Press. pp. 723–743. ISBN 978-0-8018-8221-0. OCLC 62265494.
- Jefferson, T.A., Karczmarski, L., Laidre, K., O’Corry-Crowe, G., Reeves, R.R., Rojas-Bracho, L., Secchi, E.R., Slooten, E., Smith, B.D., Wang, J.Y. & Zhou, K. (2008). Monodon monoceros. In: IUCN 2008. IUCN Red List of Threatened Species. Retrieved 18 December 2008.
- Laidre, K (2004). "Deep-ocean predation by a high Arctic cetacean". ICES Journal of Marine Science 61 (1): 430–440. doi:10.1016/j.icesjms.2004.02.002.
- Laidre, K. L.; Stirling, I.; Lowry, L.; Wiig, Ø.; Heide-Jørgensen, M. P. and Ferguson, S. (2008). "Quantifying the sensitivity of arctic marine mammals to climate-induced habitat change". Ecological Applications 18 (2): S97–S125. doi:10.1890/06-0546.1. PMID 18494365.
- (Latin) Linnaeus, C (1758). Systema naturae per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata. Holmiae. (Laurentii Salvii). p. 824.
- Heide-Jørgensen, M. P. and Laidre, K. L. (2006). Greenland’s Winter Whales: The beluga, the narwhal and the bowhead whale. Ilinniusiorfik Undervisningsmiddelforlag, Nuuk, Greenland. ISBN 978-87-7975-299-3.
- "The Narwhal: Unicorn of the Seas". Fisheries and Oceans Canada. 2007. Retrieved 10 July 2013.
- Brodie, Paul (1984). Macdonald, D., ed. The Encyclopedia of Mammals. New York: Facts on File. pp. 200–203. ISBN 0-87196-871-1.
- Waddell, V.G.; Milinkovitch, M.C.; Bérubé, M. and Stanhope, M.J. (2000). "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)". Molecular Phylogenetics and Evolution 15 (2): 314–318. doi:10.1006/mpev.1999.0751. PMID 10837160.
- Macdonald, D.W.; Barrett, P. (1993). Mammals of Europe. New Jersey: Princeton University Press. ISBN 0-691-09160-9.
- "Monodon monoceros". Fisheries and Aquaculture Department: Species Fact Sheets. Food and Agriculture Organization of the United Nations. Retrieved 20 November 2007.
- Nweeia, Martin T.; Eichmiller, Frederick C.; Hauschka, Peter V.; Tyler, Ethan; Mead, James G.; Potter, Charles W.; Angnatsiak, David P.; Richard, Pierre R. et al. (2012). "Vestigial tooth anatomy and tusk nomenclature for Monodon monoceros". The Anatomical Record 295 (6): 1006–16. doi:10.1002/ar.22449. PMID 22467529.
- Lambert, K. "How Narwhals work". Retrieved 10 July 2013.
- "Narwhal Biology". NarwhalTusks.com. Retrieved 10 July 2013.
- "Narwhal". American Cetacean Society. Retrieved 10 July 2013.
- "Narwhal Whale Tusk". Narwhal Whales. Retrieved 10 July 2013.
- Carwardine, Mark (1995). DK Handbooks: Whales Dolphins and Porpoises. Dorling Kindersley. ISBN 1-56458-620-0.
- Silverman, H. B. and Dunbar, M. J. (1980). "Aggressive tusk use by the narwhal (Monodon monoceros L.)". Nature 284 (5751): 56–57. doi:10.1038/284057a0.
- Broad, William (13 December 2005). "It's Sensitive. Really.". The New York Times. mirror
- "The Biology and Ecology of Narwhals". National Oceanic and Atmospheric Administration. Retrieved 15 January 2009.
- Laidre, K.L. and Heide-Jørgensen, M. P. (2005). "Winter feeding intensity of narwhals". Marine Mammal Science 21 (1): 45–57. doi:10.1111/j.1748-7692.2005.tb01207.x.
- "Animal Bytes – Narwhal". Seaworld.org. Retrieved 21 April 2013.
- Laidre, K. L.; Heide-Jørgensen, M. P.; Dietz, R.; Hobbs, R. C. and Jørgensen, O. A. (2003). "Deep-diving by narwhals, Monodon monoceros: differences in foraging behavior between wintering areas?". Marine Ecology Progress Series 261: 269–281. doi:10.3354/meps261269.
- Borenstein, Seth (25 April 2008). "Narwhals more at risk to Arctic warming than polar bears". Associated Press. Retrieved 27 April 2008.
- Bastian, Dawn E; Judy K. Mitchell (2004). Handbook of Native American Mythology. ABC-CLIO. pp. 54–55. ISBN 1-85109-533-0.
- Daston, Lorraine and Park, Katharine (2001). Wonders and the Order of Nature, 1150–1750. New York: Zone Books, ISBN 0942299914.
- Purchasing Power of British Pounds from 1264 to 2007. measuringworth.com
- Shepard, Odell (1956). The Lore of the Unicorn. Harper and Row Publishers.
- Melville, Herman (1851). Moby-Dick; or, The Whale. Harper and Brothers.
- Brown, Cameron. (2013-02-15) Artist Harley Valentine Casts Natural Wonder | culture. Torontoist. Retrieved on 2013-06-17.
- Williams, Terrie M.; Noren, Shawn R.; Glenn, Mike (2011). "Extreme physiological adaptations as predictors of climate-change sensitivity in the narwhal, Mondon monceros". Marine Mammal Science 27 (2): 334. doi:10.1111/j.1748-7692.2010.00408.x.
- Laidre, KL; Heide-Jørgensen, MP (2011). "Life in the lead: extreme densities of narwhals Monodon monoceros in the offshore pack ice". Marine Ecology Progress Series 423: 269. doi:10.3354/meps08941.
- Perovich, DK; Richter-Menge, JA (2009). "Loss of sea ice in the Arctic". Annual review of marine science 1: 417–41. PMID 21141043.
- Stirling I, Parkinson CL (2006). "Possible effects of climate warming on selected populations of polar bears (Ursus maritimus) in the Canadian Arctic". Arctic 59: 261–275.
- Myers, Paul G.; Kulan, Nilgun; Ribergaard, Mads H. (2007). "Irminger Water variability in the West Greenland Current". Geophysical Research Letters 34 (17). doi:10.1029/2007GL030419.
- /publications_ipcc_fourth_assessment_report_wg2_report_impacts_adaptation_and_vulnerability.htm Climate Change 2007 – Impacts, Adaptation and Vulnerability Contribution of Working Group II to the Fourth Assessment Report of the IPCC ISBN 978052188010-7.
- Laidre K., Heide-Jorgensen, M.P.; Stern, H. and Richard, P. (2011). "Unusual narwhal sea ice entrapments and delayed autumn freeze-up trends". Polar Biology 35: 149. doi:10.1007/s00300-011-1036-8.
- Porsild, M. (1918). "On 'Savssat': A crowding of arctic animals at holes in the sea ice". Geogr Rev 6 (3): 215–228. doi:10.2307/207815. JSTOR 207815.
- Heide-Jorgensen M.P, and Laidre, K.L. (2004). "Declining extent of open-water refugia for top predators in Baffin Bay and adjacent waters". Ambio 33 (8): 487–94. PMID 15666678.
- Stern, H.L. and Heide-Jørgensen, M.P. (2003). "Trends and variability of sea ice in Bafﬁn Bay and Davis Strait". Polar Research 22: 11. doi:10.1111/j.1751-8369.2003.tb00090.x.
- Parkinson, C.L. (2000). "Recent trend reversals in Arctic sea ice extents: possible connections to the North Atlantic Oscillation". Polar Geography 31: 3. doi:10.1080/10889370802175945.
- Nielsen M.R. (2009). "Is climate change causing the increasing narwhal (Monodon monoceros) catches in Smith Sound, Greenland?". Polar Research 28 (2): 238. doi:10.1111/j.1751-8369.2009.00106.x.
- Heide-Jørgensen M.P., Hansen, R.G.; Westdal, K.; Reeves, R.R. and Mosbech, A. (2013). "Narwhals and seismic exploration: Is seismic noise increasing the risk of ice entrapments?". Biological Conservation 158: 50. doi:10.1016/j.biocon.2012.08.005.
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- M. P. Heide-Jorgensen. "Narwhal", in Encyclopedia of Marine Mammals, Perrin, Wursig and Thewissen eds. ISBN 0-12-551340-2
- Heide-Jørgensen, M. P. and K. L. Laidre (2006). Greenland’s Winter Whales: The beluga, the narwhal and the bowhead whale. Ilinniusiorfik Undervisningsmiddelforlag, Nuuk, Greenland. ISBN 978-87-7975-299-3.
- Groc, Isabelle. "Hunt for the sea unicorn", New Scientist feature article, Issue 2956, 15 February 2014