Biology and Cultural Importance of the Narwhal
Volume 12 of the Annual Review of Animal Biosciences by Martin T. Nweeia, DMD, DDS
Abstract
Though narwhal have survived multiple ice ages, including 2.5 Ma and the last
interglacial period with warming temperatures, Arctic climate change during the Anthropocene
introduces new challenges. Despite evolutionary connection to Arctic Pleistocene fossils,
narwhal archeocete ancestors from the Pliocene, Bohaskia montondontoides, Miocene,
Denbola and Odobenocetopsidae, inhabited warm waters. Arctic adaptation for narwhal holds
valuable insights of unique traits including thin skin, extreme diving capacity, and a unique
straight, spiraled, and sensory tooth organ system. Inaccessible weather, ice conditions and
darkness limit scientific studies, though Inuit knowledge adds valuable observations of narwhal
ecology, biology and behavior. Existing and future studies in myriad fields of physical,
chemical, biological, and genetic science, combined and integrated with remote sensing and
imaging technologies, will help uncover ongoing questions of narwhal evolution, biology and
adaptation. When integrated with Inuit Qaujimajimajatuqangit, “the Inuit way of knowing,” these
studies will help describe interesting biologic expressions of narwhal.
Cultural Importance of the Narwhal
Multiple epistemologies are useful and complementary in the investigation of narwhal
and, more broadly, in the Arctic environment. Perceptions and descriptions of narwhal and
Arctic biology benefit from the integration of Inuit-derived epistemology. Among these
approaches to knowledge are Qaujimajatuqangit, “the Inuit way of knowing” (IQ), and Isuma,
“wisdom, to think or thinking.” IQ is an oral tradition passed on through generations by keen
observations of Inuit and are contextual, integrating multiple environmental variables, as Inuit
are inextricably linked to their land with knowledge created from decisions that are time-
dependent for survival. Mythology and dream interpretation may also be included with IQ.
Since respect for the environment and gratitude for its offerings are at the core of IQ,
knowledge is implemented with reverence for all animals, including the narwhal. Technologies
used in narwhal hunting, such as the “qamutik” Inuit sled and “qajait, or qayaq,” kayak, are
designed to have minimal impact to transportation in a harsh environment. In the case of kayak
construction, the technology is specifically built for each person with considerations of size,
weight, and arm reach, and includes design elements tailored to the waters being used. The
person and their relationship with the environment defines the technology (1). Technology
does not attempt to control environment, but is respectful of it (2).
Forced relocation, colonization and language oppression, defined as “enforcement of
language loss by physical, mental, social and spiritual coercion,” interrupted the passage of
knowledge for one generation. Revitalization of Qaujimajatuqangit continues, with post-colonial
changes that are associated with a resurgence of Inuit culture and language. IQ is valuable,
and should be harnessed more for scientific advancement. Successful scientific collaboration
depends on an appreciation of IQ, respect for Inuit values, and recognition of past colonial
efforts to abolish Inuit culture, language and wisdom. Though previous researchers have cited
specific contributions on narwhal from IQ, more recent studies of narwhal anatomy, physiology,
migration and behavior have broadened the applications of how this knowledge can be utilized
and valued even more in the future. Formal recognition is necessary through collaborative
efforts or Isumaqatigingniq to continue Inuit-scientist collaborations, in all forms of outreach
including scientific conferences and publications.Scientific Approaches to IQ Integration
Scientists have taken a variety of approaches to IQ inclusion ranging from none, to a
communication citation, to full inclusion of perspective, contribution and co-authorship. Though
researchers are open to the value of IQ, few take the initiative to fully appreciate and
understand its potential importance. As a result, the integration of IQ is more often directed at
a specific research question, and acknowledged with a sentence or as a manuscript citation
rather than approaching the Inuit-derived epistemology with more open questions and full
integration of unexpected or unanticipated observations with the recognition of an Inuit
contributor as an author, equal or expert. Suggested guidelines are helpful before, during and
after incorporating IQ (3).
Since Inuit post-colonial perceptions of scientists are understandably founded in
mistrust, researchers may not be seen sensitive to the same level of respect, reverence and
gratitude for the Arctic environment. Valued awareness of IQ, and recognition and
acknowledgement of Inuit insights and observations, will help scientific investigators reinforce
to their Inuit partners the importance of collaboration. Opportunities for discoveries of Arctic
science and, specifically, narwhal biology are greatly expanded through the collaborative
efforts of science and IQ (4, 5, 6).
IQ Adds to Cultural and Scientific Studies
IQ has benefited narwhal studies in multiple areas including migration, aggregation, dive
patterns, acoustics, integrative and organismal biology, evolution, ecology, conservation and
tusk function. Historically, publications from the 1700s to 1800s were primarily focused on the
narwhal as a curiosity due to its extraordinary and valuable tusk, which was worth more than
500 times its weight in gold. Tusks were also used as an antidote for potential poisoning of
kings and rulers, and its fascination for the art world was celebrated in works such as Flemish
tapestries, including The Lady and the Unicorn at the Cluny Museum in Paris and The Hunt of
the Unicorn at the Cloisters Museum in New York, which remain some of the most valuable art
pieces in the world. Though Inuit contributions are rarely mentioned in the literature, early
Norse experiences with the narwhal are surmised to be offered by Inuit hunters. Mentions of
the narwhal in 20th and 21st century literature switch attention to establishing whale harvest
quotas to maintain sustainable populations. There is a wide array of publications focused on
survey counts to establish population size. Studies of migration and aggregation, particularly
through electronic tagging, help support overall narwhal population estimates. More recently,
the biological literature has included genetic studies addressing biologic questions of diversity,
evolution, climate science, COVID transmission, and tusk sensory function.
Narwhal Migration and Population, Science and IQ Perspectives
A wide range for the global narwhal population has been cited in the scientific literature.
The current estimate of 175,230 is compiled from a Canadian Baffin Bay population total of
141,909 (7), 14,485 from the Northern Hudson Bay (8), and populations from Greenland
(including Eastern Greenland) of 6,444 and from Western Greenland of 14,392 (9). Yet in
2010, the total number of narwhal was estimated to be 80,000, with a variation between
58,000 and 86,000 (10). Population modeling currently projects declining future narwhal
populations (11) due to environmental changes associated with climate change indicators such
as sea ice decline and the associated increase of killer whale populations (12), and reduced
prey availability (13).
Inconsistencies in survey counts have been noted in the literature; the Admiralty Inlet
population in Canada was estimated in 2010at 18,000 (14), though documented at 35,000 justtwo years later (7). Population estimates have actually increased over time (15, 16, 17, 18).
Decreasing narwhal population numbers were also reported in Western Greenland (19, 20), as
well as studies showing signs of a species at risk (21). Results of the study affected Inughuit
and Greenlandic hunting quotas, since overhunting was attributed as a potential cause.
Uummannaq narwhal hunter Pavia Nielsen addressed the 2006 Inuit Circumpolar Conference
in Barrow, Alaska (Utqiagvik) to present Inughuit hunters’ observations about increasing
narwhal populations which contradicted scientific results. A study several years later (22)
concluded that low population numbers were attributable to survey methodology. Despite
results from the Marine Mammal Commission report in 2005 showing declining numbers of
narwhal translated to reduced hunting quotas for subsistence hunters, in 2012 the North
Atlantic Marine Commission Scientific Committee and the Joint Commission on the
Conservation and Management of Narwhal and Beluga confirmed that narwhal populations in
Western Greenland were sustainable.
Harvested narwhal reported from agencies in Canada and Greenland in 2015
concluded that 766 were harvested from Canadian Inuit communities (23), and 408 from
communities reporting in Greenland (24). In Canada, a moratorium on narwhal hunting and a
fishing limit set in 2015 by Fisheries and Oceans Canada and the Canadian Government was
the result of disputed population estimates used in setting narwhal harvest quotas. The
findings were challenged with threats of a lawsuit from Nunavut Tunngavik Inc. and the
Nunavut Wildlife Management Board representing Inuit hunters in the High Canadian Arctic.
Mixed results from scientific surveys were also questioned as a means to set harvest quotas.
Current difficulties with population estimates include: 1. weather conditions prohibiting
continuous surveys; 2. having a fixed point of reference, usually with one plane, when whales
may be appearing at multiple locations at the same time; 3. ice blocking or covered in the
inlets; 4. killer whales scattering narwhal groupings; 5. population mixing or philopatry
(narwhals returning to the same area); and, 6. added calculations that cannot be accurately
estimated from an aerial surface view, since narwhals swim in layers. There is thus a great
potential benefit to integrating more IQ in the survey process that includes population,
migration and aggregation studies. Future research will benefit from the active participation of
Inuit hunters, who can supply an additional source of population information that can influence
the accuracy of scientific population estimates. Inuit hunters have the advantage of being
spread out over the water and land in vast numbers, engaged in radio communication to
monitor narwhal sightings. More active participation will enable instances of multiple
populations appearing at the same time to be accurately counted, an issue that was presented
at the Inuit Circumpolar Conference in 2005. The circumpolar Inuit are a vast wealth of IQ that
can, and should, be more integrated into the scientific process (Figure 1). In many cases of
environmental and animal management, the Inuit offer additional observations that can
augment, assist and direct scientific studies.
IQ/Science Collaborative Benefits
Knowledge of narwhal biology has greatly benefited from collaboration with Inuit from
the High Arctic of Eastern Canada and Western Greenland (4, 25), including studies showing
the significance of IQ in understanding Arctic climate and environmental change (26, 27, 28,
29) Arctic wildlife management (30, 31, 32; 33, 34, 35, 36, 37), and Arctic marine mammals (6,
38, 39, 40). More specifically, authors have used IQ to describe the narwhal and its behavior
(5, 41, 42, 43, 44, 45, 46, 47, 48, 49), including hunters’ observations of seasonal
aggregations, migration and population, and anatomic variations of narwhal in the Canadian
Arctic and off Northwest Greenland (4, 5, 50, 51).Examples showing the benefit of IQ/science collaborations include recognition studies
of individual narwhal in a population through scientific observations of skin markings (52) since
scientific observations have limited use in identifying narwhals returning to a specific
geographical region. Inuit recognize individual narwhals, and can identify geographical regions
of individual narwhal by body, tusk morphology, and behavior. IQ is useful in better
understanding population admixture. For example, during a large “sassat” “sikujjivik”,
“sikujjaujut” (an ice entrapment caused by the formation of fast ice) in Pond Inlet in 2008, when
more than 1,000 narwhals were trapped, perished or harvested, Inuit recognized many of the
whales from a group in Clyde River, 410 kilometers south, and recognized by scientists (53).
As seismic testing had occurred close to the time of this event, speculation from Inuit was that
these whales were disoriented and traveled to Pond Inlet. Other factors contribute to changes
in migration and distribution, including climate change and global warming, with more open
water over a longer period; killer whale predation becoming more prevalent, and noise
pollution from commercial development and shipping, including mining and tourism (54). With
increased killer whale populations in ice-free regions over a longer time span, there is an
increased consumption loss (12) as narwhal lose their evolutionary advantage of a dorsal
ridge, allowing them to more easily escape below the ice or move to an area separated by a
large area of ice as compared to the large dorsal fin of orca preventing them from such areas.
Comparative dive times of narwhal recorded at 20 minutes, versus only 11 minutes for killer
whales, is another factor in narwhal survival. Future studies of migration and distribution of
narwhal populations can and will be advanced by integrating facial recognition software with
IQ, to better monitor changing migration patterns affected by climate, and other environmental
factors (55). Inuit hunters are sensitive to these changes, and can identify narwhal migratory
patterns and groups to other communities. In the case of climate change, some communities
which have long been associated with narwhal hunting have seen their populations decrease
or disappear, while other communities observe new or increasing narwhal populations (56).
Conservation and Anthropogenic Impact on Arctic Ecosystems
Additional environmental factors include the rapid detection and accumulation of
plastics in the Arctic ecosystem. Approximately 360 million tons of plastics are produced
globally each year (57), with 19 to 23 metric tons mismanaged and 90% transferred from land
sources to water (58). The Arctic Ocean is the last stop of the North Atlantic Themohaline
circulation, and is also influenced by the North Pacific carrying plastics that originate from
Southern latitudes to the Arctic, eventually infiltrating Arctic food webs of aquatic and terrestrial
systems (59). Microplastics, broadly defined as <5mm, are ubiquitous, and their small size
makes their source-to-sea impact dramatic in Arctic ecosystems, as they are easily
incorporated into multiple trophic levels of the food web. Added risk comes from the fact that
they can also easily bind heavy metals and POPs, persistent organic pollutants. Studies that
monitor and describe the impact of anthropogenic contaminants on narwhal through global
transport of ocean currents, increased maritime activity in the Arctic, and mismanaged waste,
will continue to provide valuable insights to government oversight agencies, and conservation
scientists about impact, adaptation and survival in this rapidly changing geographic region (60,
61).
Arctic fauna particularly are facing one of the most pressing conservation issues:
increasing and sustained ocean noise pollution generated from human activity (anthrophony),
which has come to the attention of the International Maritime Organization, shipping industry,
Inuit organizations, scientists and conservations experts. Noise propagation sources include
ocean commercial and tourism-based vessel engine cavitation, seismic testing and increasedArctic Ocean vessel traffic, as ice-free passages open pathways for both commercial and
tourism-related development. Statistical measurements of Arctic Ocean vessels can be
misleading, as the addition of 25% more vessels over a time period from 2013 to 2019, is more
accurately described by the distance traveled. For example, bulk vessels defined by the
Protection for the Arctic Marine Environment’s (PAME) Arctic Ship Traffic Data (ASTD),
established in 2019, showed an increase of 160% in the distance traveled, and an overall 75%
increase in all vessels. (62).
Discoveries of rich mineral deposits, gas and oil reserves have focused more attention
on harnessing Arctic resources, and thus has led to more commercial development off-shore
and additional transport shipping noise. Greenland is one example of rapid growth and
environmental concern from both commercial and tourism-based interests. Greenland has an
ecosystem with rich geo- and biodiversity. Its terrestrial and ocean environment (63) is home to
9,500 species (64), including narwhal, walrus, musk ox, caribou, Arctic hare and polar bear,
and 253 bird species (65, 66, 67). With developing economic, social and political interests, the
country faces critical choices that impact the approach to maintaining this rich biodiversity.
Though the International Ecotourism Society defines ecotourism as “responsible travel
to natural areas that conserves the environment, sustains the well-being of local people, and
involves interpretation and education,” Greenland’s rich deposits of minerals and rapidly
developing tourism market have attracted economic investors overlooking these priorities, and
once again reminding the Inuit of past colonial interests and values. Greenland has ceased to
be a formal Danish colony since 1953, though autonomy still has its memories of past Danish
colonization, including Inuit children being taken away from their homes and placed in an
orphanage in Nuuk in order to integrate into Danish society. Most were never reunited with
their families (68). Hunting grounds were taken away, and even the Thule American airbase
was built after an existing Inuit community was given just a few days to move (69). Interests in
harvesting rich natural resources highlight ongoing economic incentives and alternative
motives from cultural imperialism (70). If ecotourism is to be seen as a potential economic
opportunity, Greenlanders want to see these developments balanced with sensitivity and
respect for Inuit, Inughuit and Greenlandic values. Otherwise, future collaborations between
scientists and Inuit will be clouded by a lack of respect and the very premise set to “conserve
the environment” and sustain values of the Inuit.
Using the United Nations Sustainable Development Goals (SDGs) as a politically
established international guide, Goal 12 states “Responsible consumption and production,”
which questions methods that have been proposed and used for the exploration of natural
resources in the Arctic using seismic testing for example, since clearly the noise produced
impacts biodiversity, one of the necessary factors for Goal 14, to “Conserve and sustainably
use the oceans, seas and marine resources for sustainable development.” What needs to be
done? Follow both scientific and IQ agreed recommendations to protect the Arctic Ocean
environment, so that species like narwhal can better survive, adapt and thrive in their
environment. Adding an additional sub-target goal of reduced noise pollution would clarify the
importance of this environmental concern among those already addressed.
Narwhal are recognized as one of the most extraordinary marine mammals on the
planet, revered by the Inuit and the subject of fascination throughout history in art and science.
Since the writings of Albertus Magnus in the 1500’s, the whale, and particularly its unusual and
unique tusk, has captivated both aristocracy as a symbol of imperial recognition integrated in
sceptres and thrones, and science as an evolutionary challenge to understand the functional
significance for nature’s only straight, spiraled and asymmetric tusk, defying many of the
principles of expression and morphology of teeth. Studies of the narwhal tooth sensory organsystem (4, 71) are thus a useful model for the continued research needed in other sensory
organ systems. These include, but are not limited to, taste, smell, sight, sound and touch.
Combined with this approach are needed studies of narwhal physiology and anatomic
systems, including the skeletal, muscular, nervous, renal and urinary, respiratory, endocrine,
digestive, circulatory and cardiovascular, reproductive, and immune and lymphatic systems.
Narwhal anatomy and physiology explore extremes and outliers of evolutionary adaptation,
and future studies will contribute valuable insights into cetacean, as well as human and
mammalian, evolution. For example, understanding the digestive system may provide links to
why whales are carnivores when their evolutionary artiodactyl predecessors were herbivores,
including even-toed ungulates, ruminants, and other species. Why do narwhal possess the
most directed high frequency beam for echolocation? Why do narwhal have a unique fluke
design different from other whales?
Cetacean Evolutionary Background
As background, the remarkable evolutionary transformation of Cetaceans is notable
among all mammals, having originated from artiodactyl origins of even-toed ungulates over 55
million years ago during the Eocene era (72), and morphological adaptations that have
provided a successful transition from land to ocean (73). The fossil record is equally
astonishing in documenting the changes from the Eocene (56–34 Ma) that include
reorientation of the spine, reduction of hind limbs, movement of the nostrils posteriorly,
development and functional use for underwater hearing, and diverse pathways for feeding and
expression of tooth organ systems (74, 75, 76). Cetaceans classified in the Order
Cetartiodactyla include other groups without true hooves and without true ruminants, e.g.,
camel pig and hippopotamus. Studies of molecular genetics show that the hippopotamus and
whales share this common ancestor (77) even with disparate diet, habitat, physiology and
behavior. Divergent parvorders of Odontoceti (toothed whales) and Mysticeti (baleen whales)
have been established from the fossil record, and supported by molecular genetic study.
Toothed mysticeti had pre-baleen structures in the Oligocene Epoch, 24-34 million years ago,
and toothless mysticeti were prevalent dating back 30 million years ago to the recent past. The
evolutionary pathway for modern mysteceti began with toothed archeocetes, and then to
toothed plus baleen whales to extant baleen whales. This is also partially supported by
molecular genetic findings of inactive genes for ameloblastin and enamelin in extant
mystecetes. The evolutionary pathway for narwhal is more direct from ancestral toothed
whales. Yet, when examining tooth evolution for odontocetes, narwhal have adapted an
uncharacteristic tooth form (Supplementary Figure 1). Lineages leading to modern cetacean
families were present by the Middle Miocene. Balaenopteroidea, Ziphiidae, Monodontidae +
Phocoenidae, and Delphinidae began to diversify in the Early-to-Middle Miocene, Delphinoidea
(Monodontidae + Phocoenidae + Delphinidae) is well-supported with Monodontidae more
closely related to Phocoenidae, as noted in previous analyses (78, 79, 80, 81, 82, 83, 84, 85,
86) (Supplementary Figure 2). Crown delphinoids originated in the Early Miocene (x¯ =19.78
Ma; 95% CI: 18.81-20.76). Fossil lineages grouped in the “Kentriodontidae” have been tied to
the early diversification of Delphinida and Delphinoidea, but revision of this group is in process
(87, 88, 89). Both Crown Phocoenidae and Crown Monodontidae originated in the Late
Miocene. Additional investigation may link such diverse artiodactyl links of evolution as the
discovery of Arctic camels (90, 91).
Systems Approach to Cetacean and Narwhal Physiology
Whales have some of the most interesting biological adaptations of anatomy, physiologyand functional use. The systems approach to whale anatomy is thus useful in addressing
future studies of physiology and sensory function. The digestive system of the narwhal, as in
other cetaceans, is multi-chambered, similar to other herbivorious mammals including ruminant
herbivores, despite the evolutionary dietary adaptation to being carnivores. Preliminary
examination of their digestive system from the three distinctly different populations concludes a
differing foraging pattern (92). East Greenland subspecies prey primarily on capelin from the
pelagic ocean zone, whales from northern Hudson Bay on shrimp and halibut from the benthic,
and narwhals from Baffin Bay on both benthic and pelagic prey. The reproductive system is
comprised of internalized organs including breasts, teats, and penis. Whales and narwhals do
not have an internal bone in the penis to keep it rigid, a trait shared with sea cows and
humans. Whales have elastic tissue and do not need blood flow to keep rigid. Of skeletal
interest is the fact that whales still have a remaining pelvis despite no hind limbs, with functions
to stabilize the penis, control the birthing canal and assist in locomotion. Reproduction is tail-
first, equivalent to breach birth, so that the entire whale can emerge before taking a breath.
Future studies may provide insight into the genetic shift to create this reverse. Whales do not
have lips but rather wrap their tongue around a tube that dispenses the milk. The
muscleoskeletal system includes adaptation of the artiodactyl limbs, such as variable flipper
forms with narwhal being more paddle-shaped as opposed to square shaped in right and
bowhead whales; falcate in porpoises, dolphins and rorqual mysticetes; triangular in some river
dolphins; elongated on finned pilot whales, and very long on humpback whales. Cetacean
flippers can move in multiple planes and have the same humerus, radius and ulna, carpals and
phalanges morphology as humans, with an added hyperphalangy for flipper extension
(Supplementary Figure 3). Their hind limbs undergo a gradual reduction as seen in the
archeocete Basilosaurus, with rudimentary hind limb remnants, compared with narwhal having
no evidence of hind limbs and a remnant pelvis. Cetacean spinal movements are complex and
flexible including circular movements around an axis “yaw” horizontal plane, pitch vertical
plane-like yaw but rotated 90 degrees, and “roll” over the long axis of body, tipping sideways
transverse plane. Narwhal have a fluke design that is consistent among most whales, though
they have one acute departure, a concave leading edge without sweepback. Males have high
efficiency at high speeds and females have increased lift and thrust at low speeds. The lack of
sweepback in males and increased efficiency may be associated with the drag of the tusk, and
female fluke design is more efficient during deeper dives, which are more common for them
(93) Narwhal skeletal anatomy is best described through a series of anatomical plates (Figure
2) showing developmental and morphological adaptation with tusk expression and sexual
dimorphism (94). The circulatory and cardiovascular system is marked by veins that surround
arteries at periphery for warming, and likewise cooling veins close to arteries to release cool
temps for sperm mobility. Both veins and arteries can dilate or constrict for another layer of
thermoregulation. Added thermoregulation is compensated for with thin blubber, a non-
compressible insulator for whales, in the areas of tail flukes, flippers and genital area, to
regulate heat which can interfere with reproduction and sperm mobility. The respiratory system
of odontocetes is identified with one blowhole in odontocetes and two in mysticetes. Blowholes
in archeocetes are located more anteriorly, while those in more modern cetaceans migrate
back dorsally. The shape of blowholes is unique to each whale, and thus species identification
can be made from a blow hole breadth.
Evolutionary Adaptation of Sensory Organs
Sensory organs in the narwhal help elucidate evolutionary adaptation by exploring the
extremes and constraints of functional use. Limited vision, and greatly expanded auditoryfunction are examples of these extremes associated with cetacean sensory organs. The sense
of sound is recognized as one of the most important sensory functions for narwhal. Mysticetes
emit low frequency sounds from the larynx and are generated from air rushing past the vocal
folds causing vibrations, and are associated with communication. Only odontocetes use sound
for navigation and prey tracking. Tusked narwhals especially need echolocation to navigate
thin leads in the ice. Sound vocalizations are produced and emitted from phonic lips and
filtered through fat bodies in the melon. Returning sounds are received by fat in the lower jaw.
Sound reception from bone conduction is not likely, as the narwhal ears are separated from the
skull. Narwhals have the most directional echolocation beam used for orientation and foraging
for any cetacean (95). During a routine hydrophone recording in 2007 at Qakkiat Point in Arctic
Bay Nunavut, an investigator positioned in the water approximately 6 feet away from the tip of
a male narwhal being tagged for research, experienced a momentary numbness in the right
leg. Hydrophone recordings documented the directed beam and its characteristics (Figure 3).
Hair is another mammalian trait that may be useful as a sensory stimulus between a calf’s lips
and a mother’s genital area to extrude her teats for milking. Hair appearing near the narwhal
eye may also be involved with sensory signal transmission about currents during resting
periods. The most complete sensory organ system studied in the narwhal is the erupted tusk
and tooth organ system (71). (Figure 4). Tusk function has been shown to be primarily sensory
and modeled after Brännström’s hydrodynamic theory of tooth sensitivity Evidence includes: 1.
the presence of sensory genes Dlx2, FAM134B, NGFR and TFAP2A being highly expressed in
narwhal pulpal tissue when compared to surrounding tissues; 2. neuronal markers CGRP and
Substance P in pulpal tissue with important roles associated with physiology and pathology
(96); 3. patent dentinal tubules and channels within cementum tusk covering formed by
Sharpey’s fibers, allowing direct communication between the tooth sensory system and
external ocean environment; and, 4. “in vivo” neurophysiological tusk perception to differences
in high salt- and fresh-water solutions. By examining anatomy, histology, physiology, diet (97),
genetics, and in vivo experiments for sensory confirmation, the research has generated the
most complete understanding of narwhal sensory function documented. Primary sensory
function is likely linked to use in sexual selection and reproductive fitness, and most likely
“mate choice” or intersexual selection (71, 98). Secondary considerations include establishing
male hierarchy (71, 99, 100, 101, 102). Other theories include “male-male rivalry” or
intersexual selection (101). New studies of position-resolved structural and mechanical
properties of narwhal dental tissues by Fourier-transform infrared reflectance
microspectroscopy with 100x100 µm to 200x200 µm spatial resolution illustrate unusual
properties of tusk strength and flexibility. Young’s Modulus and microhardness were measured
using nano indentation with 200 x 100µm spacial resolution. Mineral to collagen ratios showed
decreasing values from tip to base and from the inner pulpal wall to external surface (103).
(Figure 5) (Supplemental Text). Results from this study help formulate an estimate of narwhal
tusk flexibility in a 2.5 meter length to have the ability to bend in all directions by 12 degrees.
Additional studies will advance our understanding of unique narwhal evolutionary adaptation
and functional tissue characteristics that may have biomimicry applications in modern
medicine.
Narwhals and whales in general are some of the most intelligent animals on the planet
as measured by brain size to body size. Their brains contain more grey matter and less white
matter which may relate to added information processing, and future studies will help examine
narwhal intelligence and processing.
Paleontological studies of biologic structures can guide phylogenetic analyses. For
example, investigation of fetal membrane and uterine structures determined the artiodactylorigins of narwhal as early as 1937 (104). Synapomorphy described as shared traits from a
common ancestor represent another method of understanding phylogeny. Evolutionary
adaptation of mammals from different environments is illustrated by the comparison of the
paraxonic foot of cetaceans, hippopotamus and humans, all sharing the same axis between
the third and fourth digits (105). Homologous structures also suggest synapomorphy. In the
case of narwhal tusk microstructure, the unique patent dentinal tubules from the ocean
environment to the dental pulp is present in the tusks of Odobenoceptops (Figure 6). By
integrating biologic studies of organ systems with genetic analysis through studies of narwhal
genomics, phenomics, transmission genetics and phylogenetics, a better understanding of
narwhal biology will be attained.
Genomic Comparisons in Cetacean Phylogenetic Studies
Phylogenetic comparisons benefit from increased variable base pairs, and so highly
resolved genomes of narwhal and beluga can better determine their inferred relationship and
shared Monodontidae family. By analyzing whole genomes with an estimated 20,000 genes,
sampling errors are less likely to be included in results. Among the proposed comparative
studies of beluga and narwhal should be genome content including the order of genes along
the linear length of the chromosomes, the orientation of the genes or direction in which the
coding sequence is read compared with other genes, and the mere presence or absence of
genes in the genome as has been initiated in the studies by the Zoonomia Consortium at the
Broad Institute (106), and gaining insight into mammalian diversity by tracing backward to an
ancestral genome (107). Examination of the sequence not containing genes or encoding
proteins will also add insight to the evolutionary path, describing whether genes are evolving
together and how changes can affect the biology of the species. Portions of the genome that
have no genes but contain regulatory elements and non-coding RNAs can help determine
critical points of evolutionary adaptation.
Narwhal biology is strongly linked to Arctic climate. Narwhals survived ice ages during
the last 2.5 million years, including the cooling cycles of the “little ice age” during the Holocene,
spanning the last 11,700 years. Narwhal sediment remains in the North Atlantic from this era
indicate a similar distribution to today’s populations. Molecular signals from narwhal and
beluga show a common ancestor back 6.3 million years before the onset of major cooling
cycles. With global warming, narwhals should be able to adapt as they did during the last
interglacial period associated with minimal ice and warming temperatures 125,000 years ago,
through survival during the Anthropocene has the added element of human interaction.
Linking Genetics with Narwhal Disease Risk
Genetic studies have predicted and will continue to predict viral infection rates for
narwhal and other Arctic cetacean species. Collaborative efforts to engage Inuit hunters in
monitoring unusual symptoms of cetaceans can assist early detection and diagnosis of water
or airborne diseases. For example, studies of the Sars-CoV-2 transmission to animals
demonstrated the high susceptibility and potential transmission to cetaceans, as they shared
with humans most of the ACE2 spike protein binding sites for the virus. High Arctic
communities were affected by SARS-CoV-2 transmission, and thus future viral transmissions
for high latitude communities and ecosystems remain concerning. Arctic mammals are integral
components of high latitude ecosystems and may become important in a chain of transmission
with other Arctic mammals. Toothed whales appear uniquely vulnerable to developing illness
from SARS-Cov-2. These species have a “high” binding propensity for the virus due to a very
similar amino acid sequence of ACE2 (the receptor site for SARS-CoV-2 binding) compared tohumans (108). Of the 25 amino acid residues that are associated with the viral spike protein
binding site on ACE2 in humans, cetaceans share 22. At the same time, toothed whales have
demonstrated a limited immune resistance to prevent infection from viruses with functional loss
of the GTPase genes myxovirus1 MX1 and MX2, thus potentially manifesting severe disease
outcomes (109). A Bronx Zoo tiger exhibited COVID19 symptoms and disease (110), yet this
species predicted ACE2 binding capacity was only “medium” relative to humans (111). There is
an urgent need to understand disease reservoirs and the possibility of infection in non-human
species. Gammacoronavirus has already been found in a beluga whale (112) and bottlenose
dolphins (113), and a suspected alphacoronavirus was found in harbor seals (114). All are
associated with respiratory diseases, though the cellular receptor used by these viruses to
mediate cellular entry was not known. Prior epidemics of PDV distemper virus in harbor seals
in 1988,and 2002 accounted for over 50,000 deaths, and remind us of viral impact in the ocean
environment (115).
Beyond its role in mediating cellular entry of SARS-CoV-2, ACE2 is of special
significance to the cardiovascular biology of toothed whales. Angiotensin-converting enzyme
(ACE2) plays a role in blood pressure control by converting a vasodilatory peptide (AngI) into
the vasodilatory AngII. Vasoregulatory peptides such as angiotensins act on smooth muscle in
the vasculature to change the diameter of arteries and regulate blood flow. The marine
mammal dive response permits these animals to dive for extended durations and to extreme
depths. A key element of the dive response is blood pressure regulation; heart rate falls during
submergence and must be balanced by profound vasoconstriction in the peripheral
vasculature to prevent a dangerous drop in central arterial pressure. Evidence for positive
selection has already been noted in cetacean ACE2, and this has been linked to adaptation of
the renin-angiotensin system, important for blood pressure control as well as salt balance in
the marine environment. Genetic capabilities have generated a new pathway for understanding
and predicting the changing ocean environment, anthropogenic variables and their potential
threat to narwhal and other Arctic species.
Advancing The Process of Data Collection
The methodology and process of data acquisition has changed dramatically over the
past 50 years from traditional collection of specimens to remote imaging and sensing. The
definition of remote includes technologies that are brought to observational sites, and continue
to gather data after one leaves the site, and fixed technologies like genetic sequencers or CT
scanners that are now mobile and can be remotely brought to a sample site. Advances in
these remote technologies have been transformational in data collection, and onsite analysis.
Many of the technologies used to gain observation and knowledge in the Arctic benefit most by
being there over prolonged periods of time. Due to expense, remoteness, weather and ice
conditions, darkness, logistics, scientists typically are only able to remain in base camps, boats
or other field sites for limited time periods. Thus there is tremendous benefit to remote
technologies that can continue to collect data sets over more prolonged periods of time.
Examples of remote imaging, and sensing include but are not limited to, cameras (116), motion
detection video, light scanners (117) (Supplementary Figure 4), advanced drones with longer
programmable flight times (118, 119), mobile Position Emission Tomography, Computerized
Tomography PET/CT scanners, augmented reality, and artificial intelligence. Whale tags and
remote sensing devices placed on whales have been used extensively and successfully in the
Arctic and on narwhal to measure dive depths (120, 121); patterns, migration and distribution,
and orientation (89); acceleration and sex-specific movement (122); seasonal diet selection
and foraging behavior, seasonal habitat identification, salinity, temperature, sound recordings,navigational and communication (123, 124, 125); and heart rate (126).
Hospital grade equipment typically requiring samples to be brought back to institutions
for analysis have also been housed in waterproof casings for onsite analysis of brain activity
and heart rate on narwhal for the first time in the Arctic (71). Through the use of these new
technologies, and applying traditionally large instrumentation in a mobile format for remote field
use, scientists have new technology, ease of analysis, and remote sensing data collection
available.
Inuit observers and the use of IQ is the most valuable remote sensing tool available to
scientists. As astute observers of the natural and physical world, they are uniquely connected
to their environment by survival (127). Because they hunt over a longer seasonal period as a
result of increasing ice-free areas and climate change, and live and observe extensively on the
water, they are the most reliable remote sensing collectors available to scientists, and are able
to provide invaluable information on narwhal behavior and habitat. For example, skin molting
had not been reported for narwhal as a potential reasoning for their migration into fresh water
inlets until a report (128) from Inuit hunters in Greenland witnessed the thin gauze-like skin
molting of summering narwhal off of Qaannaaq. Hunters also observe the extremes of survival
and thus dive duration times reported in the scientific literature of 25 minutes (129) are almost
doubled at 45 minutes by Inuit observations during hunting.
Conclusion
Though many research efforts have focused on the narwhal, and more broadly on Arctic
biology, management of Inuit hunting practices and quotas, and studies of the ecosystems,
there remains a need for ongoing studies that layer IQ, social, political, conservation, remote
sensing and science together. The “pristine” Arctic has already succumbed to environmental
disruption during the Anthropocene through pollutants and mismanaged waste, increased
noise from seismic testing and natural resource harvesting, commercial and tourism boat
traffic, longer shipping routes in an increasingly ice-free Arctic, microplastics and climate
change. Though narwhal populations are currently stable and sustainable, there are increasing
environmental pressures and stressors that are influencing and potentially disrupting their
evolutionary path. The increased and rapid rate of these changes outweigh any political
capacity to address them, and so we must engage the Inuit in active monitoring and
observation that may prove useful to balance the environmental variables for survival so that
narwhal can continue their peaceful place in the Arctic ecosystem. Though scientists have new
technologies to address remote sensing and imaging, and powerful analytic instruments, tools
and technologies, perhaps their most valuable remote imaging and sensing instrument are the
Inuit themselves, careful, consistent and accurate observers of nature. Large systems-based
teams of researchers benefit from valuable new research tools combined with hundreds of
years of observational information collected by Inuit and stored as IQ and Isuma.
