Description of Narwhal (Sea Unicorn) from the Red Book

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The narwhal also has a second name; it is called the sea unicorn, and this designation is not accidental. These animals have an unusual, unique appearance that amazed the discoverers and continues to amaze to this day. These are smart and graceful animals that live in the coldest parts of the planet.

Description

Narwhals primarily live in packs. Flocks range in size from 3-8 individuals, and sometimes number up to twenty animals. Males and females with cubs gather separately in them. Narwhals constantly communicate using sharp sounds in the form of:

• moans;
• mooing;
• clicking;
• gurgling.

A distinctive feature of the narwhal is that the male has a long horn or tusk, approximately three meters long. The tusk horn is hard, but quite flexible.

Narwhals live almost the entire year in the waters of the Arctic zone. They migrate in accordance with the movement of ice: in winter they move to the southern zone, and in the summer season to the northern zone.

In the summer, the narwhal lives in deep-sea places, and winters in the water spaces between the ice. When the ice hole freezes, the male destroys the ice barrier by striking with his back or tusk.

Narwhals have a lifespan of 35-56 years.

Communication and perception

Narwhals communicate acoustically. This species of toothed whale is capable of producing two different types of sounds:

• pulse. This type of signal typically ranges from 12 to 20 kHz. As the name suggests, it is a short, rapid sound or click. They are used by narwhals as a kind of echolocation, allowing them to effectively detect and catch prey. This type of sound is also used for spatial orientation and likely helps narwhals stay together during migration.
• whistling. Unlike a pulsed sound, a whistle is a longer signal with varying frequencies that is probably used primarily for communication. These sounds range from 300 Hz to 10 kHz.

When studying the tusk of a narwhal, about ten million nerve endings were discovered. This leads researchers to believe that the tusks have a sensory function. In 2014, scientists at Harvard Medical School found that the narwhal's heart rate increased and decreased when the tusk was exposed to high or low concentrations of salt in ocean water.

Appearance

The narwhal has a round head, not very large, with a protruding frontal part. The muzzle and nose are rounded. The whale does not have a dorsal fin, but there is a ridge-like formation on its back. Its length is 5 centimeters, and its height ranges from 60 to 90 centimeters.

Adults are dark gray or brown on top and lighter underneath. The entire body is covered with a spotted pattern.

The animal has no lower teeth. The upper jaw is equipped with two teeth. The male's left tooth passes through the lip and continues as a straight tusk. The tusk has a spiral pattern.

The tusk can have a maximum length of three meters and reach ten kilograms in weight. There are cases when a tusk grows from the right tooth, but rarely.

Females generally do not have tusks, but sometimes they do have tusks. The tusk is strong and flexible, it can bend in any direction, but does not break. The end of the tusk is polished, and the part closer to the head is entangled with algae. The internal cavity of the tusk-horn contains the endings of nerve cells and blood vessels.

The tusk is used by the narwhal for the following purposes:

• to attract females during the mating season;
• for measuring temperature and frequency of electromagnetic waves;
• as a club for prey or defense.

Behavior

The narwhal is a social animal and is usually found in schools of six to twenty individuals, although most groups tend to number between three and eight individuals. Smaller groups usually gather during the migration season to form a flock of hundreds or even thousands of individuals.

Narwhals remain in close proximity to the ice throughout the year. There are various hypotheses about the main functions of the tusk. Perhaps males use it for competition. It can also be used to obtain food. Since most females do not have a tusk, the most likely assumption is that these are secondary sexual characteristics.

Dimensions and weight

Male narwhals have a body length of approximately 470 centimeters, while females have a body length of 400 centimeters. The average weight of males is 2.5 tons. Females are much smaller. Their weight is about 900-1000 kilograms.

One third of the narwhal's mass is fat, which serves as reliable protection from the cold.

Where do they live?

Narwhals are inhabitants of the harsh northern region. They live:

• in the Arctic seas;
• in the Arctic Ocean;
• off the coast of Greenland;
• in the northern Canadian Arctic archipelago.

Several small groups have been recorded in the northeastern part of the coast of Franz Josef Land and north of Wrangel Island.

The modest charm of a male narwhal

People have enjoyed traveling for a long time. Things also traveled with them, sometimes traveling much longer than their owners. Archaeological evidence suggests that even in prehistoric times there was something like primitive trade, the objects of which, passing from hand to hand, often ended up very far from their place of origin. Archaeologists have not been surprised for a long time by the finds of tropical shells living in the Red Sea or the Persian Gulf, somewhere in northern Europe. Even in those times when the means of communication were imperfect and the speed of travel very slow, products of human hands and objects of animal origin gradually spread to all directions of the world.

It must be assumed that quite a long time ago, gifts of nature from the Far North began to penetrate into Europe. Among them were long pointed tusks, up to three meters long, belonging to an animal unknown to Europeans. Did they not mark the beginning of the legend about horned horses - unicorns, so widespread in the Middle Ages that these fantastic animals even ended up on the coat of arms of Great Britain? All sorts of fantastic qualities were attributed to the horn of this creature; They assured that it could protect its owner from the effects of poison.

Now everyone knows that the unicorn really exists, but it is not at all like a horse. The real unicorn belongs to the order Cetacea, a marine mammal typical of the Arctic Ocean and the North Atlantic. Among zoologists it is known as the narwhal or, in Latin, Monodon monoceros. The literal translation of the scientific name into Russian looks strange - “one-toothed unicorn”. From an anatomical point of view, this is a tautology, because the narwhal’s horn is nothing more than a huge, overgrown left tooth, as expected - with a dental canal inside. And it is not located on the animal’s forehead, but grows from the upper jaw. It is interesting that the right tooth normally remains short, but there are no teeth at all on the lower jaw of the narwhal. This animal has only two teeth. A characteristic feature of the narwhal tusk is the spiral “cutting” of its surface, as if turned on a machine. According to zoologist A.G. Tomilina, this cutting “is formed over a long period of time: during the operation of the tail blades and the forward movement of the animal, the tusk, resisting the water, very slowly rotates around its axis, and the uneven walls of the hole cut spiral grooves on the surface of the growing tusk.”

Only male narwhals have such a magnificent decoration. Females of this species also have two teeth, but they are short, completely hidden under the gums and not visible from the outside. Compared to the largest representatives of cetaceans (blue whale, sperm whale), the narwhal is very small; The animal’s body length rarely reaches six meters (these are males, and females are about a quarter smaller). In this case, the size of the tusk can be 2.6 meters (for females - a maximum of 33 centimeters).

European naturalists learned about the narwhal itself much later than about its tusk. Early ideas about his appearance were far from the truth. Usually they tried to make the narwhal resemble a large fish, with a dorsal fin, scales and a fish-like tail. However, already two centuries ago, zoologists quite accurately described and depicted this animal:

This is how the ideas of European naturalists about the appearance of the narwhal changed, from a semi-fantastic image of 1645 to a completely accurate drawing published by William Scoresby in 1820. Images are taken from open Internet sources.

And, of course, researchers have always been interested in the question of why the male narwhal got such an ornament in the form of a long and heavy tusk. Horns, tusks and similar formations on the body of animals are always an “expensive pleasure” from the point of view of the body’s energy. Heavy growths on the body create a considerable burden on the body, so their existence requires very compelling reasons; they must bring significant benefits to their owner, which exceeds all possible losses and inconveniences.

The purpose of the narwhal tusk was of interest not only to scientists, but also to writers. Jules Verne writes the following in his novel Twenty Thousand Leagues Under the Sea:

“The common narwhal, or unicorn, often reaches sixty feet in length... the narwhal is armed with a kind of bone sword, a halberd, as some naturalists call it. This is a huge horn with the hardness of steel. Traces of wounds have been found more than once on the body of whales, which the narwhal always attacks with success. It happened that fragments of narwhal tusk were extracted from the wooden hulls of ships, which they pierced through, like a drill drilling through a barrel. The Museum of the Faculty of Medicine of Paris has a tusk two meters and twenty-five centimeters long, which at the base reaches a circumference of forty-eight centimeters.”

So, first of all, the tusk was considered as a weapon of defense or attack.

From a zoological point of view, the presence of a well-developed tusk only in male narwhals clearly shows that this trait must be associated with some specific “male” functions, be it protection from enemies or competition for a female. Naturalists guessed about this two hundred years ago. This is how the English explorer William Crosby, the son of a whaler, who made several voyages to the Arctic seas on board a whaling ship, reasoned in 1820:

“How the narwhal uses its tusk is unclear. The tusk cannot be a tool for obtaining food, otherwise not a single [animal] would be deprived of it; perhaps it is not needed for protection either, because otherwise females and young narwhals would remain vulnerable to strong enemies and only the males would have such a wonderful protective device. Dr. Berkeley, with whom I spoke on this subject, is of the opinion that the tusk is almost exclusively a distinctive sexual character, similar to those found in other animals."

It seems that Crosby considered the narwhal "horn" to be something of a secondary sexual characteristic, not playing a particularly important role in the life of the animal. True, he admits that sometimes this “manhood” can be useful:

“From the fact that the end [of the tusk] is always smooth and clean, and the rest of the part is uneven and dirty, and especially from the fact that finds of broken tusks are known ... it cannot be considered incredible that [the tusk] is used to pierce thin ice to ensure the ability to breathe without going into open water. But I believe that it is not used, as many authors assert, for obtaining food from the bottom of the sea; the fact is that these animals are often found in deep seas, where the enormous pressure of the water column existing at the bottom would not allow them to exist.”

Modern zoologists note that now, exactly two centuries after Crosby, it is not known exactly why the male picked the tusk. The hypotheses put forward over the elapsed time are called the narwhal horn:

1. A means of protection against enemies;

2. Tool for breaking ice;

3. An “argument” in the relationships between males when fighting for a female and building an intra-group hierarchy;

4. Acoustic probe;

5. A tool for digging;

6. Body stabilizer used in swimming;

7. Device for thermoregulation;

8. Chemical sense organ (remember that this is a real tooth, equipped with blood vessels and nerve endings through which information is transmitted to the brain.

Cross-section of a narwhal tusk. It can be seen that it has a typical “dental” internal structure, but there is no tooth enamel. According to Nweeeia et al. (2014), as modified.

And so on. I did not list all the hypotheses, focusing only on the most plausible ones. Stories of narwhals attacking the sides of wooden ships with their horns or driving their horns into the bodies of whales seem to be mostly classified as "hunting tales."

Testing all these remarkable assumptions is greatly complicated by the fact that narwhals do not take root well in captivity, and field observations of their behavior are very limited. These animals spend much of their time hidden under sea ice, and little is known about what happens to them there. However, some of the hypotheses can be tested using narwhal tusks available in museum collections. By examining the relative sizes of these giant teeth, we can draw certain conclusions about the role they play in the lives of male narwhals.

This is exactly the kind of work recently done by a team of researchers from the US, Brazil and the UK, who determined the tusk sizes of 245 adult male narwhals caught off the coast of Greenland between 1983 and 2018. When the growth rate of the tusks was compared with the growth rate of other body parts, it was found that narwhal tusks grow in size disproportionately quickly (in scientific parlance, this is called hyperallometry), faster than would be expected for a “simple” body part. It turns out that the narwhal “horn” is a very complex part of the body.

In order to explain the fact they discovered, the researchers resorted to the concept of sexual selection. This is one of the theoretical ideas put forward by Charles Darwin when he created his theory of evolution. An idea that was supported by some experts, but sharply criticized (and continues to be criticized) by others. Thus, the outstanding Russian ethologist (animal behavior specialist) Evgeniy Panov published an entire monograph criticizing Darwin’s idea, entitled “Sexual selection: theory or myth? Field zoology versus armchair knowledge.” Others, on the contrary, consider it very useful and explains many natural phenomena.

To understand the meaning of sexual selection, it is enough to remember the male peacock with his luxurious and colorful tail. Strictly speaking, such a bulky decoration in nature causes a lot of inconvenience. You can’t sit on every branch and you can’t hide from every enemy, and dragging a heavy tail behind you is also probably not an easy task. When Darwin formulated his theory of natural selection, the existence of the peacock's tail and similar traits seemed a big problem. If a tail potentially poses a threat to the life of its owner, then why didn’t peacocks go extinct or develop a smaller tail during evolution? Darwin suggested that when peacocks reproduce, the choice of sexual partner is made by females, who are much more modestly colored. In their eyes, a luxurious and lush tail seems very attractive, so the male with the largest tail had a greater chance of starting a family and producing offspring, which means that the genes responsible for the appearance of peacock decoration also passed on to subsequent generations, and everything started all over again. From an evolutionary point of view, the opportunity to leave offspring, and as numerous as possible, is the “reward” for the inconvenience and sometimes fatal risk to which the elegant male peacock is exposed. And this reward turns out to be more valuable than the chance of dying young in the claws or teeth of a predator.

Let's try to apply this logic to a narwhal tusk. Statistics show that the larger the male, the relatively larger his tusk. Scientists have suggested that the tusk serves as a kind of signal in relationships between males. As if from afar, he says to his rivals: “I’m bigger than you, it’s better not to interfere.” This is why it is “more profitable” for a male to grow a “horn” as long as possible, and this is why this sexual characteristic grows at an unexpectedly high speed. All possible inconveniences caused by a long and heavy “decoration” are more than compensated for by the advantages of such an alarm.

Here we need to turn to another aspect of the behavior of social animals. Everyone knows that in many species, during the breeding season, males engage in fights and fights for the possession of females. This is especially typical for “harem” animals, in which a male can have not one, but many females, leaving other rivals with their noses. In such a game, the stakes are the highest, so often mating games take on the character of genuine duels, sometimes with a fatal outcome. But here another calculation comes into play. From the point of view of the well-being of the entire population or species, it is not very good if strong and healthy males waste their energy on such massacres, and even with a high risk of death. Therefore, in many species, real battles are replaced by ritual ones. The rivals threaten each other, demonstrate decisive poses, and also try in every possible way to show their strength and body size. Thus, very often it does not come to a fight at all. After a series of such psychic attacks, one of the opponents usually decides that it’s not worth getting involved, “and I didn’t really want to,” turns and leaves. This has a deep biological meaning. Intraspecific struggle is useful when, as a result of competition between males, only the most successful are allowed to reproduce. But it becomes harmful if there is a high risk of serious injury or death. Therefore, such ritual battles are a kind of compromise between two trends. They are also completely common among people, because we humans are also social animals and also compete with each other, and not only for having an attractive sexual partner. Once upon a time, in the old days, these ritual battles took the form of knightly tournaments; now they are embodied in sports competitions, as well as all kinds of ratings, which modern civilization is so inclined to compile.

From the few field observations of the behavior of male narwhals, it is known that they have “comradely” meetings, in the presence of females or without them, where the animals seem to compare their tusks. Ethologists call this form of behavior “tusking” (can be translated as “tusking” or “tusking”).

Two male narwhals measure the length of their tusks in the presence of a female. This is called “tusking”, “tusking”. According to Graham et al. 2019, with changes.

True, examinations of the tusks and body surfaces of animals show that physical collisions still cannot occur. Males have much more scars and damage on their heads than females or young animals. Broken and damaged tusks are also very common (their frequency reaches 60%). There are known cases of narwhals being caught with broken tips of the tusks of their relatives stuck in the bones of the skull. It seems that the males periodically have to use their tools. This also explains the maximum size of the “horn”. It cannot be too long because of the danger of breaking during a combat collision. Therefore, “extra-long” narwhal tusks are not found in nature.

It cannot be ruled out that female narwhals somehow evaluate the size of the tusks and draw their own conclusions about the qualities of their owners. If we attribute some semblance of rational logic to this, then the female may think like this: “If this male with the greatest decoration is able to grow and wear such a thing, then he is probably very, very powerful and hardy. And I like it!” (In old books you can read about tusks weighing “almost a pound”, and this, after all, is almost sixteen kilograms). We still know very little about the intricacies of choosing a sexual partner in narwhals, but it is not at all excluded that a long tusk has the same magnetic effect on narwhals as the large tail of a male on a female peacock.

The zoologists who participated in the study I described emphasize that the use of tusks in the reproduction process does not at all exclude other functions of this organ. It may well be simultaneously used in perceiving the environment and even in obtaining food. But this can only be speculated about. The narwhal, a typical animal of the northern seas and still numerous (the International Red Book classifies it as a species “not of particular concern”), is still completely insufficiently studied. Among the future directions of research, scientists name observation of narwhal herds using unmanned aerial vehicles. The use of such tools could significantly expand existing understanding of the behavior and social relationships among Arctic unicorns.

Author:

Vinarsky Maxim Viktorovich, Doctor of Biological Sciences, Professor, Head. Laboratory of Macroecology and Biogeography of Invertebrates at St. Petersburg State University and chief researcher at the St. Petersburg branch of the Institute of the History of Natural Science and Technology of the Russian Academy of Sciences.

The following publications were used in preparing the essay:

Tomilin A.G. 1962. Cetacean fauna of the seas of the USSR. Keys to the fauna of the USSR, published by the Zoological Institute of the USSR Academy of Sciences. M. Issue. 79. 212 p. https://ashipunov.me/shipunov/school/books/tomilin1962_kitoobraznye.djvu

Graham ZA, Garde E., Heide-Jørgensen MP, Palaoro AV 2022. The longer the better: evidence that narwhal tusks are sexually selected. Biology Letters, 16: 20190950.

https://dx.doi.org/10.1098/rsbl.2019.0950

Nweeia M. et al. 2014. Sensory ability in the narwhal tooth organ system. The Anatomical Record, 297: 599–617. available for free download at: https://anatomypubs.onlinelibrary.wiley.com/doi/epdf/10.1002/ar.22886

Scoresby W. 1820. An account of the Arctic regions with a history and description of the northern whale-fishery. Edinburgh: Printed for A. Constable & co. Vol. 1. 551 pp. The publication is available at: https://www.biodiversitylibrary.org/page/9707302

Lifestyle

Narwhals usually form schools. They can contain 7-10 animals. But there are also single individuals.

In the winter cold, the narwhal escapes by diving to great depths, up to 1500 meters. Periodically, it floats above the water surface to swallow air, then descends again into deep waters. During the day, the narwhal has to make up to 25 dives. The animal dives vertically, this allows it to achieve greater speed. Also, a thick layer of subcutaneous fat protects the animal from low temperatures.

In the spring-summer season, narwhals live at shallow depths of up to 300 meters. Their food source is pack ice. And in the fall, narwhals migrate to the southern regions, located at 65-70 degrees north latitude.

What does a narwhal eat?

Photo: Narwhal, or sea unicorn

The physiology and lifestyle of narwhals allow them to become successful predators.

The narwhal's daily diet includes:

• deep-sea small fish - they prefer the most boneless, “soft” fish;
• mollusks, including cephalopods - octopuses, cuttlefish, squids;
• crustaceans;
• various northern fish: halibut, cod, cod, red snapper.

Narwhals usually hunt at depths of up to 1 km, although they prefer not to go below 500 meters. If a flock has not had food for a long time, they do not experience discomfort from this, but feed on their fat reserves. Narwhals have never been found emaciated or starved to death.

They search for food using echolocation. The sound is repelled by objects, among which narwhals recognize fish or other possible prey. They attack a school of fish together, using their moving necks to capture as much food as possible.

If the prey is single - an octopus or a squid, then the cubs and nursing females feed first, then the older females, and only at the end do the males eat. Narwhals spend all their time searching for food.

Like beluga whales, the narwhal's teeth have the ability to suck up water and "shoot" a long stream. Narwhals actively use this ability to get octopus or crustaceans out of narrow crevices or to suck small fish into their mouths.

Reproduction

Mating in narwhals occurs from March to May. Between males, a showdown occurs during the mating season. The winning male creates a small harem around himself and protects it from rivals. Copulation occurs with their stomachs in a vertical state. Cubs are born from July to August of the following year.

Pregnancy in a female lasts approximately 15 months. The female reproduces offspring at intervals of two to three years. Usually one baby is born, but rare cases of twins have been observed.

The baby whale is born forward with the tail part of the body. As soon as the baby is born, the female immediately pushes him out of the water. He gets his first breath of air.

A newborn narwhal's body has an average length of 1.6 meters and weighs 80 kilograms. Subcutaneous fat is 2.5 centimeters thick. The baby's skin is colored grayish-bluish. During the first days of life, the cub is constantly near the mother. Then the female can leave it for a while on the surface of the water to absorb a portion of food.

The duration of feeding the cub by the female is 20-24 months. After the end of the lactation period, the cub leaves the mother and joins the youth group.

Physical and sexual maturity in males occurs at the age of eight, and in females it is formed by the age of five.

Eating habits

A study of the stomach contents of narwhals showed that their diet is very limited and varies depending on the season. The first thing to note about narwhals' diet is that they do not feed during the summer. Examination of the narwhal's stomach contents during three other seasons showed that the animal had recently ingested food, but no dietary fiber was found in the stomach during the summer months.

In winter, narwhals remain in shallow areas of bays, where they feed almost exclusively on bottom-dwelling fish. During the Arctic summer they move into open ocean waters, so their diet expands to include other fish species such as cod and halibut, as well as squid and shrimp. In spring, the narwhal feeds mainly on arctic cod and cod. Crustaceans were also found in their stomachs, but fish and cephalopods were much more common.

Because narwhals do not have well-developed teeth in their mouths, they are thought to suck in prey and swallow it whole.

Enemies

Narwhals are hunted by polar predators. They can be dealt with mercilessly:

• killer whales;
• White bears;
• polar sharks;
• walruses.

Hiding from predators, the narwhal has to dive to great depths and hide under the ice. Also, the enemy of animals is man. He exterminated them for decades.

Killer whale is the enemy of narwhals

How many narwhals are there today?

According to the IUCN Red List of Threatened Species, the global population of narwhals numbers approximately 123,000 adults. Narwhals are currently listed as "least concern". Although they are not currently in danger of extinction, without fisheries controls they could be at risk of extinction. The narwhal population is also declining as a result of shipping. The route of ships often intersects the migration of these toothed whales, which leads to the death of some individuals.

Climate change is also a threat to narwhals. Like most Arctic predators, narwhals rely heavily on sea ice for their survival. They use it to hide from predators and catch prey. Rising sea temperatures have led to declines in narwhal populations in Southeast Greenland.

The European Union recently banned the sale of narwhal tusks in hopes of reducing the number of animals killed by humans for their tusks.

Population and conservation status

The number of narwhals, according to scientists, is approximately 50,000. It is difficult to give an exact figure, since they live in places that are difficult for people to reach.

So far there has been no decline in narwhal numbers on a global scale, but the species is approaching the “vulnerable” status and is classified as rare in the third category. The narwhal was included in the lists of the International Red Book.

The following reasons contribute to the extinction of the species:

• animal hunting;
• predators;
• pollution of ocean waters.

Due to the fact that the population of the species began to decline, narwhal fishing was limited: it is forbidden to catch cubs and females, only the indigenous peoples of the north are allowed to catch males.

Special production quotas have been introduced in Greenland and Canada. Interstate and regional agreements related to measures to preserve the ecological environment of the oceans have been adopted.

Habitat

Narwhals occupy one of the northernmost habitats of any cetacean species, between 70 and 80° north latitude. They are more demanding of their habitat than other whales and for this reason have a limited range. Narwhals are rarely found far from loose ice, and prefer deep waters. The largest concentrations of narwhals are concentrated in the Davis Strait, Baffin Sea and Greenland Sea. The advance and retreat of ice initiates migration.

In summer, narwhals occupy deep bays and fjords. The most famous and probably the world's largest population of narwhals lives in the deep bays of the eastern Canadian Arctic and northwestern Greenland.

Interesting Facts

1. Male narwhals weigh three times more than females.
2. If a narwhal's tusk breaks, it will not grow back.
3. Narwhals do not survive in captivity; they die very quickly. In the wild, narwhals live 50-56 years.
4. “Corpse (dead) whale” is how “narwhal” is translated from Icelandic.
5. If a narwhal gets angry, it can sink a boat. The highly durable tusk can penetrate the sides of a small boat.
6. When a narwhal needs to take in air, it can break the ice with either its tusk or its back. It easily breaks through a five-centimeter thick layer of ice.