The Narwhal

Basic Description
 The narwhal is a toothed whale (cetacea, odontoceti)  of the monodontidae family. (Which consists of only beluga whales and narwhals as they both have a melon-like forehead, small or non-existent snout, and no true dorsal fin.) Having only two teeth, the well-known tusk that mostly male narwhals feature is actually the tooth on the upper left side of the jaw, which grows through the lip into a hollow, helical structure, and usually ranges from two to three meters in length. Although the main purpose is not completely clear, most scientists believe that this tusk is used by males to maintain social dominance hierarchies or to impress potential mates through the process of "tusking." (See physical adaptations) When born, young narwhals are a brown colour, but slowly become a bluish-grey mottled with white as they reach maturity. Average male narwhals are about five metres long, excluding the length of a tusk, and weigh around 1.8 tons; females are slightly smaller at an average length of four meters, and usually weigh about 1 ton.
 The narwhal is a migratory species that travels from winter habitat amongst dense Arctic pack ice in which narwhals breathe through breaks, leads, and small holes in the ice, to bays and other places nearer to the coast as the winter freeze ends and such leads open up into channels. Much like the beluga, narwhals use a wide variety of sounds regularly in order to communicate, also relying somewhat on their voices to navigate the icy Arctic waters by means of echolocation. Relying on various other aquatic animals within the ecosystem for food, the narwhal is carnivorous and has a basic diet of fish, some shellfish, and squid.

Niche 
 Most known narwhal populations reside in the Russian and Atlantic areas of the northern part of the globe and have a migratory lifestyle, moving  in pods of 10-100 to the coastline during the summer months and travelling further away from the coast in pods of five to ten to areas amongst dense pack ice in the winter. Narwhals living in the Arctic area between Canada and Greenland generally rely upon populations Polar and Arctic cod, Greenland halibut (a flatfish), shrimp, and Gonatus squid for sustenance, being known mainly to consume species living near the ocean floor, or benthic zone; however some have been observed  while feeding upon various other species of fish, shrimp and squid living within their ecosystem at shallower depths. Orcas and Greenland sharks have been known to prey upon narwhals in open waters, and this unique species is hunted by the Inuit people for their tusks and skin- which is rich in Vitamin C and necessary for a balanced Arctic diet. Walruses and polar bears have also been known to prey upon narwhals, but this seems to be an extremely rare occurrence, as is most predation of narwhals. Despite forays into the benthic zone for food, most narwhals are known to remain mostly in the sunlit upper zone and the middle zone, with occasional travels into the topmost part of the lower zone.
Physical Adaptations
 One of the most well-known features of the narwhal is a helical tusk extending from the left part of the upper jaw. This interesting characteristic mainly appears in male narwhals (although some spottings of tusked females have been noted), and although its purpose is not fully clear it is thought to help males maintain social dominance hierarchies. This activity, known as "tusking," occurs when male narwhals rub tusks with one another. This fascinating feature is also thought to be used as some sort of a hydronamic sensor, as millions of tiny nerves extend from a central nerve within the hollow tusk and travel quite near to the outer surface of the horn, which would make it sensitive to changes in water temperature.
 A basic physical adaptation of the narwhal would be its tail and fins, used in swimming motions to assist the narwhal in making its way through Arctic seas.
 Narwhals are also known for the physical adaptations that give them their extensive diving ability, making it easier for this species to find food when lesser amounts are available with forays into deeper waters, especially in the winter. (In winter, Narwhals have been known to dive regularly to a depth of 800 meters, with many dives reaching 1500 meters.) On average, narwhals may spend 25 minutes underwater without coming up for air - this most definitely testifies to the fascinating diving ability of many marine mammals, using lobed lungs that allow for more air retention, lower heart rates (bradycardia), and other adaptations such as the ability to store excess oxygen in the blood and the cartilagenous trachea that allows them to conserve oxygen. This ability to store oxygen in the blood also prevents such animals from suffering from decompression sickness as nitrogen cannot bubble into the bloodstream when there is so much oxygen already within, despite extremely high pressure.

 The other main physical adaptation of the narwhal species that makes it easier for these individuals to survive in frigid waters is having a cylindrical body shape covered in a thick layer of blubber, lacking dorsal fins with a small, round head and minute mouth. In such cold temperatures, this assists narwhals in retaining body heat.
 Narwhal skin is known to be countershaded, with darker colouring on top and lighter hues upon the underbelly, bottom of the tail, et cetera. This adaptation allows the narwhal to blend in with deeper water when seen from above, and to appear similar in colour to shallower, light-filled waters when seen from below. This acts as a form of camouflage and prevents predation to some extent.
Behavioural Adaptations
 A major behavioural adaption of those among the numbers of Monodon monoceros is the way in which they stay in fairly limited areas during the winter months, mainly making only small movements so as to conserve energy. The migration of narwhals from dense pack ice in summer so as to make their way to shallow coastal summering grounds is another behavioural adaptation of this intruiging creature; it may be considered that during the winter narwhals likely travel away from the coast to hunt fish such as the Greenland halibut and other benthic prey living in deeper waters when hunting in the upper or middle oceanic zone is not possible due to ice formation. The tendency of narwhal individuals to travel in pods ranging from five to ten in the winter months, when food is less available; rather than combining several groups as they do in the summer when resources are more accessible is another way in which these intelligent animals make it easier for themselves to survive.
 Enabled by a combination of both behavioural and physical adaptations in the narwhal, this creature is known to make some of the deepest dives recorded among marine mammals, especially in the winter when dependence upon benthic-zone food supplies increases. During this season, many narwhals are known to dive to at least 800 meters in depth quite regularly, with many dives going up to 1500 meters. One behavioural adaptation component of the narwhal's diving patterns and ability would be the adaptation made by narwhals that causes them to generally dive to a much lesser depth in summer because there is less need to go so deep in the search for sustenance, especially in shallower summering areas where many narwhals dive only from 30 to 300 meters on average.

Specialist, or Generalist?
 Although narwhals do migrate to assist themselves in surviving the different Arctic seasons, this creature is mainly a specialist in the general marine Arctic environment because narwhals are adapted specifically to live successfully in a frigid marine ecosystem with their compact body shape, thick layer of blubber, and the behaviours causing these animals to conserve energy by making only small-scale movements in the winter. Also, these creatures are adapted to compete for specific food sources widely available in their environment which could be considered fairly stable resources due to their general availability and the number of species that share them. Deep-diving and echolocation skills are two characteristics that make narwhals specifically adapted to hunt such creatures, also the way in which narwhals do follow some food resources further out to sea in winter (ex. Greenland halibut) indicates that they depend upon these creatures as a main food source and have therefore adapted in a manner that allows them to compete for these edible creatures.
Competition
 Within the species, male narwhals are known to compete for mates and for social dominance during the summer months through "tusking." Competition for food, especially among the average pods of five to ten during the winter when food is not as easily obtained may also affect those of the narwhal species when populations of prey are low or hard to find, or when many other species also compete for those of a specific group or species. Other species, such as the Sperm whale, Short-finned Pilot whale, Dall's porpoise, Baird's Beaked whale and many others are known to use the Gonatus squid as a food source, and the narwhal competes with beluga whales, ringed seals, and seabirds for polar cod; arctic cod is consumed also by most arctic marine mammals and seabirds. As few narwhal food resources are predated only by this animal, they must compete among various other aquatic species living in the Arctic for widely used food resources. One of the largest source of competition against the narwhal would be other whales in this ecosystem, competing for the usage of larger-sized species as food.
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Mating
 Narwhals tend to breed in the spring, with peak season usually occurring in mid-April. The most commonly known facet of narwhal mating rituals, "tusking" involves two males rubbing tusks together in a sort of motion similar to fencing, competing for the right to mate with a certain female. Male narwhals reach sexual maturity around the age of eight or nine, becoming a little more than four meters long on average (as they continue to grow) with tusk size generally increasing fairly rapidly around that time so as to allow for tusking competitions. Generally, tusks of a male narwhal become about 2 or 3 meters long at this point. Females reach maturity between the ages of four and seven. The gestation period of a narwhal is about 15 months, so that calves are usually mainly produced around July of the following year if concieved in April. This allows for newborns to adapt to Arctic life prior to the onset of  winter.
Narwhal Facts
·  The skin of adult narwhals is a mottled bluish-grey similar in colour to drowning victims and therefore the Old Norse word "nar," meaning corpse became the prefix of this creature's common name
·  On extremely rare occasions, male narwhals may have dual tusks, in which both teeth in the upper jaw have grown out. There has been only one recorded case of a female narwhal having two tusks, being that it is rare for females to grow tusks in the first place.
·  All attempt to keep narwhals in captivity have failed, with individuals usually dying within a few months after being taken from their natural habitat.
·  During the Medieval times, some Europeans were unaware of the existence of this creature and therefore considered narwhal horns sold by Vikings and others who made forays to the north to be those of mystical unicorns. These horns were sold for many times their weight in gold as during those times many believed that a cup made from the horn of a "unicorn" could negate the effects of any poison added to drinks, and that the horn itself could be used as a cure-all for poisoning and melancholia.
·  In the 1500s, it is known that Queen Elizabeth I received a carved and jewelled narwhal tusk for 10 000 pounds sterling - equivalent to about 1.5 or 2.5 million pounds today. At that time, 10 000 pounds was the cost of an average castle.
·  With age, narwhals are known to become much lighter in colouring as the size and number of their whitish patches increase. This may occur due to a loss of skin pigmentation.
·  Most narwhals are known to live for about 30 or 40 years
·  To find food, narwhals use echolocation. A series of high-pitched sounds are emitted by the narwhal through the nose, these sounds then travel through the water, bounce off objects, and return to the narwhal. By the time it takes for the sounds to return, a narwhal can predict how far away its prey is.