The narwhale is a species of whale belonging to the Monodontidae family. Considered to be a white whale, the species has the distinctive feature of a helical tusk which may grow in size from 1,5 to 3 or more meters. These whales can be found in Artic waters for most of the year, with migratory patterns to warmer waters for breeding.
The narwhale, alongside the beluga whale, are white whales, and the only two extant species of the Monodontidate family, translated into one single tooth. This family belongs to the superfamily Delphinoidea or ocean dolphins within the parvorder Odontoceti, or toothed whales, alongside dolphins and purpoises.
These whales exhibit strong sexual dimorphism. Males are typically larger than females, reaching 5.5 meters in length but with an average of 4 meters. Females average 3.5 meters in length. Invidviduals may weight anywhere from 800 to 1,600 kg.
The distinctive characteristic of these whales is the large tusk that may extend from 1.5 to 3.1 meters in length. It is not a real tusk, but actually a canine, the only one these whales have, protruding from the upper left jaw and forming a helical left turn tusk. These tusks are innerved and they are thought to be used to test the quality of water. They are also occasionally used by males when fighting, a process called tusking. Some males may develop two tusks with a chance of 1 in 500 cases, and females may also develop one, with a 15 percent chance. However, female tusks are considerably shorter than those of males.
Narwhale populations inhabit the Arctic seas all year round. They are found predominantly in Russian waters and the Atlantic. Populations can be found from the Hudson Bay to the East Coast of Greenland to Svalbald. It has been proven that these whales can survive at depths of 1,500 meters in dives lasting from a few minutes to as much as 25 minutes. This comprises the descent, the time spent on the seabed as well as the ascent, as the depths involved require a slower transit due to the increased pressure at lower depths. Compared to many other whales, the species has a relatively specialized diet. The diet is composed mainly of Arctic cod and Greenland halibut, with sometimes cuttlefish, small squid and shrimp. However, this diet is mainly characteristic to the warmer season, while in winter these whales may rely more on benthic prey such as flatfish.
These whales usually live in groups or pods of 10 to 20 members. However, groups with as many as 500 may be observed in large aggregations which occur during the breeding season. Before mating, males may rub their tusks in an action called tusking to display dominance hierarchy and have increased chances of mating. Adults usually mate from April to May. Gestation usually lasts for about 14 months. The calves measure 1.6 meters on average, will suckle for 20 months and will spend a long time with the pod to learn survival skills. Narwhale females will reach sexual maturity in 5 to 8 years while males in 11 to 13 years.