Biology Of The Narwhal (Monodon Monocerus)
- Kingdom: Animalia
- Phylum: Chordata
- Class: Mammalia
- Order: Cetacea
- Suborder: Odontoceti
- Family: Monodontidae
- Genus: Monodon
- Species: Monodon monoceros
Narwhals have two teeth in their upper jaw. While both male and female narwhals can grow tusks, generally only male narwhals do so. The narwhal tusk grows from the left tooth of the narwhal.
In very rare cases, a second tusk will grow from the right tooth as well. These are called double narwhal tusks, or twin narwhal tusks. For more information about this fascinating phenomenon, see our Double Narwhal Tusk page.
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.
Narwhal tusks have been known to grow near 10 feet (3 metres) in length, and to weigh 22 pounds (10 kilograms). Such lengths and weights are, however, uncommon. The overall length of a narwhal tusk depends on the narwhal itself and the narwhal's age.
Male narwhals average 15.4 feet (4.7 metres) in length, not including their tusks, and weigh on average 3,484 pounds (1,580 kilograms). Females average 13.5 feet (4.1 metres) in length, and weigh on average 2,116 pounds (960 kilograms).
Male narwhals have been observed crossing their tusks with other male narwhals during the mating season, presumably fighting for dominance and for their right to mate with preferred female narwhals.
It is suspected that narwhal tusks are also used as sensory organs. They may process tactile information, allowing narwhals to identify and communicate with one another through tapping and scraping. Studies suggest that the nerve system found within narwhal tusks may detect temperature, pressure, motion, and chemical-solution gradients. Chemical cues may help narwhals detect prey and may also have a role, as do human pheromones, in intraspecies communication. The complexity of narwhal tusks offers a unique challenge to scientists, as the development of narwhal tusks defy the standard principles and properties of teeth.
Like all whales, narwhals are deep swimmers and divers. Narwhals have been observed diving nearly 900 metres deep several times a day.
During the summer, narwhals tend to travel in small groups of less than 10 individual narwhals. During the spring and fall migrations, however, narwhals may gather into groups consisting of hundreds of narwhals. Because individual narwhals move for long distances under water, it is difficult to obtain accurate estimates of the numbers of individuals in large groups.
Narwhals eat a varied diet consisting in part of fishes and invertebrates. Further study is required to accurately determine the physiological requirements of narwhals and their ability to adapt to environmental changes and shifts in the availability of prey species.