Auger-Methe, et al. The mating systems of narwhals are not known. Reeves and Tracey, It is assumed that narwhals reach sexual maturity at the same rate as their close relatives the beluga whale, Delphinapterus leucas. This would mean males reach maturity at eight to nine years for males and four to seven years for females.
Narwhals are seasonal breeders and thought to mate between March and May while in their summer home. Following a fourteen month gestation they give birth the next June. The newborns are assumed to stay with their mother for at least the next twenty months of lactation, however, there are conflicting opinions on the exact duration of lactation.
As a result of a long lactation period, female narwhals conceive every two to three years. Narwhals generally give birth to a single eighty kilogram offspring, although twins have been seen occasionally. Narwhal calves are born tail first and begin swimming shortly after birth.
It is assumed that the protruding tooth in males is used by the females to judge the fitness of males, and thereby choose a mate. However, there are still conflicting opinions about the purpose of the tooth. Klinowska, ; Marcoux, et al. Gestation is thought to last about fourteen months in the narwhal, followed by twenty months of lactation.
Males are thought to have some parental investment, because males and females generally do not travel together, unless there is a calf with them. This is based on observations of traveling narwhals, however, whether the males provide food or protection for the offspring is not known.
Family association after weaning is also not known. Current studies are examining the relatedness of narwhals that live together, but no conclusions have been made yet. In the past the narwhals lifespan has been estimated by counting the growth rings on its unerupted tooth. However, after being reviewed by Hay this method does not seem accurate.
If true, it would make their reproductive capabilities in a lifetime to equal twice that of the beluga whale, Delphinapterus leucas the only other extant species in the family Monodontidae.
It is generally accepted that narwhals live for about fifty years in the wild. Without an appropriate method of estimating age, this cannot be confirmed. The longest a narwhal has lived in captivity is four months, and the shortest is one month.
Therefore, attempts at captivity have not been successful. Hayssen, ; Klinowska, Narwhals are a highly social species, and are usually found in pods ranging from two to twenty-five members, with an average of 3.
These pods become much larger while migrating as many pods merge into one large herd. In this case groups of several hundred members are possible.
After migration, however, the whales return to their original smaller pods. Pods do not seem to follow a pattern of sex, age, or relatedness. Although it is widely accepted that the narwhal is a social species, details of their social structure are not known. Occasionally narwhal can get caught in savassat, or open areas surrounded by too much ice to allow the narwhal to escape. This usually results in the death of all the trapped animals either by predation or starvation.
The whales have been seen using their heads to smash into the ice in an effort to break it. Unfortunately, this causes water to splash out of the hole, which freezes and reinforces their entrapment. There have also been observations of narwhals being extremely careful not to harm other members of its group with their tooth while stuck in a savassat.
Narwhals tend to be very inactive while they are at the surface. They have also been known to slowly sink when they sense vibrations from a ship. This paired with their coloration makes it hard to observe them. Klinowska, ; Lydersen, et al.
The narwhal communicates acoustically. This species has two different types of calls that it is able to produce. The first is categorized as a pulse; this type of call is typically between 12 and 20kHz. As the name suggests, this is a short burst of sound, or click, that is sent out frequently.
These calls are likely used as a type of echolocation for the whale, allowing it to efficiently locate and catch prey. This type of call is also used for spatial orientation and likely helps the whales stay together while they are migrating. The other type of acoustic call is the whistle.
Unlike the pulsed call, whistles are longer calls with varying frequency and are likely used mainly for communication. These calls vary from Hz to 10kHz.
Recent research has suggested that whistles can also be group specific, meaning that the calls of narwhals in one group are more similar to each other than they are to the calls of members of other groups. However, because of the challenges of understanding communication underwater in the wild, more specifics are not known about the possibility of a meaning behind narwhal whistles.
An examination of the tusk revealed about ten million nerve endings. This leads researchers to believe that the tusks have some sort of sensory function, but the specific function is not yet known. Bobechko and Stockton, ; Marcoux, ; Marcoux, et al. Studying the stomach contents of narwhal have shown that they have a very limited diet, and that it varies depending on the season. The first thing to note about narwhal diet is that they do not appear to feed during the summer.
Examining the contents of the narwhal stomach during the other three seasons revealed the food the narwhal had recently ingested, however, during the summer months, no tissues were found in the stomach. Diet during the fall and winter consists of Greenland halibut, Reinhardtius hippoglossoides , and boreoatlantic armhook squid, Gonatus fabricii.
During the spring narwhal eats polar cod, Boreogadus saida and Arctic cod, Arctogadus glacialis. These seasonal variations likely stem from the migration pattern of the narwhal. Crustaceans have also been found in narwhal stomachs, but fish and cephalopods are much more prevalent.
As a toothless whale, it is assumed that narwhals use suction to eat their prey. However, being an Arctic species that does not survive in captivity, this has not been tested. There has also been speculation that the narwhal tusk is used for spearing prey, or that it can be used as an instrument to disturb the sediment at the bottom of the ocean and reveal prey.
The likelihood of these two options is slim because tusks are most frequently found on males. If the tusk were an adaptation for food it would be found on all narwhal. Laidre, et al. Narwhals generally travel in small groups, and when being chased by a predator they have been seen getting closer together and traveling in a tighter group. This behavior has been seen in response to being chased by an orca, Orcinas orca , and when being chased by humans, Homo sapiens.
One defense mechanism of the narwhal is their coloration, which acts as a type of camouflage in the ocean. Lighter coloration on the bottom helps them blend in with the sky when looking up from under them, and the darker, mottled color on their dorsal side blends in with the deep ocean below when looking down at them.
The males are prized for their tusks, so when hunting occurs by humans, Homo sapiens , it is generally the adult males that are caught. This is thought to explain why adult males tend to stay farther offshore and spend less time at the surface than juveniles and females. This could be a possible adaptation to predation by humans, Homo sapiens. Narwhals have been found in the stomachs of Greenland sharks, Somniosus microcephalus , so it is assumed that narwhals are a part of their diet.
Narwhals have also been eaten by walrus, Odobensus rosmarus , and polar bears, Ursus maritimus , however, predation by these two species only occurs when the narwhals are trapped in a savassat and have no way of escaping to open water. Although there are hypothesis that the tooth is used as a weapon to prevent predation, there is no evidence to support that theory. If hybrids are infertile, as they often are, they would act as genetic dead ends for already small populations.
If they are fertile, the mixed genomes of their offspring could displace those of their respective parents. As the Arctic warms and its ice disappears, some scientists are concerned that once-isolated species could be meeting and mating more frequently, and damaging their own prospects in the process. Modern humans still carry the genes of Neanderthals, Denisovans, and our other ancient relatives, but those groups are all extinct now. If polar bears and narwhals get edged out in a world of pizzlies and narlugas, they could suffer the same fate.
Skip to content Site Navigation The Atlantic. Popular Latest. The Atlantic Crossword. Sign In Subscribe. Skulls of a a narwhal, b the narluga, and c a beluga Eline Lorenzen. A set of narluga teeth Eline Lorenzen. They have very little blubber at birth but put on weight rapidly during the 20 months or so in which they nurse upon the fatty milk of their mothers. Calves stay close to their mothers for protection and assistance during the nearly two years the calves needs to become self-sufficient.
By using the site, you agree to the uses of cookies and other technology as outlined in our Policy, and to our Terms of Use. Mating Mystery Though much of the reproductive and mating habits of narwhals remain a mystery -- chiefly because narwhals mate in pack ice offshore, where it is difficult to observe them -- some things are known.
Tusk Tasks The long tusk of the narwhal is actually one of two teeth this species of toothed whales, suborder Odontoceti, family Monodontidae possesses. Tusk Use During Mating Whether or not narwhals use their tusks for display or dueling during mating season is a subject of much speculation.
Mother and Baby Dark gray calves are born tail-first in June or July and average around 5 feet long. Elephant Life Cycles.
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