Meet the Narwhal
Neptune's Note XV
Name: Known as the unicorns of the sea, the narwhal gets its fascinating name from its equally fascinating appearance. Narwhal comes from nárhval, an Old Norse word meaning ‘corpse-whale’ most likely referring to their grey, mottled skin. While their scientific name, Monodon monoceros points to their most distinctive feature, their tusk, and is derived from Greek to mean ‘single-tooth single-horn’.
Family: The closest living relative of the narwhal is the beluga and together they make up the two living representatives of the Monodontidae family. A phylogenetic study based on mitochondrial DNA of Monodontidae fossils revealed that they likely split from one another around 4.98 million years ago to form their separate species. There are thought to be four other extinct species in the family.
Genus: Narwhal are the only members of the genus Monodon.
Location: Like their close cousins, this species is native to the Arctic1, inhabiting waters around Canada, Greenland, and Russia. Every year they migrate to shallow, ice-free waters, with the same animals returning to their preferred sites in subsequent years.
Status: The Narwhal is listed with a ‘Least Concern’ status by the International Union for Conservation of Nature (IUCN).
Population: The narwhal population is thought to be somewhere between 80,000 and 170,000 individuals – high or low, it’s considered a healthy range.
Weight: A narwhal’s weight can be between 800 to 1,600 kg, males can be more than 75% heavier than females, which explains the range.
Length: A fully grown narwhal can grow up to 5.5 metres (18 feet) in length, but the average is somewhere between 3 and 5 metres with males being slightly longer.
Anatomy: There's no animal quite like the narwhal in appearance. These stocky cetaceans have a blunt snout, large melon, and a shallow ridge instead of a dorsal fin. Along with their jointed neck vertebrae, (unusual for whales, who typically have fused neck bones) which gives them a greater range of flexibility, they are perfectly adapted to navigating the sea ice in their Arctic environment.
But it’s their pronounced tusk that really sets them apart. It’s actually rather a tooth than a tusk and it can grow up to 3 metres long. While scientists have debated its purpose for years, we now know this tusk is essentially a giant sensory organ, packed with up to 10 million nerve endings that can detect changes in water temperature and salinity. Though typically only found on males, there have been sightings of females with a tusk and males without2, and unlike the rest of their anatomy, it seemingly isn't actually necessary for survival. It is generally thought the tusk indicates social status and a secondary function that is associated with sexual selection.
Their colouring changes dramatically throughout their lives – newborns start out blue-grey, before darkening to blue-black as juveniles. By adulthood they have developed a distinctive mottled pattern, with blackish-brown markings over white, and as they age, they become increasingly pale with senior narwhals being almost completely white.
Built for deep diving, narwhals have more myoglobin in their muscles than most marine mammals, enabling them to reach depths of nearly a mile. A thick layer of blubber, accounting for a third of their body mass, keeps them warm in frigid waters, while their slow-twitch muscles allow for precise movements. Even their tail flukes are specially adapted – males have inward-bent flukes while females have a sweep-back on the front margins, an evolutionary design that reduces drag from the males' tusks.
Diet: Narwhals actually lack well-developed teeth for chewing. Instead, they catch prey by swimming close to them and sucking them in whole. Their menu mainly consists of Greenland halibut, Arctic and polar cod, with armhook squid and shrimp making up the rest. They are also partial to wolffish, capelin, and skate eggs. Most meals are taken at the ice floe edge or in ice-free summer waters.
Reproduction: Narwhals can breed with their close cousins, the beluga whale, but generally mate with their own kind among offshore pack ice. After a 15-month pregnancy, females give birth to a single calf in late summer. Newborns are a tiny 1.5 metres (less than 5 feet!) and are white or light grey, gradually building up their protective blubber layer as they nurse.
Amazingly, narwhals are one of the few animals that experience menopause, living for decades after they have finished breeding. Recent research suggests this is to help with calf survival, as menopausal females continue protecting young in the pod. This is the case for five species of toothed whale who all achieve higher overall longevity than other species whilst their reproductive period remains the same. Scientists have hypothesised that this is because toothed whale calves are more difficult for a single female to rear and so the help of the pod is needed. Females can live for an impressive 115 years, while males typically reach 84 – though the average lifespan is around 50 years.
Social habits: Like many whales, narwhals are highly social creatures. They typically travel in small pods of three to eight individuals, though these groups can grow to around twenty. Some pods include 'nurseries' with females and their young, others are just bachelor groups of juvenile or adult males, but mixed groups do sometimes occur too. In some summer months these pods come together in impressive gatherings of 500 to over 1,000 individuals.
Communication between pod members happens through a variety of clicks, whistles and knocks, created by air moving through chambers near their blowhole. Calls recorded from the same pod are more similar than those from different pods, suggesting they might have group-specific 'dialects'.
During winter, they make some of the deepest dives recorded for any cetacean, diving at least 800 metres more than 15 times each day. These dives can last up to 25 minutes, with their specialised melon helping them navigate and hunt using echolocation in the dark depths.
Unique facts:
The greatest dive depth recorded is 1,500 m (4,921 feet).
A group of Narwhals is called a blessing.
Their tusks are hollow.
Threats they face:
As one of the Arctic species most vulnerable to climate change, narwhals are severely impacted by sea ice decline, especially in their northern wintering grounds such as the Baffin Bay and Davis Strait regions which satellite data has shown has a significant reduction in sea ice. Despite changing conditions, they return to the same foraging areas they learned early in life, making it harder to adapt as these areas transform.
Narwhals can suffocate when they fail to migrate before the Arctic freezes over in late autumn as they need breathing holes at least 0.5 metres wide and no more than 1,450 metres apart. When these conditions aren't met, they can drown or starve as the ice thickens.
About 1,000 narwhals are hunted annually for their skin, meat, teeth, tusks and vertebrae, and they have been for thousands of years by Inuit in northern Canada and Greenland. Hunters will often take advantage of instances when narwhals are trapped in pack ice.
Increased oil and gas exploration in the Arctic means more shipping vessels, raising the risk of collisions. The resulting underwater noise pollution also interferes with their communication and navigation.
Both polar bears and orcas hunt narwhals. Polar bears have been spotted waiting at breathing holes to catch young whales, while orcas have been known to attack and kill entire pods. Rather than trying to outswim these predators, narwhals often hide under ice floes.
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Amie 🐋
The only other native species is the bowhead whale.
It's rare but some narwhals grow two tusks!
Such wonderful animals - thanks so much for sharing :-)
Great learning for me with this post and, like another reader, it was a "blessing" to now know so much more than I did about these marvelous creatures.