Conventional mechanisms of evolution do not help explain these expressions of teeth.” The only tooth they have is the tusk. Its tusk, in fact, is a giant canine tooth—that can grow as long as 9 feet—with a distinct left-hand spiral, covered in a tissue called cementum, normally only found around the base of a tooth lodged in bone.Nweeia and a team of dentists and zoologists from the Smithsonian’s National Museum of Natural History, Harvard and other research organizations recently took a very close look at the dentition of the narwhal’s mouth. Also, the tusk has a straight axis and a spiraled morphology. Narwhals are mammals, which means they give birth, and have milk for their young. On top of all that, their tooth structure is all wonky. Narwhals …

5. With the amount of energy that it takes to produce that one tusk it could easily have 30 to 40 teeth in its mouth doing other things,” Nweeia explains. Incredibly, the narwhal’s only visible tooth is outside of its mouth. There are also a few "double tuskers": males that have two tusks rather than one, for unknown reasons. They exhibit uncharacteristic dimorphic or sexual expressions since females do not exhibit erupted tusks as commonly as males. Anyone who believes this needs to think through the practicalities, says Narwhal tusks can grow to lengths of 2-3m, and they eat relatively small prey like halibut, shrimp and squid. Tusks could be multifunctional: a good tusk could be a useful sensor, and as a result females might decide "that guy's got a great tusk, I'm going with him. These teeth are vestigial, meaning they have no function. The narwhal horn is actually the left canine tooth that protrudes from the head of a male. (Image courtesy Martin Nweeia) Recent research demonstrating a statistical link between the length of a male narwhal’s tusk and the size of its testes would seem to support this theory, except there is one hiccup: female narwhals can grow tusks too. The narwhals mouth is virtually toothless.

Unlike our own teeth, it is soft on the outside, and gradually gets hard and dense on the inside. 9.

“One might assume this animal once had more teeth positioned vertically in the mouth, but there is no evolutionary evidence to say that would be true,” Nweeia explains. This means they swim towards prey, and suck them with considerable force into their mouths. This is understandable, given that they belong to a group of animals known as ""A lot of people think this whale has teeth in its mouth, and it has none," says Nweeia.

Spearing these animals would be really difficult, and even if a narwhal managed it, it would not have any other appendages long enough to retrieve the fish from its tusk.Many people also have the idea that narwhals chew their food.

The horn can grow as long as nine feet. Narwhals have no actual teeth protruding inside their mouth, but that’s okay because they are suction feeders swallowing their prey whole.

"Cartoons sometimes suggest that narwhals are fierce creatures, perhaps dueling with their tusks.But that is not what Westdal has seen. "The tusk is most common in males and is only infrequently found in females," says Westdal. That is not particularly surprising, as humans have hunted them for centuries. Preferring not to wait, conservationists are already trying to protect critical areas like The pregnancy lasts for about 14 months, and calves are born in the spring. Its tusk, in fact, is a giant canine tooth—that can grow as long as 9 feet—with a distinct left-hand spiral, covered in a tissue called cementum, normally only found around the base of a tooth lodged in bone. Maybe it is an aggressive weapon for narwhal-narwhal battles, or for fending off predators. The reality is even stranger The narwhal's tusk was once passed off for exorbitant sums as unicorn horn But they spend long Arctic winters in dark, pack-ice covered waters, and live in vast remote seas that are difficult to get to. That suggests that it isn't "anything special required for survival", but is something to do with courtship and mating.They are not mutually exclusive explanations, says Nweeia. A male narwhal normally measures about 15 feet long at maturity.

Narwhal horns grow in clockwise helix spirals. In a new paper published in The Anatomical Record, the team determined:A second pair of tiny teeth is located in open tooth sockets in the narwhal’s snout alongside the tusks. When a dentist says “open wide,” he or she knows pretty much what they’ll find inside a patient’s mouth. The right canine stays embedded, and no other teeth protrude from the mouth. A normal tooth, or even tusk, is tough on the outside, and soft on the inside. "We don't know the answers to this at all," says Westdal.

It is a mainly male feature, but occasionally female narwhals have one. The narwhal tusk is "essentially built inside out," says Nweeia. (Photo by Joseph Meehan)“It is striking when you think that this animal decided to take all of its tooth-producing energy and put it into one thing [a tusk] that sticks out nine feet into the ocean. “The tusks are an extreme example of dental asymmetry. That's why we've put together these 8 reasons for why your mouth … Diet. Close inspection across many specimens reveal extreme variation in location, morphology and histology (tissue structure) of these teeth, all indications they “are following a pattern consistent with evolutionary obsolescence,” the scientists write.An array of vestigial teeth collected from narwhals.

From left, James Mead, curator emeritus, Museum of Natural History; Ted Cranford, San Diego State University; and Martin Nweeia. That is not seen in other mammalian teeth except when they are diseased. They studied more than 130 skulls in museum collections and 21 skulls of narwhals killed by native hunters in Canada. Narwhal fluke design helps compensate for drag caused by tuskNew fossil whale species raises mystery regarding why narwhals and belugas live only in cold water