{"id":2207301,"date":"2026-09-13T06:00:32","date_gmt":"2026-09-13T05:00:32","guid":{"rendered":"https:\/\/focusingonwildlife.com\/news\/?p=2207301"},"modified":"2026-09-12T14:04:16","modified_gmt":"2026-09-12T13:04:16","slug":"that-puzzled-us-quite-a-bit-scientists-found-another-astonishing-thing-about-narwhals-after-x-raying-their-tusks","status":"publish","type":"post","link":"https:\/\/focusingonwildlife.com\/news\/that-puzzled-us-quite-a-bit-scientists-found-another-astonishing-thing-about-narwhals-after-x-raying-their-tusks\/","title":{"rendered":"\u201cThat puzzled us quite a bit.\u201d Scientists found another astonishing thing about narwhals after X-raying their tusks"},"content":{"rendered":"

An international team of researchers has solved the mystery of how\u00a0narwhal\u00a0tusks acquire their twisted structure. The findings have been\u00a0published\u00a0in the journal\u00a0Nature Communications.\u00a0<\/em><\/p>\n

Narwhals are often called the \u2018unicorns of the seas\u2019, and not without reason. Back in the Middle Ages and the Renaissance, the narwhal tusk was often sold as a unicorn horn. The mythical unicorn was so revered that the Danish-Norwegian king Frederik III famously ordered a coronation chair made entirely from narwhal tusks as a sign of his power and social status.<\/p>\n

Despite extensive research, we still don\u2019t know what exactly the\u00a0narwhal uses its tusk for. Scientists have many theories \u2013 sexual signalling, hunting, infighting or play.<\/p>\n

But for now, scientists solved another mystery \u2013 how exactly does the tusk obtain its characteristic twisted structure?<\/p>\n

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\"A
A close up of a narwhal’s head showing the tusk protruding from the upper jaw. Credit: Mads Peter Heide-J\u00f8rgensen<\/figcaption><\/figure>
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The structure<\/strong><\/h3>\n

Narwhals aren\u2019t the only animals that sport this long, pointed tooth, but it\u2019s still unique \u2013\u00a0\u00a0it\u2019s the only one that sticks straight out in a spiralled form and doesn\u2019t follow a curved shape.<\/p>\n

Narwhals have two upper teeth \u2013 the left canine tooth in males grows into the twisted husk, protruding from the maxillary bone and through the upper left lip. The right tooth in males and both teeth in females are embedded in the skull.<\/p>\n

There are rare cases of females growing a tusk and males without one \u2013\u00a0and even double-tusked individuals have been observed. The tusk can exceed a whopping 2m in length and always twists in a left-handed helix. Even in the rare cases when it\u2019s the right tooth, it develops into a tusk.<\/p>\n

\u201cLike bones or other teeth in the animal kingdom, the narwhal tusk is a complex composite material whose structure extends from tiny nanoscale building blocks to the visible form of the entire tooth,\u201d says Marianne Liebi, co-author of the study.<\/p>\n

The tusk is made of dentine: the same material that forms the core of human teeth. On the outside, it\u2019s covered by a thinner layer of cementum, a tissue that in other mammals normally occurs only at the root of the tooth. Both parts contain collagen fibres, acting as internal reinforcement, which are in turn strengthened by tiny mineral crystals that give the material its hardness.<\/p>\n

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Narwhals at the surface displaying their tusks. Credit: Mads Peter Heide-J\u00f8rgensen<\/figcaption><\/figure>
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The challenge<\/strong><\/h3>\n

It\u2019s exactly this complicated architecture of the tusk that presented the main challenge for the researchers.<\/p>\n

\u201cThe collagen fibres and mineral crystals are on the nanometre scale, while the spiral of the tooth only becomes visible at centimetre and metre lengths,\u201d explains Liebi.<\/p>\n

Visualising the shape of the tusk in both ranges required a specific X-ray technique: tensor tomography. In this method, the tooth is rotated and scanned point by point, and when the X-rays come across regularly arranged structures within the material, they produce patterns. From those patterns, scientists can calculate how the nanometre-sized collagen fibres are oriented inside.<\/p>\n

Finally, from millions of measurements, a 3D image of the internal architecture of the tusk can be constructed \u2013 from the tiny, nanometre-scale fibres to the macroscopic form of the whole tooth.<\/p>\n

But, to the surprise of the research team, the data revealed nothing.<\/p>\n

\u201cThat puzzled us quite a bit,\u201d says Liebi. Based on previous mechanical tests, the scientists thought the spiral shape would be reflected in the collagen fibres and mineral crystals. \u201cBut instead of a helix, all we saw was a regular pattern.\u201d<\/p>\n

The answer to this puzzle required them to take a step back. Instead of focusing on individual pixels, they needed to analyse spatial orientation.<\/p>\n

\u201cWhen we compared how these points were oriented relative to each other, a directional trend began to appear,\u201d recalls the first author of the study, Adrian Rodriguez-Palomo.<\/p>\n

\u201cAll we had to do then was connect the dots \u2013 as in a children\u2019s paint-by-numbers kit \u2013 and suddenly the structure became visible: two intertwined spirals.\u201d<\/p>\n

The outer layer of the tooth forms a left-handed helix, while the mineralised collagen structures inside the tooth follow a spiral pattern in the opposite direction.<\/p>\n

Reinforcement<\/strong><\/h3>\n

This newly-discovered structure is no accident \u2013 the double helix configuration makes the tooth more stable under bending and torsion. This is echoed across the animal kingdom, for example, in the helical reinforcement of the deep-sea glass sponge\u00a0Euplectella aspergillum<\/em>, which helps it withstand strong ocean currents.<\/p>\n

The study also determined that the double-spiral structure is encoded in the animal\u2019s genetics and remains stable throughout its life. The maximum lifespan for a narwhal is around 80 years, and the tooth continues to grow with the animal.<\/p>\n

This discovery provides new insight into how complicated structures form in the natural world, which can be used to inspire the design of materials in fields such as construction or medicine. It also could offer a glance into environmental and climate conditions of the past.<\/p>\n

\u201cSince whales can live up to 80 years, their teeth form a kind of historical record of changing environmental conditions throughout the animal\u2019s lifetime,\u201d says Henrik Birkedal, who led the research project, from Denmark\u2019s Aarhus University.<\/p>\n

\u201cAnd because the North Atlantic is currently undergoing very rapid changes, it is obvious to investigate whether we can trace these changes in the hard tissue of the narwhal tusk. That is what we are now working on.\u201d<\/p>\n

This article<\/a> by Magda Patynska was first published by Discover Wildlife on 30 August 2026. Lead Image: Narwhals with tusks swimming in North West Greenland. Credit: Carsten Egevang.
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