---
title: "Scientists Decode the Narwhal Tusk's Spiral: How Opposing Coils Keep the Tooth Straight"
description: "Using synchrotron 3D tomography, scientists described the structure of the narwhal tusk: counter-directed spirals of dentin and cementum keep the tooth straight. The tusk's function — sensory or demonstrative — remains a subject of debate."
date: 2026-08-19T23:03:07.000Z
lang: en
url: https://xab.info/en/posts/narwhal-tusk-spiral-decoded-opposing-coils-keep-tooth-straight
tags: [narval, tusk, synchrotron, dentin, marine-biology, research]
publisher: "XAB.info"
---

# Scientists Decode the Narwhal Tusk's Spiral: How Opposing Coils Keep the Tooth Straight

![Narwhals with long spiral tusks swimming in turquoise water, aerial view; the spiral tooth structure studied by scientists](https://xab.info/media/2026/08/20/razgadka-struktury-roga-narvala/razgadka-struktury-roga-narvala-1.webp)

## 🎯 Key Points

- The inner dentin of the narwhal tusk coils clockwise, while the outer cementum coils in the opposite direction, which keeps the tooth in a straight form.
- The study was conducted using 3D X-ray analysis at three European synchrotron accelerator centres.
- Annual rings resembling tree rings were found in the tusks, which may reflect the development and life of an animal living up to 80 years.
- The tusk's function remains disputed: some scientists consider it sensory, while others link it to dominance display in males.

An international team of researchers has, for the first time, fully described the internal structure of the narwhal tusk — the only tooth in nature that simultaneously possesses a spiral and a straight form and can reach three metres in length. The work was the result of applying advanced 3D X-ray imaging technology at three synchrotron particle accelerator centres in Europe, which allowed a look inside a structure inaccessible to conventional imaging methods. In male narwhals, the left canine grows through the jaw and upper lip, forming a single outward-projecting tusk, while the right canine remains hidden inside the skull.

### Synchrotron tomography as the key to microstructure

The use of synchrotron radiation at three European centres gave scientists the ability to obtain detailed three-dimensional images of the tusk's internal layers. It was this approach that made it possible to separate and trace individual tissues — dentin and cementum — and to establish their spatial orientation. The study's lead author, chemist Henrik Birckedal from Aarhus University (Denmark), emphasises that without such high resolution the spiral geometry would have remained hidden behind the tooth's outer surface.

### Two opposing spirals keep the tusk straight

The key finding is that the inner dentin coils in a clockwise spiral, while the outer cementum coils in the opposite direction. These two counter-directed spiral structures create compensating forces that prevent the tusk from curving like elephant tusks and preserve its characteristic straight form. Birckedal compares this construction to a screw that continuously projects outward rather than penetrating deeply into an object, which explains the mechanical stability of such a long and thin tooth.

### Annual rings and the origin of the samples

In addition to geometry, the scientists found annual rings in the tusks, reminiscent of tree rings, which potentially may carry information about the development and life of an animal capable of living to 80 years. For the analysis, the team used museum specimens, as well as samples collected by the Inuit indigenous people in Greenland during traditional narwhal hunting for sustenance, which ensured the representativeness of the sample.

### Contradictory data

The tusk's structure has been decoded, yet its true purpose remains a subject of scientific debate. Early theories suggested that narwhals use the tusk to hunt prey or to determine water temperature and salinity. The research group considers these hypotheses less convincing, since tusks develop almost exclusively in males; at the same time, cases have previously been observed in which two males apparently displayed their tusks before a female, giving rise to the version of the tusk's role in dominance display and attracting a mate. Meanwhile, the leading expert on narwhal tusks, anthropologist-dentist Martin Nweya from Harvard University, relying on his earlier research, insists that the tusk's main function is a sensory system. Thus, the two main viewpoints — demonstrative and sensory — still coexist in scientific discourse.

### Significance of the work for biology and morphology

Despite the ongoing disagreements over the practical use of the tusk, Nweya regards the new study as a significant contribution to refining the microstructure and unique morphology of the narwhal tooth. The data obtained on the counter-directed spirals of dentin and cementum open new possibilities for studying the growth, age and, possibly, physiological functions of this rare marine mammal, and also serve as an example of how synchrotron methods change our understanding of animal anatomy.

## 🔍 Fact-Check Verification

- [Decoding the mysteries of the narwhal's spiral tusk.](https://www.vietnam.vn/ru/giai-ma-bi-mat-ve-chiec-sung-xoan-cua-ky-lan-bien) - Источник подтверждает метод синхротронной 3D-томографии в трёх европейских центрах, встречные спирали дентина и цемента, годичные кольца, происхождение образцов (музеи и инуиты Гренландии) и спор о функции рога между сенсорной гипотезой Нвеи и демонстративной версией авторов.

## ❓ FAQ

### Q: Why doesn't the narwhal tusk curve like elephant tusks?
**A:** Because the inner dentin coils in a clockwise spiral, while the outer cementum coils in the opposite direction. These counter-directed structures create compensating forces that preserve the tooth's straight form.

### Q: What method was used to study the narwhal tusk?
**A:** Using advanced 3D X-ray imaging technology at three synchrotron particle accelerator centres in Europe.

### Q: What else did the scientists find in the tusks?
**A:** Annual rings resembling tree rings, which may carry information about the development and life of an animal living up to 80 years.

### Q: What is the function of the narwhal tusk?
**A:** It remains disputed: the study's authors lean toward dominance display in males, while Harvard anthropologist-dentist Martin Nweya considers the main function to be a sensory system.