Top Stories· August 18, 2026 at 03:00 p.m.
New Study Unveils Double Helix Structure of Narwhal's Spiral Tusk
Key takeaways
- Narwhal tusks have a double helix structure
- The discovery was made using multiple imaging techniques
- The double-helix structure contributes to the tusk's stiffness and strength
A new study published in Nature Communications reveals that narwhal tusks, known for their distinctive spiral shape, have a double helix structure consisting of both left- and right-oriented spirals. This discovery sheds light on the unique properties of these tusks, which are composed of collagen fibrils and hydroxyapatite nanoparticles that orient themselves along the tusk's longitudinal axis.
The researchers used multiple imaging techniques to study two male narwhal tusk and skull specimens. The results showed a consistently high degree of anisotropy at all scales, with tiny systemic deviations creating the twisted structure. While the cementum layer forms the known left-handed helix, the dentine forms a right-handed helix.
The double-helix structure is believed to contribute to the tusk's remarkable stiffness and strength, allowing it to withstand strong forces without cracking. The team also noted a finer underlying microstructure in the cementum of collagen fiber bundles that they plan to study further.
Co-author Henrik Birkedal of Aarhus University in Denmark stated that whale teeth could serve as a historical record of changing environmental conditions throughout an animal's lifetime, and they are currently investigating whether these changes can be traced in the hard tissue of narwhal tusks.
