Narwhal tusk helical structure decoded by international researchers

An international research team has decoded the biological mechanism behind the unique helical structure of the narwhal tusk. Using advanced 3D X-ray imaging and tensor tomography, scientists mapped the tusk’s architecture from the nanoscale to the centimeter scale.

The study, published in Nature Communications, reveals that the tusk’s characteristic spiral shape is driven by opposing microscopic structures. The outer layer of cementum forms a left-handed helix, while the inner dentin forms a right-handed helix. This arrangement of mineralized collagen fibrils creates a biological counterbalance, providing the tusk with both the hardness and flexibility required to withstand hydrodynamic forces during swimming.

While the exact evolutionary purpose of the tusk remains a subject of debate—with theories ranging from sensory perception of salinity and temperature to social hierarchy and mate selection—the research clarifies how this complex composite material is engineered by nature to remain both strong and resilient.