Archive · 21 Aug 2026
Narwhal Tusk’s Opposing Spirals Reveal Secrets of Stability
A narwhal has a long tooth called a tusk that sticks out from its mouth.
Some tusks can grow as long as 10 feet.
Scientists used special three-dimensional X-ray pictures to look inside them.
They found that the outside twists in one direction, while the inside twists in the opposite direction.
This double spiral may help the tusk stay straight and strong.
It may also protect the tusk from bending or twisting too much.
Most male narwhals have one tusk, while only a few females do.
Scientists think tusks may help males compete, but their full purpose is still unknown.
Long ago, people mistakenly believed narwhal tusks were magical unicorn horns.
Three-dimensional X-ray imaging revealed opposite spiral patterns inside and outside narwhal tusks.
The outer cementum forms a left-handed spiral, while inner dentine forms a right-handed spiral.
Researchers say the double spiral may help tusks grow straight and resist bending and twisting.
Narwhal tusks can reach 10 feet (3 meters) and are found mostly in males.
The findings could inspire new bioinspired materials with improved mechanical stability.
- Who
- Researchers including materials chemist Henrik Birkedal of Aarhus University studied narwhal tusks.
- What
- The study decoded the tusk’s internal double-spiral structure using three-dimensional X-ray imaging.
- When
- The study was published on August 21, 2026.
- Where
- Narwhals live mainly in Arctic Ocean waters near Canada, Greenland, Norway and Russia; the research involved Aarhus University in Denmark.
- Why
- Researchers propose that the opposing spirals help tusks grow straight and remain stable against bending and twisting.
- Tusk type
- A narwhal tusk is a straight, elongated canine tooth.
- Maximum length
- Up to 10 feet (3 meters).
- Outer structure
- Cementum forms a left-handed spiral.
- Inner structure
- Dentine forms a right-handed spiral.
- Spiral materials
- Mineralized collagen fibrils create the tusk’s helical structure.
- Occurrence
- The vast majority of males and a small percentage of females have one tusk; some males have two.
- Possible functions
- Tusks may help establish social hierarchy and may also be used in play or as sensory organs.