A peculiar feature in the natural world is the narwhal tusk, which can grow up to three meters long and is a straight upper tooth that protrudes through the whale’s lip on the left side. Researchers from different countries have uncovered the reason behind its straight growth, attributed to its distinct pattern of opposing spirals.
New findings published in the journal Nature Communications explain how the two opposing spirals, one turning right and the other left, contribute to the straight growth of the tusk. The investigation was initiated when a colleague studying organic chemistry raised questions about the handedness of molecules and the consistent leftward spiral pattern of narwhal tusks in Greenland.
Collaborating with biologists from Greenland and physicists from Sweden, the team delved into the molecular composition of the tusks and spirals to unravel the underlying structure. Through advanced imaging techniques akin to CT scans, they identified two opposing spirals: a left-handed spiral on the outer cementum layer and a right-handed spiral within the dentine layer.
This discovery not only explains the mystery of the narwhal’s straight tusk but also holds promise in illuminating the structural principles of human bones and similar biological phenomena, according to Henrik Birkedal from Aarhus University in Denmark.
Martin Nweeia, a narwhal biologist from Harvard University specializing in marine mammal teeth, lauded the research for delving into what he describes as the most extraordinary tooth globally and highlighting its sensory organ function. While teeth serve multiple purposes, Nweeia’s research indicates that the primary function of the narwhal tusk is sensory rather than defense or feeding.
Looking ahead, Nweeia emphasized the importance of further research, suggesting off-season studies and collaboration with Indigenous communities in the Canadian Arctic where most narwhals reside during the summer. He highlighted the significance of integrating scientific knowledge with traditional Inuit observations to gain a comprehensive understanding of these unique creatures.