The spiral in the tusk of the narwhal has been fancifully, but never satisfactorily, explained. Spiral growths are common in the animal kingdom and share the feature of having straight axes. A curved tusk would hinder the narwhal swimming; a spiral mode of growth ensures overall straightness even if the tusk grows irregularly. The need to keep the tusk straight completely and satisfactorily explains the spiral.
No takes yet. Share an insight, caveat, or question.
Kingsley et al. (1988) studied this question.
Synapse has enriched 5 related papers. Consider them for comparative context: