Can someone here explain to me how narwhal tusks spin in the same direction? All other animal tusks point/spin in different directions from one another.
Not exactly an expert on this, but here's some possible reasons:
>little to no selection for different spins
>little evolutionary time to allow for mutation in the tusk-spinning gene
From those assumptions, I would conclude that whatever gene or genes that are responsible for the spiraling are very similar in every narwhal
Following up with some after thought.
The direction of the spiral may be related to the organization of cells in the area during development.
However the point still remains that there's little variation in this between narwhals
Though rare, there have been a few double-large-tusk narwhals, and they have the same spiraling so in any case the traits don't seem to be interdependent.
It's because the narwhal is asymmetrical. The "horn" (tooth) is always elongated on one side. The tusk spins outward because of the properties of the root cells. Now, why is the tusk always on one side? I have no clue.
Aside from very rare random mutations, it is always the canine on the left side of the upper jaw. Some have a double tusk defect, but it's rare.
I don't see why this is a big shock to people. What side is your heart on? Which one of your lungs is bigger? Does your large intestine curve left or right? Are any of your organs located symmetrically in your body? Do any of you have perfect facial symmetry? How about your teeth, how many people had braces as a kid?