Film title: The mystery of the narwhal tooth
You've probably seen some pretty strange teeth.
The massive jaws of a crocodile.
What about snake fangs?
Or walrus tusks?
But have you ever seen a tooth as odd as this?
This whale is called a narwhal, and that spike is actually a gigantic tooth.
narwhal
It is such an odd looking tooth that what the narwhals use it for has been a mystery for centuries.
Here's what we do know about the tooth.
It's an incisor tooth.
incisor tooth
It grows through the animal's jaw and twists through its lip.
The tooth, called a tusk, can grow up to 3 metres in length ... nearly half as long as the narwhal itself.
tusk
Imagine if you had a tooth that long!
The tusk is flexible and can bend without breaking.
Normally, female narwhals do not have a tusk.
Over the years, there have been many suggestions for its purpose: that it's used to break the ice in the Arctic waters, or that the males use it as a weapon to fight each other, or, just as male peacocks use their colourful feathers to attract a mate, so might male narwhals use this tooth to attract females.
But it was only when scientists looked at the tusk under a microscope a few years ago that they got their biggest clue.
They discovered that while other teeth are hard on the outside and soft on the sensitive inside, the narwhal's tusk is the other way round...
Hard inside and sensitive on the outside.
For that reason, many scientists now believe the narwhal's tusk is a sensory organ.
sensory organ
It can sense changes in the temperature and salt concentration of the sea, as well as the chemicals associated with the narwhal's food.
All this information helps the narwhal survive in its Arctic home.
So while the narwhal's tooth may look strange, it's shaped this way for very good reasons.
The narwhal's tooth is a sensory organ.
Learning points
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