That, Neatoramanauts, is narwhal's mouth. Notice anything missing? That's right, narwhals have no teeth inside their mouth, and this presents an evolutionary conundrum:
“Nothing makes sense,” explains Martin Nweeia, a practicing New England dentist and member of the Smithsonian’s Department of Vertebrate Zoology and the Harvard School of Dental Medicine. For one, narwhals have no teeth. “They eat large fish, yet swallow them whole. If you look in its mouth there’s nothing. There are absolutely no teeth.”
Incredibly, the narwhal’s only visible tooth is outside of its mouth. Its tusk, in fact, is a giant canine tooth—that can grow as long as 9 feet—with a distinct left-hand spiral, covered in a tissue called cementum, normally only found around the base of a tooth lodged in bone.
Link (Photo: Martin Nweeia)
You know what Narwhal's tusk is good for? This.