Title: BBC - Earth - The tusks of narwhals are actually teeth that are inside-out
Headings: The tusks of narwhals are actually teeth that are inside-out
The tusks of narwhals are actually teeth that are inside-out
Content: Maybe it is an aggressive weapon for narwhal-narwhal battles, or for fending off predators. It could also be an icebreaker, a digging tool, or a way to show off to females. To solve this puzzle, Nweeia has assembled a team that includes marine and developmental biologists, comparative zoologists, dentists, and orthopedic surgeons. In a 2014 study that is perhaps the most detailed and high-tech analysis of the tusk ever attempted, they concluded that it is a highly sensitive organ. View image of Narwhals (Monodon monoceros) are the "unicorns of the sea" (Credit: Eric Baccega/NPL)
"This tooth is almost like a piece of skin in the sense that it has all these sensory nerve endings," says Nweeia. That is not seen in other mammalian teeth except when they are diseased. In all the encounters I've had with them, they are beautiful… and quite graceful
The narwhal tusk is "essentially built inside out," says Nweeia. Unlike our own teeth, it is soft on the outside, and gradually gets hard and dense on the inside. Nweeia's team showed that the tusk can sense changes in the salinity of the water, suggesting that it is a giant, antennae-like sensor.