Measuring up to 2.7 meters or about 9 feet long, the tusk is traversed by up to 10 million nerve pathways. These pathways connect the outside of the tusk to a central core of nerves leading to the animal's brain. Based on experiments with samples of the tusk as well as with a captured narwhal whale, the research team found that the tusk's sensory system may be capable of detecting changes in temperature, pressure, salinity and other factors that may help a narwhal survive its Arctic environment.
Working at NIST, Naomi Eidelman, Anthony Giuseppetti and Frederick Eichmiller of the ADAF examined samples of narwhal tusk with both infrared microspectroscopy and scanning electron microscopy. Their work revealed the tusk's unusual structure.
While most mammalian teeth are softer on the inside and harder on the outside, narwhal tusk appears to be made "inside out," says Eichmiller. The researchers believe the softer outer layers of the tusk may act like a shock absorber to help prevent breaks.
Contact: Mark Bello
National Institute of Standards and Technology (NIST)