Harvard School of Dental Medicine (HSDM) researcher Martin Nweeia, DMD, DDS, has finally answered a question that has baffled the scientific community
for centuries. The narwhal, or unicorn whale, has an eight foot tooth projecting from the left side of it's jaw and now, it is known that the tooth,
or tusk, has an array of neural networks that act as a hydrodynamic sensor, that is capable of sensing everything from water temperature to water
particle density. The finding opens new avenues of research on these unusual and long misunderstood mammals.
The narwhal has a tooth, or tusk, which emerges from the left side of the upper jaw and is an evolutionary mystery that defies many of the known
principles of mammalian teeth. The tooth's unique spiral, the degree of its asymmetry to the left side, and its odd distribution among most males and
some females are all unique expressions of teeth in mammals. The narwhal is usually 13 to 15 feet in length and weighs between 2,200 and 3,500 pounds.
Its natural habitat is the Atlantic portion of the Arctic Ocean, concentrating in the Canadian High Arctic: Baffin Bay, Davis Strait, and northern
Hudson Bay. It is also found in less numbers in the Greenland Sea, extending to Svalbard to Severnaya Zemlya off the coast of Russia.
Nweeia has discovered that the narwhal's tooth has hydrodynamic sensor capabilities. Ten million tiny nerve connections tunnel their way from the
central nerve of the narwhal tusk to its outer surface. Though seemingly rigid and hard, the tusk is like a membrane with an extremely sensitive
surface, capable of detecting changes in water temperature, pressure, and particle gradients. Because these whales can detect particle gradients in
water, they are capable of discerning the salinity of the water, which could help them survive in their Arctic ice environment. It also allows the
whales to detect water particles characteristic of the fish that constitute their diet. There is no comparison in nature and certainly none more
unique in tooth form, expression, and functional adaptation.
"Why would a tusk break the rules of normal development by expressing millions of sensory pathways that connect its nervous system to the frigid
arctic environment?" says Nweeia. "Such a finding is startling and indeed surprised all of us who discovered it." Nweeia collaborated on this
project with Frederick Eichmiller, DDS, director of the Paffenbarger Research Center at the National Institute of Standards and Technology, and James
Mead, PhD, curator of Marine Mammals at the National Museum of Natural History of the Smithsonian Institution.
Results from the team's research already has practical applications; studies about the physical makeup of the tusk, which is both strong and
flexible, provide insight into ways of improving restorative dental materials. (An 8-foot-long tooth can yield one foot in any direction without
breaking). Nweeia also leads the Narwhal Tooth Expeditions and Research Investigation, founded in 2000, which combines scientific experts with Inuit
elders, who have collected notes for hundreds of years, to discover the purpose and function of the narwhal tusk.
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Most of us probably haven't spent much time pondering the narwhal or the implications of the unusual projection from its jaw, but findings such as
this certainly increase our knowledge of the evolutionary process and the remarkable effects of natural selection. Just how some animals manage to
negotiate the environment with seemingly magical abilities has interested mankind for millennia and now, in our lifetimes, we are absolutely inundated
with new findings that illuminate the majesty of nature. We are also reminded of just how limited our own senses are compared with other species and
just how remarkable we must be to have survived so long on this planet so little that we understand as instinct.
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[edit on 2005/12/14 by GradyPhilpott]