Research Approach

The research investigation will examine several physical characteristics of the narwhal skull, jaw and teeth. Starting with basic anatomy, the narwhal will be described using both the traditional knowledge of native peoples and the scientific method. Comparisons will be made with existing studies (Reeves and Tracey, 1980; Vogl and Fischer, 1982; Pilleri, 1983). Odontocetes are characterized by skull asymmetry differentiated from the more symmetric skulls of mysticetes. Since skull asymmetry may be linked to acoustic function (Mead, 1975; Gaskin, 1982), detailed anatomic study of skull and tooth asymmetry in the narwhal will be described. CAT head scan analysis at the Woods Hole Oceanographic Institution will document a detailed anatomic record of adult male and female narwhal. Observations from these scans will elucidate the sensory possibilities of the tusk as we will be able to detect nerve connections between the tooth and the brain. Photometric data is currently being collected on museum skeletal collections at the Smithsonian Institution, The Museum of Nature in Ottawa, and the Zoological Museum in Copenhagen.We have completed photographing the collection at The Smithsonian and are now in the process of obtaining photographic print records from the Zoological Museum in Copenhagen to be converted to digital scans. We have also begun preliminary analysis of the collections at the Museum of Nature in Ottawa. Skull foramen patterns will be examined in an attempt to classify narwhal by sex and by the various expressions of teeth. Although prior efforts have been made to classify the sex of a whale based on the foramen patterns in the skull, most have proven unreliable. Since sample size may influence the predictability of these findings, we are examining over 90 narwhal skulls.Past literature has also been vague on the broad anatomic categories of adult narwhal.;Based on our collection of scientific data, and our recorded video and audio interviews with Inuit elders in 2003, we will present adult categories based on tooth expression, body size, and color patterns. These will be compared with the classification descriptions of Greenlandic Eskimos (Rosing, 1999).

The helix of the narwhal tusk will be examined by T-scan, a laser surface scan developed by Steinbechler Optotechnik in Germany. Museum specimens from the Smithsonian and the Harvard Museum of Comparative Zoology will be sent to their American office in Detroit for analysis.In addition, silicone molds will be made of male tusks from museum and private collections. From these, acrylic models will be fabricated representing morphologic variations in tusk helices.The scans and models will be evaluated by one of our collaborators to compare with other spirals and helices in nature.

Some histology of narwhal teeth and their associated soft tissue has been reported (Boyde, 1980; Hay, 1980; Brear et al., 1990; Brear et al., 1993). Among the findings noted are a lack of enamel (Ishiyama, 1987) and a thin cementum layer evident in the erupted tusk. Measurements of strength, flexibility, and composition have also been reported (Brear et al., 1990). Further investigation into the microfribril and dentinal tubule patterns of narwhal dentin will be examined by collaborators at Harvard Medical School and Children's Hospital in Boston. Cross-sectional and longitudinal tooth sections will be prepared with a low speed Buehler isomet circular diamond saw (Nelson and Ahmed, 1976; Kosick, 1979) and polished with waterproof Carborundum papers and examined under the electron microscope (Perrin and Myrick, Jr., 1980). A new technology, described as infrared electron microscopy, will map the crystalline structure within the narwhal tusk. One of our collaborators, Dr. Fred Eichmiller, Director of the Paffenbarger Research Center at the National Institute of Science and Technology, will examine thin sections of narwhal tusk utilizing this technology. From this mapping, we will be able to comment on growth patterns and crystalline composition along the tusk.

Cryogenic tissue preservation using liquid nitrogen will be used on expedition in 2004 to gather cell cultures of tooth forming cells that will be examined in the laboratory. Using a combination of established protocols (Whitehead Institute, MIT), tests conducted in the laboratory (Enders Research Facility, Children's Hospital/Harvard Medical School) and field experience on expedition in 2003, an expedition protocol for 2004 has been established.  Samples placed in a liquid nitrogen dry-shipper will be transported to laboratories at The Forsyth Institute and the Department of Orthopaedic Surgery, Children's Hospital, Boston.It should be noted that the Principal Investigator is certified in the handling and shipping of hazardous materials.Tissue collection in this study involves one of the most extensive applications of knowledge for an investigator to both collect, handle and ship tissue preserved specimens during field research. As IATA regulations for shipping and transport of hazardous materials are exacting and rigorous, such training was imperative and proved successful in the transport of tissue samples in 2003. The tusk will be examined as a sensory probe. Although there have been isolated accounts of the narwhal tusk considered as a sensory organ (Best, 1972), no one, to our knowledge, has conducted conclusive tests to support such a theory. Because of the unusual tusk helix, dentinal crystal patterns formed during development may contribute to a Piezo effect (Bassett and Becker, 1962; Kay et al., 1964; Freeman, 1966; Shamos and Levine 1967) defined as an electrical potential created from the distortion or stress of atoms within a crystal. There exists precedence in other aquatic fauna such as the paddle fish (Wojtenek et al., 2001) and platypus (Fjallbrant et al., 1988) for electric and electromagnetic fields to influence the feeding habits of these species.The possibility of the tusk as a transmitter or receiver of sound will also be explored (Harding and Harker, 1998). Field observations of captive narwhal support the possibility of tusk sound transmission from accounts of vibrations felt along the tusk during vocalizations (Best, 1972). Aerial photographs and field observations reveal a tusk emergence angle diverging from the midline of the body axis in both a horizontal and vertical plane.The male tusk position places a drag on the whale during movement but may be suited for sensory function.