Applied Technology
Several methods of applied technology have been used for the first time in this study to describe narwhal anatomy, histology and cellular structure. Among the technologies are electroencephalography, infrared reflectance microspectroscopy mapping, scanning electron microscopy, CT, micro CT and MRI imaging, T-Scan laser surface scanning, cryogenics and the use of an eight channel remote tusk sensors.
Encephalography, or EEG as it is commonly abbreviated, was utilized on expedition to record brain activity during the introduction of sensory information. Since corresponding responses to stimuli are difficult to quantify and qualify in a whale, such technology may provide the only window of opportunity to understand and associate a cause and corresponding effect. Though this technology has extensive application in the study of brain associated diseases in humans, its use in cetacean studies is far more limited and unknown in the study of narwhal. The Grass Telefactor 15LT portable EEG was utilized with platinum sub dermal electrodes and gold surface electrodes to gather information on brain activity during the introduction of sensory stimuli to the tusk. This may provide the most useful means of demonstrating cause and effect in such an organ.
Scanning electron microscopy is a traditional and common method of analyzing and magnifying the surface of an object. In this case, freshly harvested tusk tissue was analyzed with scanning electron microscopy and revealed a surprising result. Despite a cementum layer covering the tooth dentin along the exposed tusk, there are openings of tubules that can be seen within a layer of diatoms and algae that cover the outer cementum surface. The inner nerve and blood supply of this tooth that extends inside the full length of the tusk in adolescent narwhal, has extended this network of connecting tubules to the outer environment. The resulting finding from the SEM analysis is that the narwhal tusk has a vast sensory network to the outer Arctic water.
Imaging provides a unique three dimensional view of the narwhal. CT scanning completed at the Ketten Laboratory, Woods Hole Oceanographic Institution and by Ethan Tyler at the Johns Hopkins Medical School Imaging Center provides unique images of anatomic relationships that can be viewed as 3D images or animated to show layers of tissue and their interrelationship based on density. CT and MRI imaging will be completed on male and female heads of already deceased whales. These images will provide valuable insight into narwhal anatomy and internal relationships of organs and tissue. Likewise, the use of a micro CT which analyses hard tissue at a much higher resolution was used to provide images of an internal hard tissue structure found with the base of the pulpal tissue of one tusk. Evidence shows this structure to be possibly a dentinal pearl that can be found in other mammals including humans. The micro CT allows visual detail of this structure and permits the viewer to help discern its origin. Laser surface scanning was completed at Optimal CAE in Detroit, Michigan using the T-Scan from Steinbichler Optotechnik developed in Germany. By correlating millions of points on multiple planes of three dimensional tusk and skull samples, the team was able to reconstruct a highly accurate three dimensional surface model. This technology, though routinely used in the automotive industry, was unique in this research. The only two other applications for research use were 1) to analyze NASA space shuttle parts for imperfections and 2) to assist in the assembly of Sue, the Tyrannosaurus Rex featured at the Field Museum in Chicago. Animation and reconstruction of these samples brought from the Smithsonian Marine Mammal Collection revealed hidden patterns of spiraling in the tusk anatomy and also revealed anatomic relationships that could be studied and measured at remote locations. After the spiral forms are highlighted, these images can be sent to mathematicians for further analysis and mathematical modeling.
Cryogenics enables the researcher to preserve and study cells as they were at the time of collection. The advantages of such study are inherent in the method of preservation. Traditional preservation with 10% formalin or alcohol affects and alters structures though they can last for years and still be utilized in analysis. Cryogenics, however, allows the study of cells as they were, unaltered and exact in their living state. Collection of tissue with a dry shipper containing liquid nitrogen was completed on expedition in 2003.
Sensors attached to the tusk of living narwhal can gather data of interest as the whale moves. Features such as speed, light, oxygen content of the water, salinity and three dimensional positioning can be gathered at one second intervals for a pre-set time and later retrieved for analysis. Two such sensors were deployed on expedition in 2005 and will be utilized again to gather information about the whale that can relate to other information gathered based on anatomical and histological studies.
All of these technologies are useful to analyze the narwhal and integrate to other fields as they can provide insight into the description of form and function.
