1. Objectives


The tusk was examined as a sensory organ based on observations. First, sound and vibration transmission in the tusk have been noted (Best, 1972). Second, the unique tusk emergence angle, pointing downward and outward from the whale’s longitudinal axis, suggests possible sensory function. Third, 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).

2. Preparations

Three experiments were prepared for field research. The first was the attachment of a tusk sensor, a small electronic unit housed in a casing roughly 1” by 1” by 2”. Information gathered was transferred by wireless communication to a logging unit attached to the body of the whale. The logging unit was retrieved after several hours and one logging unit was successfully retrieved. Mat Laibowitz at MIT’s Media Lab under Dr. Joseph Paradiso designed and fabricated the electronic boards for the sensor and logging unit.

The second study included recording narwhal vocalizations during captivity. An array of two hydrophones was placed a few inches from the tip of the tusk in males and roughly one meter in front of females. The hydrophones were placed in a vertical plane in line with the sound producing area of the melon and in the area of the tusk. Two males and two females were recorded.

The third experiment involved recording brain and tusk electrical activity with an EEG. Astromed, Inc., Grass-Telefactor Division loaned a portable unit that connected a montage of 8 electrodes for the brain and 4 electrodes for the tusk. Montage positions were chosen from relative surface skin to brain locations as seen and documented from CT scans of frozen head specimens examined.

3. Observations

Several results are noteworthy. The first is a blast of energy and general numbing sensation that was felt on my right leg when I was in the water and directly in front of the fourth female narwhal captive during a sound recording. None of the other team members have experienced this sensation before and proposed that it could be a high frequency blast of sound. Initial speculation suggests this sensation may be due to a non linear interaction of high frequency waves to generate a type of sound pressure. Joseph Pompei, formerly at the MIT Media Lab, has done extensive work in this area which may be linked to this whale. There is only speculation on how narwhal catch their prey and although a "stun effect" has been hypothesized, no one has had any definitive results. Collecting information from a position directly in front of the whales allowed the possibility of this unique experience. Since I was recording with two hydrophones at the time of this event, there may be some insight into its origin and cause. Results of the tusk sensor will be analyzed in a future paper. The EEG studies were not able to be performed as sea and weather conditions were not appropriate for the safe use of the equipment. Continued studies will be attempted in 2005.