Beaked Whale Anatomy, Field Studies and Habitat Modeling

This report describes the results of two tasks related to the study of beaked whales. The first study was a field study of beaked whales in the Gulf of California from December 2004 to December 2006. The goal of the study was to determine the range of sound produced by beaked whales and to investigate beaked whale behavior and habitat. A minimum of 17 cetacean species 12 toothed and 5 baleen whales were observed in 147 sightings. The proportion of sighted toothed whales and baleen whales was 67 and 32, respectively. The second task was the modeling of beaked whale anatomy, the conversion of anatomy to physical properties, and the use of these in a finite element model of the effects of intense sound. To validate their methodological procedures, the authors compared CT data from live, frozen, and thawed specimens of Tursiops truncatus. The results showed that CT scans produce similar results in tissues and organs for the following quantities geometry, absolute density, and sound velocity across live and thawed specimens. Simulated sound sources placed inside and outside of a modeled adult male beaked whale Ziphius cavirostris revealed pathways for acoustic propagation into and out of the head. This result supports the notion that dual sonar sources interfere constructively to form a sonar beam in front of the animal. The simulations also indicated a new gular pathway for sound reception. Propagated sound pressure waves enter the head from below and between the lower jaws, continuing toward the bony ear complexes through the internal mandibular fat bodies. The report titles produced through these studies are as follows Vocalizations and Marine Habitat of Baleen and Beaked Whales, by Gustavo Cardenas, Jorge Urban, and Alejandro Gomez-Gallardo and Simulated Sound Transmission and Reception in Cuviers Beaked Whale Ziphius Cavirostris Using the Vibro-Acoustic Toolbox, by Ted W. Cranford, Petr Krysl, and John A. Hildebrand.