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Quantitative Computed Tomography of Humpback Whale ( Megaptera novaeangliae ) Mandibles: Mechanical Implications for Rorqual Lunge‐Feeding
Author(s) -
Field Daniel J.,
CampbellMalone Regina,
Goldbogen Jeremy A.,
Shadwick Robert E.
Publication year - 2010
Publication title -
the anatomical record: advances in integrative anatomy and evolutionary biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.678
H-Index - 62
eISSN - 1932-8494
pISSN - 1932-8486
DOI - 10.1002/ar.21165
Subject(s) - humpback whale , mandible (arthropod mouthpart) , anatomy , quantitative computed tomography , bone density , computed tomography , ossification , whale , biology , skull , tomography , geology , orthodontics , medicine , zoology , fishery , surgery , osteoporosis , genus , endocrinology , radiology
Rorqual whales (Balaenopteridae) lunge at high speed with mouth open to nearly 90 degrees to engulf large volumes of prey‐laden water. This feeding process is enabled by extremely large skulls and mandibles that increase mouth area, thereby facilitating the flux of water into the mouth. When these mandibles are lowered during lunge‐feeding, they are exposed to high drag, and therefore, may be subject to significant bending forces. We hypothesized that these mandibles exhibited a mechanical design (shape and density distribution) that enables these bones to accommodate high loads during lunge‐feeding without exceeding their breaking strength. We used quantitative computed tomography (QCT) to determine the three‐dimensional geometry and density distribution of a pair of subadult humpback whale ( Megaptera novaeangliae ) mandibles (length = 2.10 m). QCT data indicated highest bone density and cross‐sectional area, and therefore, high resistance to bending and deflection, from the coronoid process to the middle of the dentary, which then decreased towards the anterior end of the mandible. These results differ from the caudorostral trends of increasing mandibular bone density in mammals, such as humans and the right whale, Eubalaena glacialis , indicating that adaptive bone remodeling is a significant contributing factor in establishing mandibular bone density distributions in rorquals. Anat Rec 293:1240–1247, 2010. © 2010 Wiley‐Liss, Inc.