Meeting Abstract

P3.134  Wednesday, Jan. 6  Skull and buccal cavity allometry increase mass-specific engulfment capacity in fin whales GOLDBOGEN, J. A.*; POTVIN, J.; SHADWICK, R. E.; Univ. of British Columbia; Saint Louis University; Univ. of British Columbia jgoldbogen@gmail.com

Rorqual whales (Balaenopteridae) represent not only some of the largest animals of all time, but they also exhibit a wide range in intraspecific and interspecific body size. Balaenopterids are characterized by their extreme lunge feeding behavior, a dynamic process that involves the engulfment of a large volume of prey-laden water at a high energetic cost. To investigate the consequences of scale and morphology on lunge feeding performance, we determined allometric equations for fin whale body dimensions and engulfment capacity. Our analysis demonstrates that larger fin whales have larger skulls and larger buccal cavities relative to body size. Together, these data suggest that engulfment volume is also allometric, increasing with body length as L_body^3.5. The positive allometry of the skull is accompanied by negative allometry in the tail region. In contrast, the body dimensions associated with propulsion and control surfaces were largely isometric, which should decrease maneuverability in larger rorquals. The relative shortening of the tail may represent the cost of investing all growth related resources in the anterior region of the body, thereby increasing engulfment capacity. Although enhanced engulfment volume will increase foraging efficiency, the work (energy) required to accelerate the engulfed water mass during engulfment will be relatively higher in larger rorquals. If the mass-specific energetic cost of a lunge increases with body size, then it could have major implications for rorqual ecology and evolution.