Meeting Abstract

P1.120  Saturday, Jan. 4 15:30  Ecomorphological and behavioral analysis of lunge feeding and niche partitioning in rorqual whales GOLDBOGEN, JA*; FRIEDLAENDER, AS; POTVIN, J; Stanford University; Oregon State Univ; Saint Louis Univ jgoldbogen@gmail.com

Rorqual whales (Balaenopteridae) represent the third most speciose family of extant cetaceans and occupy diverse trophic niches worldwide. With the exception of Megaptera (humpback whales), rorqual species within Balaenoptera are generally similar and superficially appear as scaled facsimiles of one another. Therefore, the mechanical scaling effects of body size have been invoked to characterize the performance envelope of a given rorqual species with respect to foraging capacity. However, this assumption has not been tested directly and fine-scale morphological as well as behavioral differences may significantly affect these interconnected biological processes. We performed comparative phylogenetic analyses of morphological dimensions related to locomotor performance and engulfment capacity across the full body size range of rorqual species. Although mass-specific engulfment capacity (or Engulfed Mass Ratio (EMR): engulfment capacity divided by body mass) was positively allometric (both within and across species) and generally increased with body size (ranging from 0.3 in minke whales to 1.7 in blue whales), each species inhabits a unique morphospace. Interestingly, several species that are capable of high EMR appear to reach a common maximum (1.7 in the largest Bryde’s, sei, fin, and blue whales) that may reflect an anatomical limit related to the allometry of the ventral groove blubber as well as the skull. Using hydro-mechanical models of engulfment and best knowledge of lunge feeding kinematics from tag data, we provide an estimate for the performance envelope and energetic scope of balaeopteridae. Our analyses provide new insights into rorqual prey preferences, ecological niche, life history, and body size evolution.