Meeting Abstract

P3.131  Friday, Jan. 6  The very high metabolic costs of engulfment by lunge-feeding Rorquals, as revealed by computer simulations POTVIN, J.*; GOLDBOGEN , J. A.; SHADWICK, R. E.; Saint Louis University; Cascadia Research Collective; Univ. of British Columbia

Lunge feeding by rorqual whales represents one of the most extreme feeding methods among aquatic vertebrates. The strategy requires the momentary abandonment of the body-streamlining that make their non-feeding locomotion so energy-efficient, in favor of a high-drag, mouth-open configuration aimed at engulfing the maximum amount of prey-laden water. Over the past three years the Basic Lunge Feeding model (BLF) (Potvin et al. 2009 J. Roy. Soc. Interface & 2010 J. Theor. Biol) has been used to calculate for the first time the energetic cost of engulfment in comparison with the energetic gain from food (Goldbogen et al. 2011 J. Exp. Biol.), and with losses incurred during prey-approach and while purging the water out of the cavity post-engulfment (Goldbogen et al. 2011 Funct. Ecol.). The BLF has been used also as part of a new foraging model of blue whales (Balaenoptera musculus) in the specific ecology of the Southern Ocean (Weidenmann et al. 2011 Ecol. Model.). Here the BLF (V3.0) is used to show how demanding engulfment is metabolically, in comparison with (non-feeding) swimming and diving. The simulations reveal that the rate of engulfment metabolic energy expenditures (EMEE) is larger by factors of up to 40 in comparison to the basal metabolic rate (BMR). Most interestingly, EMEE are ten times greater than what is expected from the standard field and active metabolic rates (FMR and AMR, respectively) associated with a variety of marine mammal species. The BLF is also used to explore the scaling of EMEE over the body sizes of humpback (Megaptera noveaangliae), fin (Balaenoptera physalus) and blue whales. The result is that EMEE are significantly lower for the smaller adults of each species, and as such could have represented an important driver for the evolution of filter feeding in (small) archaic whale species.