[MARMAM] New publication on morphology and evolution of whale filtration

Alex Werth awerth at hsc.edu
Tue Aug 28 12:41:27 PDT 2018


Dear MARMAM colleagues,

On behalf of my coauthors I am pleased to announce the early publication of our new paper in the Biological Journal of the Linnean Society on the morphology and evolution of mysticete filter feeding:

Alexander J. Werth, Jean Potvin, Robert E. Shadwick, Megan M. Jensen, David E. Cade, and Jeremy A. Goldbogen. 2018. Filtration area scaling and evolution in mysticetes: trophic niche partitioning and the curious cases of sei and pygmy right whales. Biological Journal of the Linnean Society, https://doi.org/10.1093/biolinnean/bly121.

Abstract: We analyzed the functional morphology and hydrodynamics of the filtering apparatus in ten species of baleen whales (Mysticeti). Our results demonstrate a clear demarcation in baleen scaling of continuous ram filter feeders (Balaenidae; right and bowhead whales) and intermittent lunge/suction feeders: rorquals (Balaenopteridae) and the gray whale (Eschrichtiidae). In addition to different scaling trajectories, filter area varies widely among taxa. Balaenid baleen has 4-5x the area of similarly-sized rorquals (by body length and mass). Filter areas correlate with morphology; lineages evidently evolved to exploit different types of patchy prey. Feeding performance data from hydrodynamic modeling and tagged whales suggest that drag forces limit balaenids, whereas time required to purge and filter engulfed water appears to limit rorquals. Because scaling of engulfment volume outpaces increases in baleen area, large rorquals must devote greater proportions of dive time to filtration. In contrast, balaenids extend dive duration, but as a trade-off are limited to slow engulfment speeds and therefore can only target prey with low escape capabilities. The sei whale, Balaenoptera borealis, has a mid-range filter reflecting its transitional diet and intermediate morphology, embodying generalized characteristics of both continuous ram and intermittent lunge filtration. The pygmy right whale, Caperea marginata, has a balaenid-type filter via 2D analysis, but enhanced 3D modeling shows Caperea's baleen fits better with rorquals. Allometric equations relating body and filter size address phylogenetic questions about filtration in extinct lineages, including future ancestor state reconstruction analyses. Based on baleen and body size (~5m) and skull morphology, the earliest edentulous mysticetes were likely intermittent rather than continuous filterers, with simple baleen.

If you are interested please contact me for a pre-print pdf.

Alex Werth
_______________________________
Alexander J. Werth, Ph.D.
Trinkle Professor of Biology
Hampden-Sydney College
Box 162, Hampden-Sydney, VA 23943
434-223-6326, fax 434-223-6374
http://www.hsc.edu/alex-werth

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