JEB desktop wallpaper calendar 2016

JEB desktop wallpaper calendar 2016

Keeping momentum with a mouthful of water: behavior and kinematics of humpback whale lunge feeding
Malene Simon, Mark Johnson, Peter T. Madsen


Rorqual baleen whales lunge feed by engulfment of tons of prey-laden water in a large and expandable buccal pouch. According to prior interpretations, feeding rorquals are brought to a near-halt at the end of each lunge by drag forces primarily generated by the open mouth. Accelerating the body from a standstill is energetically costly and is purported to be the key factor determining oxygen consumption in lunge-feeding rorquals, explaining the shorter dive times than expected given their sizes. Here, we use multi-sensor archival tags (DTAGs) sampling at high rates in a fine-scale kinematic study of lunge feeding to examine the sequence of events within lunges and how energy may be expended and conserved in the process of prey capture. Analysis of 479 lunges from five humpback whales reveals that the whales accelerate as they acquire prey, opening their gape in synchrony with strong fluke strokes. The high forward speed (mean depth rate: 2.0±0.32 m s−1) during engulfment serves both to corral active prey and to expand the ventral margin of the buccal pouch and so maximize the engulfed water volume. Deceleration begins after mouth opening when the pouch nears full expansion and momentum starts to be transferred to the engulfed water. Lunge-feeding humpback whales time fluke strokes throughout the lunge to impart momentum to the engulfed water mass and so avoid a near or complete stop, but instead continue to glide at ~1–1.5 m s−1 after the lunge has ended. Subsequent filtration and prey handling appear to take an average of 46 s and are performed in parallel with re-positioning for the next lunge.



    M.S. was funded by the Oticon Foundation and Ministry of Education, Research and Nordic Cooperation, Greenland Government, Greenland Self Government. P.T.M. was funded by Steno and frame grants from the National Danish Science Foundation. M.J. was funded by National Ocean Partnership Program (NOPP) and Strategic Environmental Research and Development Program (SERDP) grants.


    total acceleration measured by the tag in three axes, A=[ax,ay,az]T; axes x, y and z are defined as the caudal–rostral, ventral–dorsal and left–right, respectively
    specific acceleration vector
    sensor sampling interval (s)
    acceleration due to gravity (9.81 m s−2)
    gravitational acceleration vector (g); G=[0,0,1]T in a {north,west,down} coordinate system.
    minimum specific acceleration (m s−2)
    direction cosine matrix describing the instantaneous orientation of the whale with respect to the inertial frame
    time (s)
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