Kinematics of foraging dives and lunge-feeding in fin whales

Abstract

SUMMARY Fin whales are among the largest predators on earth, yet little is known about their foraging behavior at depth. These whales obtain their prey by lunge-feeding, an extraordinary biomechanical event where large amounts of water and prey are engulfed and filtered. This process entails a high energetic cost that effectively decreases dive duration and increases post-dive recovery time. To examine the body mechanics of fin whales during foraging dives we attached high-resolution digital tags, equipped with a hydrophone, a depth gauge and a dual-axis accelerometer, to the backs of surfacing fin whales in the Southern California Bight. Body pitch and roll were estimated by changes in static gravitational acceleration detected by orthogonal axes of the accelerometer, while higher frequency, smaller amplitude oscillations in the accelerometer signals were interpreted as bouts of active fluking. Instantaneous velocity of the whale was determined from the magnitude of turbulent flow noise measured by the hydrophone and confirmed by kinematic analysis. Fin whales employed gliding gaits during descent, executed a series of lunges at depth and ascended to the surface by steady fluking. Our examination of body kinematics at depth reveals variable lunge-feeding behavior in the context of distinct kinematic modes, which exhibit temporal coordination of rotational torques with translational accelerations. Maximum swimming speeds during lunges match previous estimates of the flow-induced pressure needed to completely expand the buccal cavity during feeding.

Skull and buccal cavity allometry increase mass-specific engulfment capacity in fin whales

“…Although there are many possible explanations for this pattern (Friedlaender et al 2009), we propose an additional hypothesis which suggests that this type of vertical resource partitioning is because of the scaling of lunge-feeding energetics. However, other tag studies have shown the opposite pattern with respect to body size, where humpback whales foraged at a much shallower depth than fin whales (Goldbogen et al 2006(Goldbogen et al , 2008, albeit at different locations. Again, it is clear that more studies are needed to fully understand the effects of lunge-feeding energetics on diving behaviour.…”

“…The general isometric scaling of propulsion and control surfaces suggests that manoeuvrability and unsteady locomotor performance, such as the ability to accelerate the body during a lunge (Goldbogen et al 2006), will decrease with body size (Webb & Debuffrenil 1990;Domenici 2001). This phenomenon occurs because body mass increases with body size much more rapidly than fluke area or flipper area, both of which are proportional to lift.…”

“…Larger rorquals may be subject to these detrimental scaling effects and therefore suffer relatively higher energetic costs for lunge feeding. However, even though the basic mechanics of lunge feeding are now relatively well understood (Goldbogen et al 2006(Goldbogen et al , 2007Potvin et al 2009), little is known about how this process scales with body size.…”

Behaviour and kinematics of continuous ram filtration in bowhead whales (Balaena mysticetus)

“…During the bottom phase of U-dives, bowhead whales regularly swim with pitch angles close to zero, rendering the speed estimate unreliable at these times. Therefore, following previous studies (Fletcher et al 1996;Burgess et al 1998;Goldbogen et al 2006;Aguilar Soto et al 2008), we used the lowfrequency flow noise recorded by the tag as an alternative proxy for speed. For each tag placement, we computed the flow noise (noise power at 500 Hz band-pass filtered with a 2-pole Butterworth filter) during descents in 5 s bins along with the mean speed, in that bin derived from the mean vertical speed multiplied by the arcsine of the mean pitch angle over the same interval.…”

Evolution of hyperphalangy and digit reduction in the cetacean manus

“…We are, therefore, unable to pinpoint a direct functional consequence of digit loss alone, but the absence of a digit in tandem with a reposition of the digits, may have led to the disparate flipper shapes in mysticete taxa. The narrow and elongate flippers of balaenopterids are probably associated with swimming at high speeds needed for lunge feeding (Goldbogen et al, 2006), whereas the more broad flippers of eschrichtiids and balaenids offer a greater surface area and may aid in low speed turns in shallow lagoons (Benke, 1993). Institution and specimen USNM 500837, 500836, 500838, 500842, 500852, 504350, 504760, 550043, 550357, 500841, 500848, 504317, 504385, 504859, 550063, 550443, 550495, 571014, 571345, 571363, 571256 550179, 550180, 550217, 55020, 550837, 550368, 504461, 504468, 504469, 504498, 550182, 550218, 55021, 504462, 504494, 504499 Tursiops truncatus MMSC 94018, 941016, 571175, 571254, 571265, 571344, 571370, 571713, 571393, 571119, 571149,571096, 571065, 571019, 571133, 571150, 571204,571259, 571269, 571351, 571371, 571121, 571118,571109, 571094, 571127, 571128, 571134, 571152,941016, 571253, 571317, 571364, 571372, 571414,571136, 571093, 571101, 571077, 571030, 571153, 571147, 571154, 571173, 571161, 571167, 571172,571195, 504123, 504121, 484931, NZP-X3080, 504310, 504501, 504881, 550313, 550440, 571162,571177, 571193, 571199, 504122, 500857, 504273,504418, 504541, 550109, 550363, 504295, 504500,504836, 550309 …”