Oral cavity hydrodynamics and drag production in Balaenid whale suspension feeding

Potvin, J; Werth, Alexander J.

doi:10.1371/journal.pone.0175220

Cited by 27 publications

(50 citation statements)

References 33 publications

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“…While the baleen area primarily affects drag forces and the outflow speed after water is filtered through the baleen (Potvin & Werth, ; Werth & Potvin, ; Werth et al, ), the mouth opening area affects the inflow volume of prey‐laden water. The trade‐offs in the relationship between mouth friction drag, area and speed have been illustrated by Potvin and Werth (); we present the estimated open‐mouth friction drag relative to bowhead whales (i.e. scaled by gape area) and put these values in context with their resulting filtration rates (Figure a).…”

Section: Discussionmentioning

confidence: 99%

“…After obtaining prey via an efficient cross-flow filtration system (Potvin & Werth, 2017;Sanderson, Roberts, Lineburg, & Brooks, 2016), accumulated prey must be swallowed; pausing filtration to swallow has been observed in other ram filter feeders ranging in size from basking and whale sharks (Figure 9; Motta et al, 2010;Nelson & Eckert, 2007;Sims, 2000b) to paddlefish (Sanderson, Cech, & Cheer, 1994) and herring, shad, sardines, menhaden and alewife (Sanderson & Wassersug, 1990). Hallacher (1977) and later Sims (2000b) noted pauses in the open-mouth feeding behaviours of basking sharks, with ~3 s interruptions to swallow prey.…”

Section: Previous Descriptions Of Right Whale Diving Behaviour In Deep-mentioning

confidence: 99%

“…There, 4-8 km patches of copepods with energy densities above 15 J/m 3 develop; within the large patch, concentration and energy density can vary on spatial scales of 500 m (Michaud & Taggart, 2011). To target these high densities of small prey, right whales ram filter feed as they propel themselves forward with their mouths agape (Goldbogen et al, 2016;Lambertsen, Rasmussen, Lancaster, & Hintz, 2005;Potvin & Werth, 2017;Watkins & Schevill, 1976;Werth, 2001). Through cross-flow filtration, water moves parallel along the inner surface of the baleen plates, rather than perpendicular; this concentrates small (1-3 mm) copepods while slowing the overall flow of prey-laden water through the mouth, to then be swallowed (Potvin & Werth, 2017).…”

Section: Introductionmentioning

confidence: 99%

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Foraging rates of ram‐filtering North Atlantic right whales

et al. 2019

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North Atlantic right whales spend their summer months foraging primarily in American and Canadian Atlantic waters on high‐energy‐density prey. Here, they rapidly accumulate and store energy obtained within a few months to support future migrations and reproduction while fasting. High drag from their ram‐filter foraging strategy places a limit on what prey densities will be energetically efficient to target. Our understanding of the volume of prey‐laden water filtered by right whales during a dive or foraging bout, and what information they use to decide to forage or not, has been limited by the difficulties of measuring when they feed at depth, how fast they swim during continuous ram filtration and how often they might swallow accumulated prey. We used 10 DTAG deployments from right whales in the Bay of Fundy, Canada, to quantify swimming speeds and estimate the volume of prey‐laden water filtered per dive. We used the tag's inertial sensors to evaluate the timing of frequent biomechanical changes that likely indicate the truncation of continuous filtration, and whether the number or timing of these fluking bouts relates to longer feeding dives or other foraging decisions. During foraging dives, right whales descended at 1.4 (±0.2 SD) m/s and slowed to swim at 1.1 (±0.3) m/s while filtering. We found consistent pauses in the fluking behaviour of foraging right whales, every 56 (±22) s. Whales filtered on average 78 (±30) m3 of water per fluking bout and on average 673 (±201) m3 per dive. Right whales filter large volumes of water at low speeds with a high duty cycle, but require sufficiently high prey energy densities to compensate for a high‐drag foraging strategy. Closely related bowhead whales have a larger gape but swim more slowly, filtering greater volumes with lower drag. Our findings highlight that right whales acquire their energy in a relatively short period of intense foraging; even moderate changes in their feeding behaviour or their prey energy density are likely to negatively impact their yearly energy budgets and therefore reduce fitness substantially. A plain language summary is available for this article.

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Section: Discussionmentioning

confidence: 99%

Section: Previous Descriptions Of Right Whale Diving Behaviour In Deep-mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Foraging rates of ram‐filtering North Atlantic right whales

et al. 2019

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“…The hydrodynamic mechanisms by which baleen filters seawater remain unknown, though recent work by Werth and Potvin () and Potvin and Werth () has illuminated the likely filtration process used by balaenids. Their work suggests that right and bowhead whales use cross‐flow filtration rather than sieve, or throughput, filtration.…”

Section: Introductionmentioning

confidence: 99%

“…Cross‐flow filtration (CFF) and vortical cross‐step filtration (Sanderson et al, ) have also been identified in bony fishes (Cheer et al, ; Brainerd, ; Sanderson et al, ) and elasmobranchs (Paig‐Tran et al, ; Paig‐Tran and Summers, ). Balaenid whales feature both morphological and behavioral adaptations that create the necessary pressure gradients to enable and support CFF during the continuous forward motion of the animal while feeding (Werth and Potvin, ; Potvin and Werth, ).…”

Section: Introductionmentioning

confidence: 99%

Comparative Three‐Dimensional Morphology of Baleen: Cross‐Sectional Profiles and Volume Measurements Using CT Images

Jensen

Saladrigas

Goldbogen

2017

The Anatomical Record

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Baleen whales are obligate filter feeders, straining prey‐laden seawater through racks of keratinized baleen plates. Despite the importance of baleen to the ecology and natural history of these animals, relatively little work has been done on baleen morphology, particularly with regard to the three‐dimensional morphology and structure of baleen. We used computed tomography (CT) scanning to take 3D images of six baleen specimens representing five species, including three complete racks. With these images, we described the three‐dimensional shape of the baleen plates using cross‐sectional profiles from within the gum tissue to the tip of the plates. We also measured the percentage of each specimen that was composed of either keratinized plate material or was void space between baleen plates, and thus available for seawater flow. Baleen plates have a complex three‐dimensional structure with curvature that varies across the anterior‐posterior, proximal‐distal, and medial‐lateral (lingual‐labial) axes. These curvatures also vary with location along the baleen rack, and between species. Cross‐sectional profiles resemble backwards‐facing airfoils, and some specimens display S‐shaped, or reflexed, camber. Within a baleen specimen, the intra‐baleen void volume correlates with the average bristle diameter for a species, suggesting that essentially, thinner plates (with more space between them for flow) have thinner bristles. Both plate curvature and the relative proportions of plate and void volumes are likely to have implications for the mechanics of mysticete filtration, and future studies are needed to determine the particular functions of these morphological characters. Anat Rec, 300:1942–1952, 2017. © 2017 The Authors The Anatomical Record published by Wiley Periodicals, Inc. on behalf of American Association of Anatomists

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Allometric scaling of morphology and engulfment capacity in rorqual whales

Kahane-Rapport

Goldbogen

2018

Journal of Morphology

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Body length is one of the most important factors that influence organismal function and ecological niche. Although larger animals tend to have a suite of physiological advantages, such as lower mass-specific metabolic rates and lower costs of transport, they may also experience significant limitations to unsteady locomotor performance or maneuverability because of the relative scaling of control surface areas and body mass. Rorqual whales are the largest of all animals and thus represent a unique study system for understanding how animals function at the extreme of body mass. Rorquals are characterized by an engulfment-filtration foraging strategy facilitated by a complex set of morphological adaptations. We studied the scaling of key morphological structures related to locomotion and feeding in six rorqual species in a comparative framework. Our analyses show that most rorqual species exhibit positive allometry of both the control surfaces and body length, but the large scaling differences between these parameters suggest that larger rorquals will predictably suffer from decreased maneuverability and unsteady locomotor performance. However, we found that the dimensions of the engulfment apparatus also exhibit positive allometry, and thus engulfment capacity was relatively greater in larger rorquals. We posit that the allometric growth in the engulfment apparatus may be an adaptation that ameliorates the detrimental effects of large size on maneuverability. Our analyses also reveal significant differences in the scaling of mass-specific engulfment capacity among rorqual species that may reflect the evolution of unique foraging behaviors and the exploitation of divergent ecological niches.

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Oral cavity hydrodynamics and drag production in Balaenid whale suspension feeding

Cited by 27 publications

References 33 publications

Foraging rates of ram‐filtering North Atlantic right whales

Foraging rates of ram‐filtering North Atlantic right whales

Comparative Three‐Dimensional Morphology of Baleen: Cross‐Sectional Profiles and Volume Measurements Using CT Images

Allometric scaling of morphology and engulfment capacity in rorqual whales

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