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Big Gulps require high drag for fin whale lunge feeding

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Fin whales Balaenoptera physalus exhibit one of the most extreme feeding methods among aquatic vertebrates. Fin whales, and other rorquals (Balaenopteridae), lunge with their mouth fully agape, thereby generating dynamic pressure to stretch their mouth around a large volume of prey-laden water, which is then filtered by racks of baleen. Despite their large body size, fin whales appear to be limited to short dive durations, likely because of the energetic cost associated with large accelerations of the body during several lunges at depth. Here, we incorporate kinematic data from high-resolution digital tags and morphological data of the engulfment apparatus in a simple mechan- ical model to estimate the drag acting on a lunge-feeding fin whale. This model also allowed us to quantify the amount of water and prey obtained in a single lunge. Our analysis suggests that the reconfiguration and expansion of the buccal cavity enables an adult fin whale to engulf approxi- mately 60 to 82 m3 of water, a volume greater than its entire body. This large engulfment capacity, however, comes at a high cost because the drag, work against drag, and drag coefficient dramatically increase over the course of a lunge. As a result, kinetic energy is rapidly dissipated from the body, and each subsequent lunge requires acceleration from rest. Despite this high cost, living bal- aenopterids are not only among the largest animals on earth, but are relatively speciose and exhibit diverse prey preferences. Given this ecological diversity, we frame our results in an evolutionary con- text, and address the implications of our results for the origin of lunge feeding.
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MARINE ECOLOGY PROGRESS SERIES
Mar Ecol Prog Ser
Vol. 349: 289– 301, 2007
doi: 10.3354/meps07066 Published November 8
INTRODUCTION
Baleen whales (or Mysticeti) are highly streamlined
marine mammals that have evolved an efficient loco-
motor strategy (Williams 1999), which permits high-
speed swimming as well as long-distance migration.
Mysticetes also rank among the largest vertebrates of
all time, and they differ from their sister taxon, the
toothed whales (or Odontoceti), by the presence of ker-
atinized baleen plates that hang from the rostrum and
serve to filter prey from a volume of ingested water.
This feeding strategy occurs in several different modes
among living mysticetes (Werth 2000): (1) benthic
suction feeding, observed only in the gray whale
Eschrichtius robustus; (2) skim or continuous ram feed-
ing, which bowhead and right whales (Balaenidae) use
exclusively; and, lastly, (3) lunge feeding, the principal
mode for rorquals (Balaenopteridae). Some mysticetes
have very specialized cranial and mandibular mor-
phologies that restrict them to one mode of feeding
(e.g. a highly arched rostrum in balaenids), whereas
other mysticetes, like gray whales, can employ differ-
ent modes as needed (Nerini 1984). Overall, filter feed-
ing in mysticetes allows these predators to process
bulk quantities of prey items at a scale commensurate
with their comparatively large body size (Sanderson &
Wassersug 1993, Werth 2000).
Lunge feeding, which is formally characterized as
intermittent ram suspension feeding (Sanderson &
Wassersug 1993), is a specific behavior documented
© Inter-Research 2007 · www.int-res.com*Email: jergold@zoology.ubc.ca
Big gulps require high drag for fin whale
lunge feeding
Jeremy A. Goldbogen1,*, Nicholas D. Pyenson2, Robert E. Shadwick1
1Department of Zoology, University of British Columbia, 6270 University Boulevard, Vancouver,
British Columbia V6T 1Z4, Canada
2Department of Integrative Biology and Museum of Paleontology, University of California, Berkeley, California 94720, USA
ABSTRACT: Fin whales Balaenoptera physalus exhibit one of the most extreme feeding methods
among aquatic vertebrates. Fin whales, and other rorquals (Balaenopteridae), lunge with their mouth
fully agape, thereby generating dynamic pressure to stretch their mouth around a large volume of
prey-laden water, which is then filtered by racks of baleen. Despite their large body size, fin whales
appear to be limited to short dive durations, likely because of the energetic cost associated with large
accelerations of the body during several lunges at depth. Here, we incorporate kinematic data from
high-resolution digital tags and morphological data of the engulfment apparatus in a simple mechan-
ical model to estimate the drag acting on a lunge-feeding fin whale. This model also allowed us to
quantify the amount of water and prey obtained in a single lunge. Our analysis suggests that the
reconfiguration and expansion of the buccal cavity enables an adult fin whale to engulf approxi-
mately 60 to 82 m3of water, a volume greater than its entire body. This large engulfment capacity,
however, comes at a high cost because the drag, work against drag, and drag coefficient dramatically
increase over the course of a lunge. As a result, kinetic energy is rapidly dissipated from the body,
and each subsequent lunge requires acceleration from rest. Despite this high cost, living bal-
aenopterids are not only among the largest animals on earth, but are relatively speciose and exhibit
diverse prey preferences. Given this ecological diversity, we frame our results in an evolutionary con-
text, and address the implications of our results for the origin of lunge feeding.
KEY WORDS: Lunge feeding · Fin whale · Balaenoptera physalus · Drag · Foraging · Locomotion
Resale or republication not permitted without written consent of the publisher
Mar Ecol Prog Ser 349: 289–301, 2007
among rorquals that allows individuals to engulf large
quantities of water and prey using a series of coordi-
nated events: (1) accelerating the body, (2) lowering
the mandibles and presenting the floor of the mouth to
oncoming flow, (3) generating dynamic pressure that
expands the buccal cavity, (4) closing the mouth
around a large volume of water, and (5) expelling this
volume through baleen plates located on the roof of
the mouth, thereby retaining prey inside the buccal
cavity.
The ingestion of water is facilitated by several key
morphological features of the rorqual feeding appara-
tus, including a highly extensible ventral groove blub-
ber (VGB) located on the ventral surface of the throat
wall that extends from the snout to the umbilicus
(Orton & Brodie 1987) and massive, unfused mandibles
that make up nearly 25% of the length of the body
(Pivorunas 1977, Lambertsen et al. 1995). These bones
have been observed to rotate during lunge feeding in
several species of rorquals (Lambertsen et al. 1995,
Arnold et al. 2005), and this phenomenon serves to
increase the area of the mouth exposed to flow (Lam-
bertsen et al. 1995) as well as to maneuver the man-
dibles around the laterally curved baleen plates (Pivo-
runas 1976, 1977). Lambertsen et al. (1995) defined 3
different degrees of freedom with respect to jaw move-
ment: (1) alpha about the long axis of the mandible,
(2) delta jaw abduction, and (3) omega lateral
divergence that occurs at the temporomandibular
joint. Ultimately, the magnitude of the engulfed vol-
ume is limited morphologically, not only by the size
and shape of the mandibles (Lambertsen et al. 1995),
but also the capacitance of the mouth provided by the
elastic VGB (Orton & Brodie 1987). The dimensions
and mechanical properties of the VGB suggest that the
expansion of the buccal cavity is driven solely by the
hydrodynamic pressure from swimming (Orton &
Brodie 1987).
The widespread convergence of a streamlined body
profile in many flying and swimming organisms
reflects the functional and evolutionary importance of
minimizing drag during locomotion (Vogel 1994). Such
shape dependence on drag reduction has major impli-
cations for any organism that must deviate from this
ideal form in order to perform life functions. As adept
swimmers, rorquals possess highly streamlined bodies
powered by flukes with a high aspect ratio, and these
morphological specializations are predicted to enable
efficient and high-performance locomotion at high
speeds (Bose & Lien 1989). When rorquals lunge feed,
however, the process and result of engulfment forces a
severe departure from the streamlined paradigm,
where the body takes on a distended and bloated
shape. It has been hypothesized that lunge feeding
entails a high energetic cost, probably due to the drag
created by an open mouth at high speeds (Croll et al.
2001, Acevedo-Gutierrez et al. 2002). Recent tagging
efforts that have elucidated the detailed kinematics of
the body during lunges in fin whales (Goldbogen et al.
2006) demonstrated that fin whales routinely execute
several lunges per dive at depths >200 m. Most
notably, each lunge was characterized by a rapid
deceleration of the body despite continued swimming
(Goldbogen et al. 2006). Together, these lines of evi-
dence suggest a high cost associated with lunge feed-
ing in rorquals due principally to high drag.
Among diving birds and mammals, diving capacity is
predicted to increase for larger organisms because of
the differential scaling between blood oxygen stores
and metabolic rate (Butler & Jones 1982). Although this
scaling relationship does hold across many diverse and
independent lineages, it is severely affected by ecolog-
ical, behavioral and physiological factors (Halsey et al.
2006). For example, blue whales Balaenoptera muscu-
lus and fin whales are the largest diving animals, but
they do not exhibit the deepest or the longest dive
durations (Croll et al. 2001). Instead, the maximum
dive durations for blue and fin whales are only 15 to
17 min, less than half the time predicted for their com-
paratively large body sizes (Croll et al. 2001). Similar
maximum dive durations have been observed even for
consecutive dives to >400 m (Panigada et al. 1999).
The energetic cost of lunge feeding has been sug-
gested to be a likely constraint that severely limits for-
aging time and increases post-dive recovery time at
the sea surface (Acevedo-Gutierrez et al. 2002). In con-
trast, the continuous skim feeding in right and bow-
head whales (Balaenidae), the sister group to rorquals
and just as massive, does not appear to be constrained
by high feeding costs. Balaenid foraging dives are
twice as long as most rorquals’, even at equivalent
depths, and their dives are followed by shorter recov-
ery times at the surface (Krutzikowsky & Mate 2000).
This dichotomy can be attributed to the energetic
demands of different feeding strategies between
balaenids (continuous ram feeders) and balaenopterids
(intermittent lunge feeders) (Croll et al. 2001,
Acevedo-Gutierrez et al. 2002).
Although the current data on rorqual foraging are
consistent with the hypothesis that lunge feeding is
energetically expensive, the actual cost has not been
addressed quantitatively. Furthermore, the details
regarding the benefit of lunge feeding, such as engulf-
ment capacity, are largely unknown. To test the hypo-
thesis that lunge feeding requires drag, we developed
a mechanical model of engulfment for a lunge-feeding
rorqual based on mechanical principles and hydrody-
namic theory. Additionally, we incorporated kinematic
data recorded from high-resolution digital tags and
morphological data of the engulfment apparatus into
290
Goldbogen et al.: Fin whale lunge feeding
the model to quantify engulfment volume and net drag
for a lunge-feeding fin whale. We then discuss the
implications of our results in the context of fin whale
foraging ecology and evolution.
MATERIALS AND METHODS
Mechanics of the body during lunge feeding. Tag
deployments on fin whales Balaenoptera physalus
revealed the average speed of the body (for 50 lunges,
7 adults) at 1 s intervals (Goldbogen et al. 2006); speed
of the body was determined by flow noise detected by
the hydrophone within the tag and also independently
checked for accuracy by kinematic analysis. Average
speed and a range corresponding to 2 standard devia-
tions about the mean were incorporated into the model
that follows (Fig. 1). In this way, the model accounts for
68% of the variation in lunge speed observed by
tagged fin whales. The derivative of speed with
respect to time provided the acceleration profile
needed for the hydrodynamic analyses in the present
study.
The average body length Lis approximately 20 m for
an adult fin whale (Lockyer 1976). This body length
was used in order to select other morphological para-
meters (Table 1) that correspond to the fin whales that
were tagged.
Engulfment volume. The volume of water engulfed
within a given time increment Viis equal to the prod-
uct of instantaneous projected mouth area SMand the
distance traveled during that time increment Δx/Δt:
Vi= SMΔx/Δt(1)
The cumulative engulfed volume VEis the sum of Vi.
Displacement of the body during the lunge was calcu-
lated by integrating the area under the velocity profile.
This model assumes that the VGB expands rapidly
enough so that no spill-over takes place during engulf-
ment.
291
Time (s)
0 2 4 6 8 10 12 14 16 18 20
Speed (m s
–1
)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
Acceleration (m s
–2
)
–0.6
–0.4
–0.2
0.0
0.2
0.4
0.6
Fig. 1. Balaenoptera physalus. Kinematics of the body during
a lunge. Average speed of the body (black line) calculated for
50 lunges performed by 7 fin whales (see Goldbogen et al.
2006). Error bars represent 2 standard deviations about the
mean. Acceleration of the body (gray line) is calculated from
the change in speed over each 1 s interval. The vertical,
closely dashed line represents the moment when the mouth
opens at maximum speed, and the vertical, widely dashed
line marks the moment of greatest deceleration, which should
occur at maximum gape
Table 1. Parameters incorporated into the model. All morphological and physiological parameters correspond to an adult
fin whale where the body length (L) = 20 m. Plus or minus symbols represent one standard deviation
Parameter Symbol Value Reference
Average adult body length L20 m Lockyer (1976)
Average adult body mass M50 000 kg Lockyer (1976)
Length of ventral grooves LV8 m (0.4L) Orton & Brodie (1987
Radius of the body R1.5 m Lockyer & Waters (1986)
Body speed Usee Fig. 1 Goldbogen et al. (2006)
Projected mouth area as a SMsee Fig. 3 Lambertsen et al. (1995)
function of gape angle
Baleen filter area AB3.0 m2Kawamura (1980)
Baleen fringe diameter LFRange = 2.5 ×10–2 to 1.4 ×10–1 cm; Kawamura (1980)
Average = 7.5 ×10–2 cm
Baleen plate spacing LPAverage = 0.6 ± 0.2 cm USNM 504258, 504243;
MVZ 124428; UCMP 85366
Prey density (krill) PDAverage = 0.15 kg m–3 Croll et al. (2005)
Daily energetic demand (krill) Γ901 ± 258 kg d–1 Croll et al. (2006)
Average foraging dive duration (TD+ TS) 9 min Croll et al. (2001); Acevedo-
and surface recovery time Gutierrez et al. (2002);
Goldbogen et al. (2006)
Duration between consecutive lunges at depth TLAverage = 30 s Goldbogen et al. (2006)
Number of lunges per dive NoAverage = 4 Goldbogen et al. (2006)
Mar Ecol Prog Ser 349: 289–301, 2007
The average duration between consecutive lunges
TLeffectively represents the time required to filter the
engulfed volume (Goldbogen et al. 2006). Although
the actual filter time could be faster, the whale proba-
bly executes another lunge as soon as the previously
engulfed volume has been filtered given that dive time
is limited. Thus, volumetric flow rate or filter rate Fis
then defined as:
F= VE/TL(2)
If Fis distributed over the baleen filter area ABfor a
20 m fin whale (Kawamura 1980; Table 1), we can
define an average flow speed of the engulfed water
being filtered by the baleen as:
O
ˇ= F/AB(3)
Furthermore, we can describe the character of flow
past the baleen and its fringes as described by the non-
dimensional Reynolds number Re, which is the ratio of
inertial to viscous forces:
Re= (O
ˇLX)/
ν
(4)
where LXis either the distance between consecutive
baleen plates LPor the diameter of the individual
fringes LFand
ν
is the kinematic viscosity of sea-
water. We highlight this distinction because, in
rorquals, water first flows past the fringes located on
the lingual side of the baleen, and then the water
passes through the baleen plates themselves (Werth
2001). Kawamura (1980) reported measurements
for the diameter of baleen fringes for fin whales
(Table 1). We measured the distance between con-
secutive baleen plates on the following museum
specimens at the National Museum of Natural His-
tory in Washington, DC (USNM 504258, 504243),
and the Museum of Vertebrate Zoology (MVZ
124428) and the Museum of Paleontology (UCMP
85366), both at the University of California, Berke-
ley. We only measured baleen plates that were still
intact as a series within the gum. Each specimen
was photographed with a scale bar and measured
digitally using ImageJ (freeware available at:
http://rsb.info. nih.gov/ij/).
Foraging ecology. By combining the engulfment
volume generated by the model and previously pub-
lished data for fin whales and their prey (Table 1),
we can predict several parameters that are relevant
to fin whale foraging ecology. We can calculate the
amount of krill acquired per lunge
Κ
Lfor a given
prey density PD:
Κ
L= PDVE(5)
Next, we can predict the number of lunges per day NL
required to meet a daily energetic demand Γ:
NL= Γ/
Κ
L(6)
and the number of foraging dives per day NFfor a
given number of lunges per dive No:
NF= NL/No(7)
We used previous estimates of daily energetic demand
calculated by Brodie (1975) and Croll et al. (2006). The
foraging time TFneeded to perform NFfor a continu-
ously foraging fin whale:
TF= (TD+T
S)NF(8)
is related to the time required to perform a foraging
dive TDin addition to the surface time following each
dive TS.
Projected mouth area and estimation of gape angle.
Projected mouth area SMas a function of gape angle
was previously reported for a 20 m adult fin whale
specimen (Lambertsen et al. 1995). To evaluate any
major variation in mouth area among individuals of the
same size, we calculated maximum mouth area for
2 other fin whales (USNM 550467, L= 19.7 m; and
True’s (1904: p 133) Specimen No. 6, Wister Institute,
Philadelphia, L= 20.7) following the simple geometric
calculation of Lambertsen et al. (1995). We made stan-
dardized measurements of the skull and mandibles to
determine the functional area of the mouth involved in
lunge feeding (Lambertsen et al. 1995). Each calcula-
tion was within 1.0 m2of the maximum mouth area
reported by Lambertsen et al. (1995), which is only
12% of this maximum reported value.
To determine how gape angle changes as a func-
tion of time tduring a lunge, we first measured the
angle between the tip of the rostrum and the tip of
the mandibles for a rorqual lunge feeding on school-
ing fish (BBC Video Blue Planet, Open Seas). This
video footage is arguably the best for any rorqual
lunge and serves as a vital source of information
regarding the change in gape angle over time. The
narrator in the footage identifies the individual
rorqual as a sei whale Balaenoptera borealis,
although Arnold et al. (2005), with whom we agree,
identified this individual as a Bryde’s whale Bal-
aenoptera brydei. While this individual is not as large
as a fin whale, we analyzed this data in order to
determine how gape angle changes for a lunge in
any rorqual, and then scaled the relative changes in
gape angle to be appropriate for a fin whale as sug-
gested by kinematic data from deployed tags. Despite
differences in size between Bryde’s and fin whales,
skull and mandible morphologies are very similar
(J. A. Goldbogen, N. D. Pyenson unpubl. data) and
we expect similar motions during lunge feeding as
would be predicted by dynamic similarity.
Gape angle θwas analyzed for 2 lunges in which the
body was largely perpendicular to the camera (Fig. 2a).
292
Goldbogen et al.: Fin whale lunge feeding
Each lunge was approximately 3 s in duration, from
mouth opening to mouth closure, with maximum θ
occurring half-way through the lunge at t= 1.5 s. A
quadratic spline fit to the average θdata for each lunge
revealed a bell-shaped curve. We recorded the
approximate time that the VGB started to expand and
when it nearly reached full extension. We then scaled
the gape angle profile of a Bryde’s whale (average L=
14 m, Δt= 3 s) to that of a fin whale (average L= 20 m,
Δt= 6 s) to account for a longer lunge time (Fig. 2b).
This scaling agrees with the mechanical principles of
engulfment, whereby the mouth opens at maximum
velocity and the moment of maximum deceleration
occurs at maximum gape (Fig. 1; Goldbogen et al.
2006).
It is important to note that gape angle may also be a
function of elevation of the rostrum (Arnold et al.
2005), but this is not expected to affect the model sig-
nificantly. The area of the rostrum covers a large pro-
portion of the area defined by the mandibles; thus, any
elevation of the rostrum will deflect oncoming flow into
the mouth.
Hydrodynamic and mechanical modeling. We chose
a quasi-steady hydrodynamic analysis to determine
the net drag acting on a lunge-feeding fin whale. The
mass Mof a 20 m adult fin whale (Table 1) will decel-
erate aas a function of the net drag D:
D=Ma (9)
Although there certainly is thrust generated by swim-
ming during the lunge, the total drag becomes much
greater than the thrust, which is why the body decele-
rates rapidly despite continued swimming (Goldbogen
et al. 2006). Therefore, we will not include thrust in the
present model. We obtain aby calculating the change
in speed over time from previously published measure-
ments (Goldbogen et al. 2006).
The mass of the system does not include the mass of
the engulfed volume. Explicitly leaving the engulfed
mass out of the calculation for drag is similar to leaving
out the mass of the fluid external to the body that is
accelerated, as has been done elsewhere in the
unsteady aerodynamics of accelerating (Potvin et al.
2003) or decelerating (Iversen & Balent 1951) bluff
bodies. Thus, the engulfed water is being accelerated
(and therefore creates dynamic pressure and drag),
but it is not fully accelerated to become part of the sys-
tem initially. The engulfed volume is enveloped in
place because the stretching of the VGB is rapid
enough so that the only wake that is produced is by the
rigid mandibles and exposed rostrum. The compliance
of the ventral pouch also provides some delay so that
the whale can close its mouth before water is acceler-
ated up to the speed of the whale, thus preventing a
bow wave that would push potential prey away
(Brodie 2001).
A force exerted over a distance Δxrepresents
work. Swimming against drag represents the work
against drag Wand is calculated as a product of D
and Δx:
W= DΔx(10)
We can determine the quasi-steady drag coefficient
CD, or the drag per unit area divided by the dynamic
pressure, at any given instant during the lunge:
CD=2Ma/ρSTU2(11)
293
A
B
0.0 0.5 1.0 1.5 2.0 2.5 3.0
Gape angle (deg)
0
15
30
45
60
75
90
Time (s)
0 1 2 3 4 5 6
0
15
30
45
60
75
90
Fig. 2. The amount of time required to lower and raise the
mandibles during a lunge is approximately equal. (a) Gape an-
gle (θ) measured as a function of time (t) during 2 lunges per-
formed by a Bryde’s whale Balaenoptera brydei (see ‘Materi-
als and methods’ for details). (h, n) Data points for each lunge.
Average gape angle ( ) is fit by the polynomial regression (θ=
15.353t4– 93.506t3+ 144.07t2– 5.4003t; r2= 0.994). The verti-
cal dashed line indicates maximum gape, whereas the vertical
solid lines mark the moments at which the ventral groove
blubber starts and stops expanding. (b) These data for a
Bryde’s whale (black line) were scaled with respect to time, in
order to estimate the gape angle during a fin whale lunge
(gray line) of longer duration, as indicated by kinematics of the
body (Fig. 1)
Mar Ecol Prog Ser 349: 289–301, 2007
where ρis the density of seawater, Uis the instanta-
neous speed, and STis the total projected area of the
body. Only STis considered in this model, rather than
wetted surface area, because at such high Re(Re>
107), >97% of the total drag consists of pressure drag
(Vogel 1994).
Projected area of the body is dynamic due to the
opening and closing of the jaws and the expansion of
the buccal cavity, which together augment the pro-
jected area of the ventral side of the body. Total pro-
jected area of the body is therefore determined by the
sum of ventral SVand dorsal SDcomponents of the
body represented by half-cylinders:
ST=S
V+ SD(12)
The dorsal component remains constant throughout
the lunge and is calculated as a half-cylinder with a
radius R, which is determined from previously pub-
lished measurements of an adult fin whale (Table 1). In
contrast, SVwill be determined by SMbefore maximum
gape, and by the projected area of the expanded
buccal cavity SBC after maximum gape. We can calcu-
late the instantaneous radius rof the buccal cavity
given a fixed length of the mouth or ventral grooves LV
(Table 1; Orton & Brodie 1987) and the cumulative vol-
ume VEfrom Eq. (1):
r= (2VE/πLV) (13)
Thus, before maximum gape:
SV= SM(14)
while after maximum gape:
SV= SBC = 12πr2(15)
RESULTS
Kinematics
The kinematics of the body during a lunge provided
a context for which to examine how gape angle (θ) and
projected mouth area (SM) vary as a function of time
(Fig. 3). Over a time of 6 s, the speed of the body
decreased from 3.0 to 0.5 m s–1.The mandibles were
lowered to a maximum gape θmax of approximately 80°
and raised in the same amount of time (~3 s). Similar
compliance of the temperomandibular joint was ob-
served in a wide variety of post mortem experiments in
which θmax of fin, sei, and minke whales ranged from
85 to 90° (Lambertsen et al. 1995, Brodie 2001). From
skull morphology and an accurate estimate of swim-
ming speed, Brodie (1993) predicted θmax to occur in
about 3 s, which agrees with the model presented
here.
Mandible length for an adult fin whale Balaenoptera
physalus was measured as 4.6 m, which traced a path
of approximately 14 m by the tip during engulfment.
Thus, the depression and elevation of the mandible tip
occur at a mean velocity of 2.4 m s–1 for the lunge dura-
tion presented here. These results are consistent with
those of Kot (2005), who calculated an average eleva-
tion of the mandible as 2.8 m s–1 for fin whales lunge-
feeding at the sea surface.
Changes in θwere tightly associated with changes in
SM, with both reaching maxima half-way through the
lunge. The sum of the product of forward body dis-
placement and SMover the course of the lunge resulted
in an average engulfment volume of 71 m3(range: 60
to 82 m3). The radius of the half-cylinder representing
the buccal cavity increased by 60% (range: 50 to 70%)
by the end of the lunge.
Drag
Gape angle dramatically increased the projected
area of the body and therefore strongly affected drag
on the body (Fig. 4). Maximum drag (average = 20 kN;
range: 17 to 22 kN) occurred at maximum gape. Maxi-
mum drag (t= 13.5) was approximately 4 times the ini-
tial drag (t= 10.5). The work against drag correlated
with the filling rate of the buccal cavity (Fig. 5). Maxi-
ma for work against drag (average = 44 kJ; range: 28 to
58 kJ) and filling rate of the buccal cavity (average =
20 m3s–1; range: 18 to 23 m3s–1) occurred when the
VGB started to expand. The maximum work against
drag (t= 12.5) was 3 times greater than initial values
(t= 10.5).
The drag coefficient (CD; referenced to frontal area)
increased over the course of a lunge and was positively
correlated with the amount of water engulfed (Fig. 4).
As the mouth began to open, the average CDwas cal-
culated as 0.21 (CDrange: 0.18 to 0.26). Just before the
mouth to closed, CDhad increased by at least an order
of magnitude (average = 3.21; range: 2.20 to 5.13).
Filter performance and foraging ecology
The engulfed volume was filtered at an average
rate of 2.4 m3s–1 (range: 2.0 to 2.7 m3s–1; Table 2).
This mass flow distributed over the baleen filter area
results in an average flow speed of 0.8 m s–1 (range:
0.7 to 0.9 m s–1). Consequently, the average Reynolds
number (Re) for flow past the baleen fringes was 570
(range: 480 to 650). After flowing around the fringes
located on the lingual side of the baleen, water must
next pass through the baleen plates themselves. The
average spacing between fin whale baleen plates
294
Goldbogen et al.: Fin whale lunge feeding
yields an Renumber well within the
recognized inertial hydrodynamic
regime (average = 4500; range: 3800
to 5200).
For an average prey density mea-
sured at foraging sites, a fin whale
can acquire an average of 11 kg of
krill per lunge (range: 9 to 12 kg) for
the engulfment capacity calculated
in the present study. A fin whale
would therefore have to execute an
average of 83 lunges d–1 (range: 73
to 100 lunges d–1) to fulfill its daily
energetic demands. This energetic
demand can be met by an average of
21 dives (range: 18 to 25 dives) over
an average foraging time of 3.1 h
(range: 2.8 to 3.8 h).
295
Fig. 3. Balaenoptera physalus. Relationship between gape angle (red line), projected mouth area (blue line), speed (black line)
and volume engulfed (green line) in the context of the mechanics of the body during a lunge. Vertical lines mark significant
events throughout the lunge cycle represented by each schematic: (a) mouth begins to open, (b) ventral groove blubber (VGB)
begins to expand, (c) maximum gape angle, (d) VGB is nearly fully expanded, and (e) mouth closes. The shaded area represents
the distance traveled during the lunge. Fin whale vector-based artwork adapted and modified from Folkens (2003)
Time (s)
10 11 12 13 14 15 16
Speed (m s–1)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
Gape angle (deg)
0
15
30
45
60
75
90
Dra
g
(kN)
5
10
15
20
25
30
Speed
Gape angle
Drag
abced
Fig. 4. Balaenoptera physalus. Drag correlates with gape angle. Gape angle
dramatically increases projected area of the body (Fig. 1) and therefore
becomes the main predictor of drag on the body. a– e: see Fig. 3. Error bars
represent 2 standard deviations about the mean
Mar Ecol Prog Ser 349: 289–301, 2007
DISCUSSION
This study demonstrates the extraordinary engulf-
ment capacity and associated mechanical consequen-
ces of fin whale Balaenoptera physalus lunge feeding.
We present the first testable model of this feeding pro-
cess that combines kinematic data
recorded from high-resolution digital
tags with morphological data of the
skull, mandibles, and soft tissues of the
body. Our analysis shows an increase in
drag related to the expansion and
reconfiguration of the buccal cavity
during a lunge (Figs. 4 to 6). The high
drag required to expand the mouth also
dissipates the kinetic energy of the
body, bringing the body practically to a
halt. As a result, each lunge requires
acceleration from rest and therefore
comes at a high energetic cost. This
mechanical consequence is especially
important considering that fin whales
execute up to 7 lunges dive–1 (Gold-
bogen et al. 2006). The energetic
demand of lunge feeding has been
implicated in the rapid exhaustion of
oxygen stores at depth, resulting in
very short dive durations (Croll et al.
2001). Indeed, blue and fin whales that
performed more lunges at depth also
spent a greater amount of time at the
sea surface following those lunges, pre-
sumably to replace oxygen stores (Ace-
vedo-Gutierrez et al. 2002). Our results
support the hypothesis of Acevedo-
Gutierrez et al. (2002), who first sug-
gested that the energetic cost of lunge
feeding is due primarily to drag.
Our results, along with those of
Acevedo-Gutierrez et al. (2002), dis-
agree with those of Blix & Folkow
(1995), who concluded that minke
whales Balaenoptera acutorostrata do
not show any difference in energy
expenditure between lunge feeding
and cruising. These conclusions were
based on respiratory rates, steady swim
speed estimates that were apparently
not calibrated, and subjective analysis
of dive profiles. Blix & Folkow (1995)
failed to account for changes in speed
that occur during a lunge under short
time scales; these rapid accelerations
are a better indicator of lunge feeding
than subjective analysis of dive profiles
(see Goldbogen et al. 2006). From the limited data
available on their diving behavior (Stockin et al. 2001),
it appears that minke whales also exhibit short mass-
specific dive durations much like their larger relatives.
Although it seems that lunge feeding is accompanied
by an energetic cost for all rorquals, the relative mag-
296
Time (s)
10 11 12 13 14 15 16
Speed (m s–1)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
Work against drag (kJ)
0
10
20
30
40
50
60
70
80
Filling rate (m3 s–1)
0
5
10
15
20
25
30
Speed
Work against drag
Filling Rate
abced
Time (s)
10 11 12 13 14 15 16
Speed (m s–1)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
CD
0
1
2
3
4
5
6
Volume engulfed (m3)
0
20
40
60
80
100
120
Speed
CD
Volume
cba de
Fig. 5. Balaenoptera physalus. The work against drag correlates with the fill-
ing rate of the buccal cavity. Swimming against drag generates the work
required to stretch the buccal cavity around the volume of prey-laden water.
Here, the reconfiguration of the buccal cavity is represented as a filling rate.
Maxima for filling rate and work against drag occur at the time when the
buccal cavity begins to expand (b; for a,c,d,e, see Fig. 3). Error bars represent
2 standard deviations about the mean
Fig. 6. Balaenoptera physalus. Reconfiguration of the buccal cavity is correlated
with an increase in drag coefficient CD. Shape changes associated with the
reconfiguration of the buccal cavity (represented here as the cumulative volume
engulfed), strongly affects CDor the amount of dynamic pressure that is con-
verted into drag. a–e: see Fig. 3. Error bars represent 2 standard deviations
about the mean
Goldbogen et al.: Fin whale lunge feeding
nitude of this cost may vary according to differences in
morphology, behavior, and mechanical scaling effects.
Engulfment volume
Our mechanical model shows how a 20 m adult fin
whale can engulf, on average, 71 m3of water, a vol-
ume that is larger than that of the whale’s entire body
in its initial state. The reconfiguration of the buccal
cavity that is predicted to accommodate this volume
is well within the mechanical properties demon-
strated by Orton & Brodie (1987). The impressive
engulfment capacity of rorquals is quite obvious from
photographs of lunge feeding near the sea surface.
The magnitude of the engulfed volume has been the
subject of a great deal of speculation, with estimates
based on anecdote (Pivorunas 1979), aerial photo-
graphs (Storro-Patterson 1981), and post mortem
specimens (Lockyer 1981). These authors predicted a
wide range of engulfment volumes, ranging from 10
to 600% of the whales’ initial body volume. Based on
our model, we suggest that the majority of fin whale
lunges result in a volume of water that ranges from
120 to 160% body volume (Fig. 3).
Post mortem observations (Schulte 1916) and experi-
ments (Lambertsen et al. 1995, Brodie 2001) suggest
the temporomandibular joint and associated myoten-
dinous structures act like a spring to store kinetic
energy during mouth opening, which, in turn, could
be used to help power mouth closure (Sanderson &
Wassersug 1993, Lambertsen et al.
1995). Considering the mechanics of
these types of elastic structures (Ahl-
born 2004), the time it takes to open
and close the jaws must be approxi-
mately equal. Our results for gape
angle dynamics show that it takes the
same amount of time for a rorqual to
open and to close its mouth (Fig. 2), a
finding that does not falsify the ‘spring-
loaded’ jaw hypothesis. Arnold et al.
(2005) demonstrated that minke whales
had maximum gape angles of only 40°,
although these data were documented
during non-feeding gulps that ap-
peared to be behavioral displays. How-
ever, minke whales were also observed
to depress the mandibles to approxi-
mately 70° during ‘inter-mandibular
gulps’ (Arnold et al. 2005), a jaw com-
pliance that is comparable to what was
observed here (Fig. 2) as well as in sev-
eral previous studies (Lambertsen et al.
1995, Brodie 2001).
If rorquals are able to control how far the mandibles
are depressed during a lunge, then the magnitude of
the engulfed volume may be under voluntary control
(Arnold et al. 2005). Given the link between drag and
engulfment volume (Figs. 4 to 6), rorquals should then
be able to take smaller gulps at a relatively lower ener-
getic cost. This modal feeding behavior may be advan-
tageous when lunges are directed towards smaller
aggregations of prey. To capture more agile prey, how-
ever, we predict that rorquals will increase maximum
lunge speed rather than limit maximum gape angle. A
higher attack speed coupled with an enlarged mouth
will reduce the detrimental scaling effects of unsteady
locomotion that cause large predators to be much less
maneuverable than their smaller prey (Webb & de Buf-
frenil 1990, Domenici 2001).
Unlike other large continuous ram filter-feeding ver-
tebrates, such as the right whale Eubalaena spp. and
basking shark Cetorhinus maximus, lunge feeding in
rorquals is largely a matter of processing after seizing
parts of large aggregations of krill and copepods or
schools of fish. In this perspective, the raptorial feeding
used by odontocetes to capture individual prey items
may not be functionally different from the feeding
strategy used by rorquals: lunge-feeding mysticetes
are simply pursuing individual superorganisms.
Therefore, large aggregations of prey represent a unit
that may be less maneuverable than its individual
members (Webb & de Buffrenil 1990, Domenici 2001),
thereby increasing the success rate of a predation
event.
297
Table 2. Parameters generated by the mechanical and hydrodynamic model.
The range represents the model output for two standard deviations about the
mean body speed calculated for 50 lunges among 7 individual fin whales
Parameter Symbol Average value Range
Engulfment volume VE71 m360 – 82 m3
Filter rate F2.4 m3s–1 2.0 – 2.7 m3s–1
Drag (initial) Di6 kN 6 – 7 kN
Drag (maximum) Dmax 20 kN 17 – 22 kN
Work against drag (initial) Wi19 kJ 15 – 23 kJ
Work against drag (maximum) Wmax 44 kJ 28 – 58 kJ
Drag coefficient (initial) CDi 0.2 0.2 – 0.3
Drag coefficient (maximum) CDmax 3.2 2.2 – 5.1
Reynolds number for flow past ReF570 480 – 650
Baleen fringes
Reynolds number for flow past ReP4500 3800 – 5200
Baleen plates
Filtering flow speed O
ˇ0.8 m s–1 0.7 – 0.9 m3s–1
Mass krill obtained per lunge KL11 kg 9 – 12 kg
Number of lunges day–1 to match NL83 73 – 100
daily energetic demand (Γ)
Number of foraging dives NF21 18 – 25
required to execute NL
Foraging time required TF3.1 h 2.8 – 3.8 h
to execute NF
Mar Ecol Prog Ser 349: 289–301, 2007
Filter performance
From the time observed between lunges at depth
(Goldbogen et al. 2006), the large engulfment volume
calculated here is apparently filtered at a rapid rate
(Table 2). However, this mass flow rate distributed over
the large filter surface area yielded moderate Refor
fluid flow past the baleen fringes. After passing
through the fringes, water then passes through the
gaps between baleen plates, for which we estimate
high Re. Whether such flow is laminar or turbulent will
ultimately depend on the material properties (i.e.
smoothness, flexural stiffness) of the baleen.
Remarkably, both the flow speed and Refor water
flow past the baleen fringes (0.8 m s–1, 570) are similar
to the values reported for gill rakers of pump suspen-
sion-feeding fishes (0.4 to 0.7 m s–1, 150 to 600; Sander-
son et al. 2001) that employ cross-flow filtration. This
comparison presents the possibility that the baleen
fringes may also operate as a cross-flow filter rather
than a dead-end sieve. This hypothesis is indirectly
supported by the observations of Kot (2005), who re-
ported a rebounding wave within the buccal cavity that
travels largely parallel with the filtering surface. This
mechanism would enhance filter efficiency and help
avoid some of the difficulties of removing prey from
baleen, a problem discussed in detail by Werth (2001).
Lunge feeding to meet an energetic demand
Based on data for fasting fin whales, Brodie (1975)
estimated a daily energetic demand of 996 kg of krill
per day. This prediction is strongly supported by the
mean of 5 other recent models of baleen whale bio-
energetics (Croll et al. 2006), which give a daily prey
biomass requirement of 901 ± 258 kg. For an average
krill density measured at baleen whale foraging sites
(Croll et al. 2005), our model predicts a fin whale can
obtain approximately 11 kg of krill per lunge (Table 2).
By combining these data, we suggest an adult fin
whale can meet its daily energetic demand with
83 lunges distributed over 21 foraging dives. Interest-
ingly, this effort can be met by a foraging time of about
3 h. The foraging effort predicted here, however, is
strongly dependent on the density and depth of prey.
Large rorquals that apparently put on 4% of their body
weight daily during a summer feeding season (Lockyer
1981) would be predicted to forage for approximately
6 h from the model presented here. It seems that lunge
feeding is a key mechanism not just for maintaining a
large body size, but also to develop substantial lipid
stores that are needed for long-term migration and
fasting. For these reasons, we predict a high foraging
efficiency for rorqual lunges despite high drag.
Drag
Our dynamic evaluation of the drag coefficient (CD)
reveals a remarkable increase in its value over the
course of a lunge, by at least an order of magnitude
(Fig. 4). Its initial value is comparable to those of well-
streamlined bodies, but quickly becomes far greater
than even the values reported for hollow-half hemi-
spheres concave to steady flow (see Vogel 1994). This
time course of CDis similar to values determined for an
inflating circular parachute, which increases from 0.09
to 4.12 (Dneprov 1993, Peterson et al. 1996). The CD
values calculated here for a decelerating fin whale are
also consistent with those determined for circular discs
(CD> 5) when exposed to unsteady flows (Higuchi et
al. 1996). Thus, it appears that lunge-feeding fin
whales undergo a rapid transformation from a well-
streamlined shape to one that is extremely disposed to
drag. This shape change is advantageous because
drag arising from dynamic pressure is absolutely
required to expand the buccal cavity (Orton & Brodie
1987). The analogy between inflating parachutes and
lunge-feeding whales is appropriate since the purpose
in each scenario is to produce drag.
As the buccal cavity fills, separation of flow may
occur along the lateral margins of the mandibles, but
probably more so along the rostrum and exposed
baleen. Early separation of flow will create large pres-
sure differences along the body and increase drag on
the body rather than the exposed buccal cavity. Thus,
we predict that the rorqual mandible and surrounding
tissues are well streamlined so that during a lunge, the
mandibles themselves do not experience significant
drag. Instead, dynamic pressure is increased within
the area encompassed by the mandibles, thereby
enhancing expansion of the buccal cavity. Preliminary
measurements support a hydrodynamic design of the
rorqual mandible (see also cross-sections by Pivorunas
1977, Lambertsen 1983), and this is now the focus of a
current study already underway (Goldbogen & Pyen-
son unpubl. data).
Ecology and evolution
Despite the high energetic cost of lunge feeding in
fin whales, this specialized vertebrate feeding strat-
egy has limited neither the ecological nor the evolu-
tionary diversification of lunge-feeding baleen whales
(Fig. 7). Thus, the selective advantages of lunge feed-
ing, namely a large engulfment capacity that may
render lunge feeding to be quite efficient overall,
seem to outweigh the energetic cost of high drag. All
members of the Balaenopteridae are lunge feeders,
and, in terms of ecological specialization, extant bal-
298
Goldbogen et al.: Fin whale lunge feeding
aenopterid species range in discrete size categories
from 7 m minke whales to 30 m blue whales, with
concomitant prey and behavioral specializations that
further partition modern balaenopterid feeding ecol-
ogy (Mitchell 1974, Lockyer 1981, Tershy 1992).
Furthermore, rorquals were major consumers of
worldwide oceanic productivity before the advent of
mechanized whaling, and, as such, they played a fun-
damental role in structuring ocean ecosystems (Croll
et al. 2006).
Lunge feeding in balaenopterids contrasts signifi-
cantly with the continuous ram feeding (Sanderson &
Wassersug 1993, Werth 2000) exhibited by right and
bowhead whales (Balaenidae), which are the sister
group to Balaenopteroidea (Balaenopteridae + gray
whales; sensu Deméré et al. 2005). Rorquals are
among the most speciose groups of living cetaceans,
whereas balaenids comprise only a few species; a dif-
ference that is also observed in the generic diversity
of these 2 groups throughout their evolutionary his-
tory (Lindberg & Pyenson 2006). Preliminary recon-
structions of body size in extinct balaenopteroids
indicate that, ancestrally, this group of baleen whales
did not exhibit the larger size categories of their
extant relatives (Pyenson & Sponberg 2007), and the
same situation appears to be true for the balaenid lin-
eage as well (Bisconti 2005). These data, together
with the apparent monophyly of Balaeopteroidea
(Deméré et al. 2005), provide tentative support for an
evolutionary scenario advanced by Lambertsen et al.
(1995), which frames lunge feeding as a putative key
innovation that enhanced a pre-existing suite of en-
gulfment-assisting morphological characters (Kimura
2002, Deméré et al. 2005). Moreover, the present
diversity of living balaenopterids (in terms of both
prey preferences and body size range; Lindberg &
Pyenson 2006), sister group comparisons, and ances-
tral body size reconstruction all suggest that the
advent of lunge feeding provided an ecological
advantage that promoted large body size in the bal-
aenopterid lineage, eventually providing the opportu-
nity for the evolution of some of the largest organisms
that have ever existed. However, these hypotheses
cannot be tested until (1) further comparative work
identifies clear evolutionary transformations in the
cranial and mandibular character complexes (e.g.
temporomandibular joint), (2) phylogenetic analysis
resolves the placement of key fossil taxa (Deméré et
al. 2005), and (3) the pattern of body size evolution in
mysticetes becomes clearly elucidated.
Acknowledgements. Funding for tag operations was pro-
vided by the US Navy. We thank B. Burgess for the develop-
ment of the Bioacoustic Probe. We also thank the Cascadia
Research Collective, E. Oleson, and M. McDonald for their
role in tagging fin whales. We thank 3 anonymous reviewers
for their thorough comments that enhanced the content and
quality of this paper. Funding for the development of this
physical model and manuscript was provided by NSERC to
R.E.S. Support for this work was also provided by a travel
grant from UCMP Remington Kellogg Fund and NSF GRF to
N.D.P. We especially thank J. Potvin for critical feedback and
advice regarding the unsteady evaluation of drag. Members
of the C4NT in San Diego, including R. Burgundy, B. Fantana
and B. Tamland, provided valuable motivation during the
course of this study. We thank C. Conroy, S. Davenport,
K. Fahy, D. Janiger and C. Potter for access to specimens. We
also thank B. Ahlborn, L. Barnes, P. Brodie, J. Calambokidis,
F. Fish, J. Gosline, J. Hildebrand, D. Janiger, D. Lindberg,
E. Mitchell, J. Meir, G. Szulgit, S. Vogel, and M. Wedel for
their comments, assistance and encouragement. This paper
is UCMP Contribution No. 1941.
LITERATURE CITED
Acevedo-Gutierrez A, Croll DA, Tershy BR (2002) High feed-
ing costs limit dive time in the largest whales. J Exp Biol
205:1747–1753
Ahlborn BK (2004) Zoological physics, 2nd edn. Springer-Ver-
lag, Berlin
Arnold PW, Birtles RA, Sobtzick S, Matthews M, Dunstan A
(2005) Gulping behaviour in rorqual whales: underwater
observations and functional interpretation. Mem Queensl
Mus 51:309– 332
Bisconti M (2005) Skull morphology and phylogenetic rela-
tionships of a new dimunitive balaenid from the Lower
Pliocene of Belgium. Palaeontology 48:793– 816. doi:
10.1111/j.1475– 4983.2005.00488.x
Blix AS, Folkow LP (1995) Daily energy expenditure in free
living minke whales. Acta Physiol Scand 153:61–66
299
Fig. 7. A cladogram showing the relationships among living
baleen whales lineages, using the topology presented by
Sasaki et al. (2005). Balaenoptera physalus, or the fin whale,
is the focus of this study, and it is highlighted by a gray box.
Note the poor resolution (polytomy) within Balaenopteroidea
(sensu Deméré et al. 2005) and the potential non-monophyly
of Balaenopteridae and Balaenoptera. B. brydei is also likely
polytypic (Sasaki et al. 2006)
Mar Ecol Prog Ser 349: 289–301, 2007
Bose N, Lien J (1989) Propulsion of a fin whale (Balaenoptera
physalus): why the fin whale is a fast swimmer. Proc R Soc
Lond B 237:175–200
Brodie PF (1975) Cetacean energetics, an overview of
intraspecific size variation. Ecology 56:152–161
Brodie PF (1993) Noise generated by the jaw actions of feed-
ing fin whales. Can J Zool 71:2546–2550
Brodie PF (2001) Feeding mechanics of rorquals (Bal-
aenoptera sp.). In: Mazin JM, de Buffrenil V (eds) Sec-
ondary adaptation of tetrapods to life in water. Verlag Dr.
Friedrich Pfeil, München, p 345– 352
Butler PJ, Jones DR (1982) The comparative physiology of
diving in vertebrates. Adv Comp Physiol Biochem 8:
179– 364
Croll DA, Acevedo-Gutierrez A, Tershy BR, Urban-Ramirez J
(2001) The diving behavior of blue and fin whales: Is dive
duration shorter than expected based on oxygen stores?
Comp Biochem Physiol A 129:797–809
Croll DA, Marinovic B, Benson S, Chavez FP, Black N, Ternullo
R, Tershy BR (2005) From wind to whales: trophic links in a
coastal upwelling system. Mar Ecol Prog Ser 289:117–130
Croll DA, Kudela R, Tershy BR (2006) Ecosystem impact of the
decline of large whales in the North Pacific. In: Estes JA,
et al (eds) Whales, whaling and ocean ecosystems. Univer-
sity of California Press, Berkeley, p 202–214
Deméré TA, Berta A, McGowen MR (2005) The taxonomic
and evolutionary history of fossil and modern bal-
aenopteroid mysticetes. J Mamm Evol 12:99–143. doi:
10.1007/s10914– 005–6944 3
Dneprov IV (1993) Computation of aeroelastic characteristics
and stress-strained state of parachutes. In: Proceedings of
the 12th RAeS/AIAA Aerodyn Decelerator Systems Tech-
nol Conf and Seminar. AIAA, London, p 93–1237
Domenici P (2001) Scaling the locomotor performance in
predator–prey interactions: from fish to killer whales.
Comp Biochem Physiol A 131:169–182
Folkens P (2003) National Audubon Society guide to marine
mammals of the world. Chanticleer Press, New York,
p 230–231
Goldbogen JA, Calambokidis J, Shadwick RE, Oleson EM,
McDonald MA, Hildebrand JA (2006) Kinematics of forag-
ing dives and lunge-feeding in fin whales. J Exp Biol 209:
1231–1244
Halsey LG, Butler PJ, Blackburn TM (2006) A phylogenetic
analysis of the allometry of diving. Am Nat 167:276–287
Higuchi H, Balligand H, Strickland JH (1996) Numerical and
experimental investigations of the flow over a disk under-
going unsteady motion. J Fluids Struct 10:705–719
Iversen HW, Balent R (1951) A correlating modulus for fluid
resistance in accelerated motions. J Appl Phys 22:324–328
Kawamura A (1980) A review of food of balaenopterid
whales. Sci Rep Whales Res Inst 32:155–197
Kimura T (2002) Feeding strategy of an Early Miocene
cetothere from the Toyama and Akeyo Formations, central
Japan. Paleontol Res 6:2
Kot BW (2005) Rorqual whale surface-feeding strategies: bio-
mechanical aspects of feeding anatomy and exploitation
of prey aggregations along tidal fronts. MSc thesis, Uni-
versity of California, Los Angeles
Krutzikowsky GK, Mate BR (2000) Dive and surface charac-
teristics of bowhead whales (Balaena mysticetus) in the
Beaufort and Chukchi Seas. Can J Zool 78:1182–1198
Lambertsen RH (1983) Internal mechanism of rorqual feed-
ing. J Mammal 64:76– 88
Lambertsen R, Ulrich N, Straley J (1995) Frontomandibular
stay of balaenopteridae a mechanism for momentum
recapture during feeding. J Mamm 76:877–899
Lindberg DR, Pyenson ND (2006) Evolutionary patterns in
Cetacea: fishing up prey size through deep time. In: Estes
JA DeMaster DP, Doak DF, Williams TM, Brownell RL Jr
(eds) Whales, whaling and ocean ecosystems. University
of California Press, Berkeley, p 67–81
Lockyer C (1976) Body weights of some species of large
whales. J Cons Int Explor Mer 36:259–273
Lockyer C (1981) Growth and energy budgets of large baleen
whales from the southern hemisphere. In: Mammals in the
seas, Vol. III. General papers and large Cetaceans. FAO
Fish Ser 5:379– 487
Lockyer C, Waters T (1986) Weights and anatomical measure-
ments of Northeastern Atlantic fin (Balaneoptera phy-
salus, Linnaeus) and sei (B. borealis, Lesson) whales. Mar
Mamm Sci 2:169–185
Mitchell ED (1974) Trophic relationships and competition for
food in Northwest Atlantic whales. In: Proceedings of the
Canadian Socitey of Zoology Annual Meeting. Canadian
Society of Zoology, Fredericton, p 123–133
Nerini M (1984) A review of gray whale feeding ecology. In:
Jones ML, Swartz SL, Leatherwood S (eds) The gray
whale, Eschrichtius robustus. Academic Press, New York,
p 423– 450
Orton LS, Brodie PF (1987) Engulfing mechanics of fin
whales. Can J Zool 65:2898–2907
Panigada S, Zanardelli M, Canese S, Jahoda M (1999) How
deep can baleen whales dive? Mar Ecol Prog Ser 187:
309– 311
Peterson CW, Strickland JH, Higuchi H (1996) The fluid
dynamics of parachute inflation. Annu Rev Fluid Mech 28:
361–387
Pivorunas A (1976) A mathematical consideration of the func-
tion of baleen plates and their fringes. Sci Rep Whales Res
Inst 28:37–55
Pivorunas A (1977) Fibrocartilage skeleton and related struc-
tures of ventral pouch of balaenopterid whales. J Morphol
151:299– 313
Pivorunas A (1979) The feeding mechanisms of baleen
whales. Am Sci 67:432– 440
Potvin J, Peek G, Brocato B (2003) New model of decelerating
bluff body drag. J Aircraft 40:370–377
Pyenson ND, Sponberg S (2007) Reconstructing body size in
extinct crown Cetacea using allometric scaling, phylo-
genetic comparative methods, and tests from the fossil
record. In: Warren A (ed) Conf on Australiasian Verte-
brate Evolution, Palaeontology and Systematics 2007.
Geol Soc Aust Abst 85:51–52
Sanderson SL, Wassersug R (1993) Convergent and alterna-
tive designs for vertebrate suspension feeding. In: Hanken
J, Hall BK (eds) The skull: functional and evolutionary
mechanisms. University of Chicago Press, p 37–112
Sanderson SL, Cheer AY, Goodrich JS, Graziano JD, Callan
WT (2001) Crossflow filtration in suspension-feeding
fishes. Nature 412:439–441
Sasaki T, Nikaido M, Hamilton H, Goto M and 6 others (2005)
Mitochondrial phylogenetics and evolution of mysticete
whales. Syst Biol 54:77–90
Sasaki T, Nikaido M, Wada S, Yamada TK, Cao Y, Hasegawa
M, Okada N (2006) Balaenoptera omurai is a newly dis-
covered baleen whale that represents an ancient evolu-
tionary lineage. Mol Phylogenet Evol 41:40–52
Schulte HVW (1916) Anatomy of a foetus. Balaenoptera bore-
alis. Mem Am Mus Nat Hist 6:389– 502
Stockin KA, Fairbairns RS, Parsons ECM, Sims DW (2001)
Effects of diel and seasonal cycles on the dive duration of
the minke whale (Balaenoptera acutorostrata). J Mar Biol
Assoc UK 81:189–190
300
Goldbogen et al.: Fin whale lunge feeding
Storro-Patterson R (1981) The great gulping blue whales.
Oceans 14:16–17
Tershy B (1992) Body size, diet, habitat use, and social behav-
ior of Balaenoptera whales in the Gulf of California.
J Mamm 73:477–486
True FW (1904) Whalebone whales of the western North
Atlantic. Smithson Contrib Knowledge 33:1–332
Vogel S (1994) Life in moving fluids: the physical biology of
flow, 2nd edn. Princeton University Press, Princeton, NJ
Webb PW, de Buffrenil V (1990) Locomotion in the biology
of large aquatic vertebrates. Trans Am Fish Soc 119:
629– 641
Werth AJ (2000) Feeding in marine mammals. In: Schwenk K
(ed) Feeding: form, function and evolution in tetrapod ver-
tebrates.Academic Press, New York, p 475– 514
Werth AJ (2001) How do mysticetes remove prey trapped in
baleen? Bull Mus Comp Zool 156:189–203
Williams TM (1999) The evolution of cost efficient swimming
in marine mammals: limits to energetic optimization. Phi-
los Trans R Soc Lond B 354:193–201
301
Editorial responsibility: Rory Wilson (Contributing Editor),
Swansea, UK
Submitted: March 27, 2007; Accepted: May 21, 2007
Proofs received from author(s): October 16, 2007
... Bulk feeding on small aggregating prey enables access to large amounts of energy at lower trophic levels, which is required for rorquals to maintain large body sizes (Goldbogen and Madsen 2018 ;Goldbogen et al. 2019 ). Lunge feeding has been described as the largest biomechanical event on the planet (Brodie 1993 ) and involves a rorqual accelerating toward a patch of prey and opening its mouth to engulf a volume of prey-laden water that can be larger than its own body volume (Goldbogen et al. 2007(Goldbogen et al. , 2010. This process is repeated successively during a foraging dive, with each lunge averaging 16 s and the interval between lunges averaging 30 s in fin whales (Goldbogen et al. 2006(Goldbogen et al. , 2007. ...
... Lunge feeding has been described as the largest biomechanical event on the planet (Brodie 1993 ) and involves a rorqual accelerating toward a patch of prey and opening its mouth to engulf a volume of prey-laden water that can be larger than its own body volume (Goldbogen et al. 2007(Goldbogen et al. , 2010. This process is repeated successively during a foraging dive, with each lunge averaging 16 s and the interval between lunges averaging 30 s in fin whales (Goldbogen et al. 2006(Goldbogen et al. , 2007. During the inter-lunge interval, the engulfed water is filtere d out through the baleen plates to concentrate the prey in the oral cavity while the oral plug remains in position, followed by swallowing of the prey when the oral plug is retracted )-a process that must be completed before the whale can open its mouth for the next lunge. ...
... Mathematical models of fin whale buccal cavity and ventral groove blubber (VGB) inflation have produced estimates of the amount of water engulfed per lunge (Goldbogen et al. 2006(Goldbogen et al. , 2007Potvin et al. 2009 ); however, the amount of prey captured in a lunge varies depending on prey density, patch size, and distribution in the environment . Additionally, measurements of krill density span across orders of magnitude depending on the time of sampling and the method used to sample (Goldbogen et al. 2011 ). ...
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Synopsis Lunge feeding rorqual whales feed by engulfing a volume of prey laden water that can be as large as their own body. Multiple feeding lunges occur during a single foraging dive and the time between each lunge can be as short as 30 s (Goldbogen et al. 2013). During this short inter-lunge time, water is filtered out through baleen to concentrate prey in the oral cavity, and then the prey is swallowed prior to initiating the next lunge. Prey density in the ocean varies greatly, and despite the potential of swallowing a massive volume of concentrated prey as a slurry, the esophagus of rorqual whales has been anecdotally described as unexpectedly narrow with a limited capacity to expand. How rorquals swallow large quantities of food down a narrow esophagus during a limited inter-lunge time remains unknown. Here, we show that the small diameter muscular esophagus in the fin whale is optimized to transport a slurry of food to the stomach. A thick wall of striated muscle occurs at the pharyngeal end of the esophagus which, together with the muscular wall of the pharynx, may generate a pressure head for transporting the food down the esophagus to the stomach as a continuous stream rather than separating the food into individual boluses swallowed separately. This simple model is consistent with estimates of prey density and stomach capacity. Rorquals may be the only animals that capture a volume of food too large to swallow as a single intact bolus without oral processing, so the adaptations of the esophagus are imperative for transporting these large volumes of concentrated food to the stomach during a time-limited dive involving multiple lunges.
... The whale then closes its mouth, trapping the prey inside. Finally, the buccal cavity deflates as the water is expelled through the baleen plates, leaving a bolus of prey, which is then swallowed (Goldbogen et al. 2007). ...
... Speed and depth data were then smoothed using a Butterworth lowpass filter (zero-phase, cf = 0.4 Hz). Feeding lunges were identified in the tag data based on the rapid accelerations and abrupt decelerations that characterize foraging in other rorqual species (Goldbogen et al. 2007). ...
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... The density of krill patches varies largely with depth, with high-density aggregations at depth during the day and low-density aggregations near the sea surface at night (Hewitt & Demer 2000). Moreover, foraging dive time is limited in baleen whales due to the high energetic costs of drag associated with their lunging technique to capture prey (Goldbogen et al. 2007). ...
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Over recent decades, the feeding strategies of the blue whale (Balaenoptera musculus) in the northern Chilean Patagonia have been studied mainly through visual observation and anatomical dissection, with limited direct behavioral analyses and measurements of prey distribution due to the difficulty of sampling. Here, we investigated the foraging ecology of this species during six annual research cruises (2014–2019) in the northern Chilean Patagonia, an important feeding and nursery area. We deployed 28 sound and movement recording tags (DTAGs), attached by suction cups, to measure fine-scale behaviors of this species. In addition, from 2016 to 2019, prey density and distribution were simultaneously recorded with tag data utilizing a scientific echosounder. A total of 949 foraging dives and 3,183 feeding events were detected from movement sensors throughout more than 190 hr of data, during both day and nighttime. Blue whales exhibited both shallow and deep foraging events utilizing different strategies in response to changing conditions of prey depth and density, with foraging dives recorded continuously for the whole duration of the deployments. Whales showed a higher feeding rate at night as they foraged on shallow and dispersed krill, but they exhibited a higher rate of foraging events per dive during the day, as they foraged on deep and dense krill patches. The whales used less energetically costly maneuvers when foraging near the surface, with lower values of pitch and speed. Both strategies are consistent with optimal foraging theory, as the whales minimizing energetic costs associated with feeding while simultaneously maximizing energy intake. These results provide valuable insights into the behavioral and foraging ecology of blue whales to promote specific conservation plans in the northern Chilean Patagonia.
... Sanderson et al. (2001) identified this unexpected hydrodynamic configuration as crossflow filtration. The crossflow configuration has also been proposed for balaenopterid (Goldbogen et al., 2007;Potvin et al., 2009) and balaenid whales (Werth and Potvin, 2016). ...
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... Sei whales, B. borealis, display a morphotype somewhat intermediate between balaenids and other balaenopterids (Werth et al., 2018a), and are known to switch facultatively between lunge feeding and balaenid-style skim feeding depending on targeted prey (Segre et al., 2021). Scalable parameters of rorqual lunge feeding vary somewhat by species and size yet display remarkable ecological/behavioral and morphological/physiological consistency in traits ranging from gape angle and duration to timing of water filtration and expulsion (Goldbogen et al., 2006, Goldbogen et al., 2007, Goldbogen et al., 2011Goldbogen et al., 2012a, Goldbogen et al., 2012bPotvin et al., 2009, Potvin et al., 2012Goldbogen et al., 2015;Cade et al., 2016;Kahane-Rapport et al., 2020;Potvin et al., 2020, Potvin et al., 2021. Generally, all engulfed water is expelled from the expanded oral and throat pouch within about 20 s (Goldbogen et al., 2017b). ...
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Recent findings have greatly improved our understanding of mysticete oral filtration, and have upended the traditional view of baleen filtration as a simple process. Flow tank experiments, telemetric tag deployment on whales, and other lab and field methods continue to yield new data and ideas. These suggest that several mechanisms arose from ecological, morphological, and biomechanical adaptations facilitating the evolution of extreme body size in Mysticeti. Multiple lines of evidence strongly support a characterization of baleen filtration as a conceptually dynamic process, varying according to diverse intraoral locations and times of the filtration process, and to other prevailing conditions. We review and highlight these lines of evidence as follows. First, baleen appears to work as a complex metafilter comprising multiple components with differing properties. These include major and minor plates and eroded fringes (AKA bristles or hairs), as well as whole baleen racks. Second, it is clear that different whale species rely on varied ecological filtration modes ranging from slow skimming to high-speed lunging, with other possibilities in between. Third, baleen filtration appears to be a highly dynamic and flow-dependent process, with baleen porosity not only varying across sites within a single rack, but also by flow direction, speed, and volume. Fourth, findings indicate that baleen (particularly of balaenid whales and possibly other species) generally functions not as a simple throughput sieve, but instead likely uses cross-flow or other tangential filtration, as in many biological systems. Fifth, evidence reveals that the time course of baleen filtration, including rate of filter filling and clearing, appears to be more complex than formerly envisioned. Flow direction, and possibly plate and fringe orientation, appears to change during different stages of ram filtration and water expulsion. Sixth, baleen’s flexibility and related biomechanical properties varies by location within the whole filter (=rack), leading to varying filtration conditions and outcomes. Seventh, the means of clearing/cleaning the baleen filter, whether by hydraulic, hydrodynamic, or mechanical methods, appears to vary by species and feeding type, notably intermittent lunging versus continuous skimming. Together, these and other findings of the past two decades have greatly elucidated processes of baleen filtration, and heightened the need for further research. Many aspects of baleen filtration may pertain to other biological filters; designers can apply several aspects to artificial filtration, both to better understand natural systems and to design and manufacture more effective synthetic filters. Understanding common versus unique features of varied filtration phenomena, both biological and artificial, will continue to aid scientific and technical understanding, enable fruitful interdisciplinary partnerships, and yield new filter designs.
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Coronodon includes species of basal toothed mysticetes that were initially interpreted as engaging in raptorial feeding and dental filtration. Here, the feeding of this extinct genus is revisited based on recently described specimens and species. Associations between tooth position and types of dental wear were tested, and evidence for feeding behaviors was tabulated using scores from 14 craniodental characters, each mapped onto five alternate phylogenetic hypotheses. Individual character states were interpreted as being supportive, neutral, or contradictory evidence to raptorial feeding, suction feeding, baleen filtration, or dental filtration. Wear in Coronodon was found to be significantly more concentrated on mesial teeth, mesial cusps, higher cusps, and upper teeth. Upper teeth also had mesial cusps more worn than distal cusps, inconsistent with predictions of the dental filtration hypothesis. Wear in notches was correlated with wear on neighboring cusps, and side wear was concentrated on occlusal sides, suggesting both were caused by raptorial feeding. These observations raise the possibility that raptorial feeding was the primary, and maybe even the only, mode of feeding for Coronodon. The feeding scores of reconstructed ancestors leading to crown mysticetes typically display a stepwise decrease in raptorial feeding, a stepwise increase in baleen filtration, and, occasionally, an intermediate but weakly supported stage of dental filtration. For most toothed mysticetes, there is little evidence for or against suction feeding. The method we have developed for studying the origin of baleen can be expanded and allows for multiple hypotheses to be tested without undue emphasis on any particular taxon or set of characters.
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