J-STAGE Advance published date: March 3, 2021

FETAL DEVELOPMENT IN TAIL FLUKES OF THE ANTARCTIC MINKE WHALEFETAL DEVELOPMENT IN TAIL FLUKES OF
THE ANTARCTIC MINKE WHALE
Yujin KIM1*, Futaba NISHIMURA1, Takeharu BANDO2, Yoshihiro FUJISE2,Gen NAKAMURA1, Hiroto MURASE1 and Hidehiro KATO1, 2
1

Laboratory of Cetacean Biology, Tokyo University of Marine Science and Technology,
4–5–7 Konan, Minato-ku, Tokyo 108–8477, Japan
2
Institute of Cetacean Research, 4–5 Toyomi-cho, Chuo-ku, Tokyo 104–0055, Japan*Corresponding author: 0101leonxd@gmail.com

Abstract
Tail ﬂukes of the Antarctic minke whale fetuses were studied to expand the available knowledge on fetal development, which is relatively understudied, as previous studies are qualitativein nature. Seven measurement points on the tail ﬂukes of 122 fetuses (after conception 12.9
to 259.5 days) were recorded. We quantitatively deﬁned the developmental stages based on
the measurements. Tail ﬂukes formed after an estimated fetal age of 57.8 days (9.4 cm) andretained almost the same shape as postnatal at 124.6 days (47.3 cm). The results also revealed
that the growth rates diﬀered at each measurement point and each developmental stage.
Key words:

Antarctic minke whale, Balaenopteridae, embryology, fetus, ﬂuke, ontogeny.

Several descriptive studies on the morphological changes in tail ﬂukes (hereafter, ﬂukes) during
intrauterine development were conducted on mysticetes (Ogawa, 1953; Ohsumi, 1960; Roston etal., 2013) and odontocetes (Ogawa, 1953; Nishiwaki et al., 1963; Amano and Miyazaki, 1993; Štěrba
et al., 2000; Thewissen, 2018). However, quantitative studies—measurements and statistical analysis—on the developmental changes of ﬂukes which is one of the most attractive and drastic changes
are expected during the intrauterine period, are limited as obtaining a suﬃcient number of fetal samples for such an analysis is diﬃcult.
This paper provides such quantitative information as above on the development of fetal ﬂukes incetaceans using the Antarctic minke whales (Balaenoptera bonaerensis) and measurements obtained
from the New Scientiﬁc Whale Research Program in the Antarctic Ocean (NEWREP-A) operation in
2017/18 under the special permit issued by Government of Japan in accordance with the International
Convention for Regulation of Whaling (ICRW) (Bando et al., 2018). Samples were collected from the
Paciﬁc sector of the Antarctic area bounded by 170°W, 120°W, 60°S, and sea ice edge (or coastline),
which corresponds to Area VI as deﬁned by the International Whaling Commission (IWC).
NEWREP-A commenced in the austral summer of 2017/18 and the seasons after with the ﬁrst author, Kim Y. as well as Bando T. and Nishimura F., on board the research base R/V Nisshin Maru inthat year (8,030 GT). Through the sampling exercises, 122 fetuses from 122 pregnant females were
examined by Kim alongside Bando and Nishimura.
Measurements, including the body length and ﬂuke morphometrics with ﬁve measurement points,
namely, total span (TS), maximum span (MS), depth of ﬂukes (DF), anterior length (AL), and posterior
length (PL) as deﬁned in Fig. 1, derived from Ohsumi (1960) for ﬁn whales (B. physalus) and Amanoand Miyazaki (1993) for Dall’s porpoises (Phocoenoides dalli), were made during the ﬁeld survey. TS
and MS were treated as the same for fetuses with less than 47.3 cm in body length because the fetal
ﬂukes have indistinguishable tips during the initial developmental stages as their skin lobes are rounded. The body length was measured parallel to the body axis, from the tip of the upper jaw to the notchof the ﬂukes to the nearest 0.1 cm. Body lengths of small fetuses with bent heads and tails were meaCetacean Popul. Stud. (CPOPS), Short noteVol. 3, 2021, 231–238

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Fig. 1. Measurement points of ﬂukes from the Antarctic minke whale fetuses: total span (TS), from left tip toright tip; maximum span (MS), from left ridge to right ridge; depth of ﬂukes (DF), from anterior insertion, themost anterior point of skin lobes which was visually determined by the ﬁrst author, to notch; anterior length(AL), from anterior insertion to tip; posterior length (PL), from notch to tip; distance to notch (DN), from theleft anterior insertion and right anterior insertion lines to the notch; and distance to total span (DT), from left
anterior insertion and right anterior insertion lines to TS.

Fig. 2. Developmental stages of the ﬂukes as the Antarctic minke whale fetuses develop: Stage (0), tail shape;
Stage (1), diamond shape; Stage (2), triangle shape; Stage (3), boomerang shape.

sured along the curved body axis. These measurement points were measured to three decimal places
along a straight line from point to point using 30 or 40 cm vernier calipers. Two additional measurement points, namely, distance to notch (DN) and distance to total span (DT), were measured. Because
the ﬂukes’ tips are curved ventrally and both points could not be measured accurately in the ﬁeld, bothmeasurement points were measured to three decimal places using digital photographs of ﬂukes in thelaboratory using the ImageJ software developed by Schneider et al. (2012). Fetal age (number of days
after conception) was estimated from the body length of the Antarctic minke whale using methods
devised by Kato and Miyashita (1991) and seconded by Bando (2017) (see Appendix for the details).
The developmental stages of the fetal ﬂukes were categorized based on Ohsumi (1960) and wereconventionally deﬁned as follows (Fig. 2): Stage (0), tail shape, with a completely tail-like shape withno skin lobes on both sides; Stage (1), diamond shape, when skin lobes form on both sides and ﬂukes
have a diamond-like shape (DT is less than or equal to half of DN); Stage (2), triangle shape, when
ﬂukes become triangular in shape (DT is more than half of DN); and Stage (3), boomerang shape,
when both of the ﬂukes’ tips are pointed and the ﬂukes take a boomerang-like shape (DT is more than
DN). The typical shapes of the Antarctic minke whale ﬂukes during their developmental stages [(0)–(3)] are exempliﬁed as in Fig. 3. We also incorporated the allometric equation (Huxley, 1950). Growth
pattern analyses were evaluated using t-test. Mean values of the ratios of each measurement point to232

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FETAL DEVELOPMENT IN TAIL FLUKES OF THE ANTARCTIC MINKE WHALE

Fig. 3. Photographs of the ﬂukes of the Antarctic minke whale fetuses at each developmental stage. Stage (0),tail shape (4.3 cm, 26.4 days, sex unknown); Stage (1), diamond shape (17.1 cm, 94.4 days, male); Stage (2),triangle shape (34.5 cm, 112.2 days, female); and Stage (3), boomerang shape (53.1 cm, 130.1 days, female).
Black scale bar indicates 1.0 cm, respectively.

the body length at each developmental stage were evaluated using Mann–Whitney U test. Signiﬁcantlevels of both statistical tests were set at 0.05.
The MS/DF and AL/PL ratios indicate the ﬂukes’ aspect and diagonal ratios, respectively. These ratios increased as fetuses develop with the following results (Fig. 4): Stage (1), the MS/DF and AL/PL
ratios increased from 1.0 to 1.4 and from 0.4 to 0.9, respectively; Stage (2), MS/DF increased from
1.7 to 2.9, and AL/PL increased from 0.8 to 1.3; and Stage (3), MS/DF leveled and increased from 2.2
to 3.2, and AL/PL increased from 1.2 to 1.7. At the beginning of Stage (1), MS and DF were almost
the same. However, MS became larger than DF as the fetal ﬂukes developed and elongated along thetransverse axis direction. Meanwhile, at this stage, AL was less than half of PL. This changed late inStage (2) when AL became larger than PL. This means that the anterior edge of ﬂukes grows fasterthan their posterior part.
The result of this study showed that fetal age which corresponded to the developmental stages were
12.9–41.8 days in Stage (0), 57.8–96.0 days in Stage (1), 99.0–118.0 days in Stage (2), and 124.6–
259.5 days in Stage (3) (Table 1). The ﬂukes started developing skin lobes 57.8 days after conception.
The growth patterns of each measurement point to body length are shown in Table 2. In Stage (1),four measurement points showed positive growth patterns relative to the body length. These were TS,
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Fig. 4. The relationship between two ratios of fetal ﬂukes (y axis) and estimated fetal age (x axis) at developmental stages of the Antarctic minke whale. The aspect ratio of the ﬂukes, MS/DF (a), and the diagonal ratioof the outer edges, AL/PL (b). The dotted lines indicate the starting point of each developmental stage of fetal
ﬂukes, from the left to the right: (0), (1), (2), and (3). Stage (0), tail shape; Stage (1), diamond shape; Stage(2), triangle shape; and Stage (3), boomerang shape.
Table 1. The body length and estimated fetal age of the Antarctic minke whale at each developmental stage offetal ﬂukes.
Developmental
stage

N

(0)
(1)
(2)
(3)

3
9
14
96

Body length (cm)

Estimated fetal age (days)

Range

Mean (SD)

Range

Mean (SD)

2.1–6.8
9.4–18.6
21.5–40.5
47.3–203.0

4.4 (2.4)
14.5 (3.0)
33.1 (5.8)
105.1 (35.3)

12.9–41.8
57.8–96.0
99.0–118.0
124.6–259.5

27.0 (14.5)
84.7 (13.3)
110.8 (5.8)
176.6 (30.8)

Stage (0), tail shape; Stage (1), diamond shape; Stage (2), triangle shape; Stage (3), boomerang shape.

MS, AL, and PL (P<0.01). Isometric growth patterns were found in the other three points—DF, DN,
and DT (P>0.05). Positive growth patterns were observed in TS, MS, AL, PL, and DT in Stage (2)(P<0.05), while DF and DN showed isometric growth patterns to body length (P>0.05). In Stage(3), AL, PL, and DT showed positive growth patterns (P<0.01), and isometric growth patterns were
produced at MS, DF, and DN (P>0.05). Negative growth pattern to body length were observed at
TS (P<0.05). In all developmental stages, positive patterns were observed at AL and PL, while DF
and DN showed isometric patterns. As the ﬂukes developed from Stage (2) to (3), the growth patternsof TS and MS changed. In Stage (2), the growth patterns to body length of both measurement points
were positive, but in Stage (3), those two measurement points were diﬀerent. In Stage (3), a negative
growth pattern was observed at TS, and an isometric growth pattern was observed at MS. The growth
pattern of the DT changed from isometric in Stage (1) to positive in Stage (2).
The changes in ratios of each measurement point of the fetal ﬂukes relative to their body length ateach developmental stage are as follows (Table 3, Fig. 5). Each ratio was compared using the average values, and the standard deviations were shown with the average values. TS and MS ratios were
11.1±4.0% in Stage (1) and increased to 22.4±2.6% in Stage (2) (P<0.01). In Stage (3), while TS isconstant at 22.0±2.5% (P>0.05), MS increased to 24.3±1.9% (P<0.01). The DF ratio ranged from
9.7±0.6% to 10.8±1.0% for Stage (1) and (2) (P>0.05). In Stage (3), DF decreased to 9.2±0.5%(P<0.01). The AL and PL ratios increased with the developmental stages. AL increased from5.8±2.1% to 11.7±1.9% when the developmental stage became from Stage (1) to Stage (2) (P<0.01).

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Table 2. The growth patterns of fetal ﬂukes at developmental stages of the Antarctic minke whale.
Developmental
stage

Measurement
point

N

α1

ln β 1

Growthpattern2

r2

P-value

(1)

TS
MS
DF
AL
PL
DN
DT

7
7
4
6
6
7
7

2.605
2.605
0.883
2.341
1.423
0.787
0.937

0.001
0.001
0.149
0.002
0.028
0.178
0.049

Positive
Positive
Isometric
Positive
Positive
Isometric
Isometric

0.980
0.980
0.319
0.934
0.995
0.902
0.778

**
**
n.s.
**
**
n.s.
n.s.

(2)

TS
MS
DF
AL
PL
DN
DT

14
14
14
14
14
13
14

1.544
1.544
0.940
1.737
1.366
1.068
1.970

0.033
0.033
0.120
0.009
0.032
0.079
0.003

Positive
Positive
Isometric
Positive
Positive
Isometric
Positive

0.956
0.956
0.889
0.921
0.904
0.944
0.884

**
**
n.s.
**
*
n.s.
**

(3)

TS
MS
DF
AL
PL
DN
DT

79
92
96
92
91
65
65

0.921
1.034
0.982
1.176
1.095
0.990
1.316

0.313
0.208
0.100
0.076
0.080
0.102
0.036

Negative
Isometric
Isometric
Positive
Positive
Isometric
Positive

0.882
0.957
0.973
0.974
0.949
0.931
0.944

*
n.s.
n.s.
**
**
n.s.
**

α and ln β are the allometric coeﬃcient and constant, respectively. The asterisk indicates the signiﬁcance levels of each allometric coefﬁcient from a value of 1 (t-test: *, P<0.05; **, P<0.01, n.s., no signiﬁcant diﬀerence). Stage (0), tail shape; Stage (1), diamond shape;
Stage (2), triangle shape; and Stage (3), boomerang shape.
2
The allometric equation y=βx α was used to determine the growth curves and patterns in each developmental stage, where x is the bodylength (cm), y is the length of the measurement point (cm), α is the allometric coeﬃcient, and β is the allometric constant. The growth
patterns of each measurement point were classiﬁed into three based on the signiﬁcance (t-test) of the allometric coeﬃcients applied:
positive when the allometric coeﬃcient was signiﬁcantly larger than 1, isometric when the allometric coeﬃcient was not signiﬁcantly
diﬀerent from 1, and negative when the allometric coeﬃcient was signiﬁcantly smaller than 1. All statistical analyses were made using R version 3.5.1 (R Core Team, 2018) running on RStudio version 1.1.456 (RStudio Team, 2016). Since no signiﬁcant diﬀerences(ANCOVA, P>0.05) were observed in the growth patterns of all measurement points (results are not shown here) between males andfemales, they were not separated in our analysis.
1

In Stage (3), AL showed 17.2±1.5% (P<0.01). On the other hand, PL increased from 8.7±1.0% inStage (1) to 11.5±1.2% in Stage (2) and to 12.4±1.2% in Stage (3) (P<0.05). The DN ratio ranged
from 9.8±0.8% to 10.2±0.8% for all the developmental stages (P>0.05). The DT ratio increased
through all the stages and ranged 4.2±0.5% in Stage (1), 7.7±1.6% in Stage (2), and 15.3±2.1% inStage (3) (P<0.01). The ratios of each measurement point to body length varied depending on thedevelopmental stage. Exceptionally, DN stayed within a certain range regardless of the developmental
stages. As the ﬂukes developed, the measurement points with increasing ratios were MS, AL, PL, andDT. The ratios of the other measurement points (TS and DF) changed with developmental stages.
Several authors have examined the fetal development of ﬂukes, including Štěrba et al. (2000) for
common dolphins (Delphinus delphis), pantropical spotted dolphins (Stenella attenuata), spinner dolphins (S. longirostris), and harbor porpoises (Phocoena phocoena), Nishiwaki et al. (1963) for sperm
whales (Physeter macrocephalus), and Ohsumi (1960) for ﬁn whales. This paper is the ﬁrst attempt toincorporate a quantitative measure of fetal growth into drawing the morphological development of fetal ﬂukes of the Antarctic minke whale.
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Table 3. The ratios of fetal ﬂukes to body length of the Antarctic minke whale at the developmental stages.
Measurement
point

N

(1)

TS
MS
DF
AL
PL
DN
DT

Developmental stage

The ratios of fetal ﬂukes tobody length (%)

P-value

Range

Mean (SD)

(2)

7
7
4
6
6
7
7

5.3–15.5
5.3–15.5
9.5–11.8
3.1–8.6
7.1–9.7
9.2–11.7
3.5–4.7

11.1 (4.0)
11.1 (4.0)
10.8 (1.0)
5.8 (2.1)
8.7 (1.0)
10.2 (0.8)
4.2 (0.5)

**
**
n.s.
**
**
n.s.
**

(2)

TS
MS
DF
AL
PL
DN
DT

14
14
14
14
14
13
14

17.9–26.6
17.9–26.6
8.8–10.6
8.3–15.3
9.4–13.6
9.3–11.2
5.1–10.3

22.4 (2.6)
22.4 (2.6)
9.7 (0.6)
11.7 (1.9)
11.5 (1.2)
10.1 (0.5)
7.7 (1.6)

(3)

TS
MS
DF
AL
PL
DN
DT

79
92
96
92
91
65
65

16.7–28.0
20.4–30.1
8.1–10.9
13.3–20.7
9.9–15.8
7.5–12.0
10.5–20.2

22.0 (2.5)
24.3 (1.9)
9.2 (0.5)
17.2 (1.5)
12.4 (1.2)
9.8 (0.8)
15.3 (2.1)

(3)

n.s.
**
**
**
*
n.s.
**

The asterisk indicates the signiﬁcance levels of diﬀerence to the average value of each ratio between the consecutive developmental stages (Mann–Whitney U test: *, P<0.05; **, P<0.01, n.s., no signiﬁcant diﬀerence). Stage (0), tail shape; Stage (1), diamond shape; Stage(2), triangle shape; and Stage (3), boomerang shape.

Ohsumi (1960) showed the growth patterns of ﬁn whale fetal ﬂukes (DF and PL in our study) tobody length. Their DF changed from a negative growth pattern to a positive one as the fetuses developed. This positive growth pattern was observed at the PL. Nishiwaki et al. (1963) observed the ratios
to body length of three measurement points of sperm whale’s fetal ﬂukes, which correspond to theTS, DF, and PL in our study. They found that the TS and PL/body length ratios increased, while DF
decreased. The growth patterns and ratios of the fetal ﬂukes of the Antarctic minke whale indicated a
rapid growth along the transverse axis direction during the fetal development. The results suggest thatthe growth rates of cetacean fetal ﬂukes at these measurement points vary from species to species.
Štěrba et al. (2000) compared the fetal age development of ﬂukes of four dolphin species: thecommon dolphin, the pantropical spotted dolphin, the spinner dolphin, and the harbor porpoise. They
found that the ﬂukes from each species started developing 32–42 days after conception, while wefound that the Antarctic minke whale ﬂukes began to develop at fetal age of 57.8 days. These results
are evidence that the development of the Antarctic minke whale ﬂukes begins about 15 days later thanthat of the dolphins, which would be key for comparing relative ratio to total gestation period and themethodological diﬀerences between previous studies and this study, which we plan to do in future investigations.

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FETAL DEVELOPMENT IN TAIL FLUKES OF THE ANTARCTIC MINKE WHALE

Fig. 5. The relationship between ratios of fetal ﬂukes to body length (y axis) and estimated fetal age (x axis)of the Antarctic minke whale. TS (a), MS (b), DF (c), AL (d), PL (e), DN (f), DT (g). The dotted lines indicate
the starting points of each developmental stage of fetal ﬂukes, from the left to the right: (0), (1), (2), and (3).
Stage (0), tail shape; Stage (1), diamond shape; Stage (2), triangle shape; Stage (3), boomerang shape.

Acknowledgements

We are grateful to all the crew members, researchers, and relevant organizations involved in the 2017/18 NEWREP-A
that was conducted in a harsh environment to collect samples for this study. Yujin Kim’s work was partially supported by agrant from The Korean Scholarship Foundation (2018–2019) and the Monbukagaku-Sho Honors Scholarship for Privately
Financed International Students (2017 and 2019).

References
Amano, M. and Miyazaki, N. 1993. External morphology of Dall’s porpoise (Phocoenoides dalli): Growth and sexual dimorphism. Can. J. Zool. 71 (6): 1124–1130.

Cetacean Popul. Stud. (CPOPS), Short noteVol. 3, 2021, 231–238

237

KIM, NISHIMURA, BANDO, FUJISE, NAKAMURA, MURASE AND KATO
Bando, T. 2017. Hokuseitaiheiyou niokeru nitarikujira Balaenoptera edeni brydei to iwashikujira B. borealis no keitai oyobi
seibutsugakutekitokuseichi no hikakukentou [Comparison of the morphological and biological characters of Bryde’s
whale Balaenoptera edeni brydei and sei whale B. borealis in the western North Paciﬁc.] (in Japanese). Ph. D. thesis,
Tokyo University of Marine Science and Technology, Tokyo. 149 pp.
Bando, T., Nakai, K., Kanbayashi, J., Umeda, K., Kim, Y., Nishimura, F., Yoshida, T., Tsunekawa, M., Yoshimura, I., Mure,
H., Kominami, T., Eguchi, H., Mogoe, T. and and Tamura, T. 2018. Results of the third biological ﬁeld survey of NEWREP-A during the 2017/18 austral summer season. Paper SC/67B/SCSP/08 of the Scientiﬁc Committee of the International Whaling Commission. 17 pp. [Available from the secretariat of IWC]
Huxley, J. S. 1950. A discussion on the measurement of growth and form; relative growth and form transformation. Proc. R.
Soc. B. 137 (889): 465–469.
Kato, H. and Miyashita, T. 1991. Migration strategy of southern minke whales in relation to reproductive cycle estimatedfrom foetal lengths. Rep. int Whal Commn. 41: 363–369.
Laws, R. M. 1961. Reproduction, growth and age of southern ﬁn whales. Discovery Rep. 3l: 327–486.
Nishiwaki, M., Ohsumi, S. and Maeda, Y. 1963. Change of form in the sperm whale accompanied with growth. Sci. Rep.
Whales Res. Inst. 17: 1–14.
Ogawa, T. 1953. On the presence and disappearance of the hind limb in the cetacean embryos. Sci. Rep. Whales Res. Inst. 8:
127–132.
Ohsumi, S. 1960. Relative growth of the ﬁn whale, Balaenoptera physalus (Linn.). Sci. Rep. Whales Res. Inst. 15: 17–84.
R Core Team. 2018. R: A language and environment for statistical computing. Version 3.5.1. R Foundation for StatisticalComputing, Vienna, Austria. https://www.R-project.org/
Roston, R. A., Lickorish, D. and Buchholtz, E. A. 2013. Anatomy and age estimation of an early blue whale (Balaenoptera
musculus) fetus. Anat. Rec. 296 (4): 709–722.
RStudio Team. 2016. RStudio: Integrated development environment for R. Version 1.1.456. RStudio, Inc., Boston, MA. http://
www.rstudio.com
Schneider, C.A., Rasband, W.S. and Eliceiri, K.W. 2012. NIH Image to ImageJ: 25 years of image analysis. Nat. Methods. 9:
671–675.
Štěrba, O., Klima, M. and Schildger, B. 2000. Embryology of dolphins. Staging and ageing of embryos and fetuses of somecetaceans. Adv. Anat. Embryol. Cell Biol. 157: 1–133.
Thewissen, J. G. M. 2018. Highlights of cetacean embryology. Aquat. Mamm. 44: 591–602.

Received: September 19, 2020
Accepted: December 4, 2020
Published online: March 3, 2021

Appendix
Formulas for estimating fetal age of the Antarctic minke whale
We used formula (1) based on Kato and Miyashita (1991) to estimate the fetal age (t, expressed indays) when the body length was 15 cm or more. The growth rate of the fetus changes with the formation of the placenta (Laws, 1961). The placenta of this species is formed when the body length is
15 cm (Kato and Miyashita, 1991). Bando (2017) studied Bryde’s (B. edeni brydei) and sei whales (B.
borealis) fetuses, and assumed that days after conception (i.e., fetal age) of fetuses with a body lengthof less than 15 cm were proportional to their body length. This study made a similar assumption. First,
we calculated the fetal age at 15 cm in body length using formula (1) and estimated it at 92.2 days.
Subsequently, we adapted t=aL to estimate the growth coeﬃcients (a), which we calculated as 6.147.
Formula (2) was used when the body length was less than 15 cm.

238

t = 1.622 L0.892 +74(1)

t = 6.147 L(2)

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