OCCURRENCE AND RUPTURE OF VAGINAL BAND
IN THE FIN, SEI AND BLUE WHALESSEIJI OHSUMI*
The vaginal band is present crossing the entrance of vagina in some baleen whales.
It was firstly reported by Mackintosh and Wheeler (1929) on the southern fin whales(Balaenoptera physalus) and the blue whales (B. musculus). After then, the presence ofthe band was reported for the southern fin whale (Wheeler, 1930; Laws, 1961),
the southern humpback whale (Megaptera novaeangliae; Matthews, 1937), the northern fin whale (Ohsumi et al., 1958) and the North Pacific right whale (Eubalaena
glacialis; Omura, 1958).
As Mackintosh and ·wheeler described, the vaginal band is not an abnormality,
but is found in fairly large percentage. However, few one have noticed the occurrence of the band in the whales, and there are few data on the subject.
The vaginal band appears to be analogous to the hymen in the mankind. And
I think that the occurrence and rupture of the band is useful for the examination of
the reproductive behavior and physiology in the whales. In practice, we have rare
chances to observe copulation or parturition of whales. But the occurrence andrupture of the vaginal band will represent the experience of copulation or parturition of the whales.
In this point of view, I examined the frequency occurrence of vaginal band andits tag in relation to the development of the whales.
MATERIAL AND METHOD
It is difficult to observe a vaginal band of a whale without insertion of observer's
hand into the vulva. Because, in most immature female whales, the genital grooveis closed, so that little can be seen of the genitalia. Vaginal band is present accrossing the vulva, and attach at the anterior and posterior borders of the entrance ofvulva. Sometimes, mostly in mature females, tag of the vaginal band is found at
entrance of vagina. Therefore, I inserted my hand into vagina of the whale before
the time of £lensing, and palpated the existence of vaginal band or its tag.
Mammary gland was observed and determined its maturity. Immature andpubertal mammary gland is thin and pale pinkish-white in colour, while mature
gland is thicker and brown in colour (Ohsumi et al., 1958). A pair of ovaries wasobserved on the follicle, corpus luteum and corpus albicans.
Then, the five stages of development and sexual maturity of examined whales
were divided as follows :Immature Mammary gland is immature, and the ovaries are rather small. Graafian follicles are too small to be found by naked eyes.

* Far Seas Fisheries Research Laboratory, Shimizu
85

86

OHSUMI

Prepubertal

Mammary gland is immature. Ovaries elongate, .and the surface israther smooth. The development of Graafian follicles leads to the formation ofround protuberances. But there is no corpus luteum nor corpus albicans in thepair of ovaries.
Pubertal Mammary gland is still immature, but its colour becomes pinkish. In
ovaries, there is at least one corpus luteum or corpus albicans. It is considered that
one or more ovulation occurred already in the whale of this stage, but the pregnancy
or at least parturition has not experienced. Because in the whale which have neverbeen pregnant or are pregnant for the first time, mammary gland differs from thestate of the gland in immature whale only in a slightly better development of thelobes (Mackintosh and Wheeler, 1929).
First pregnant Mammary gland remains in the immature appearance, but the colour
becomes pinkish. There is embryo or foetus in the uterus, and of course, there is atleast one corpus leteum in the ovaries. As van Lennep and van Utrecht (1953)
and Laws (1961) remark that in the whales the lobules alveoli of mammary gland
do not develop until the end of pregnancy. First pregnancy is easily distinguishable
by observing the mammary gland. vVe must consider the case of abortion, but
it is difficult to find the experience of abortion in the whale.
Multiparous Mammary gland is mature. And there is more than one corpus albicans in the ovaries. Chittleborough (1958) found that in the humpback whales
which were very close to the time of parturition, the lobules and labeoli were welldeveloped and colostrum was present in most cases. And after the first lactation,
mammary gland becomes quite different from that of the gland which has not yet
been functional.
In this stage are included the lactating and resting stages of primiparious animals,
because they are not able to distinguish from the multiparous animals exept the individual with only one corpus albicans in the ovaries.
The occurrence of vaginal band or tag is summed up in the above five stages ofsexual maturity respectively.
The investigations of vaginal band were made on the fin, sei and blue whales
on board of factory ships in the Antarctic in 1958/59 season and in the northernpart of the North Pacific in 1961 and 1964 seasons. The numbers of individuals
examined are as follows:
Antarctic
Fin whale
Sei whale
Blue whale

70

2North Pacific

Total

317

387

206

206

12

14

. OCCURRENCE OF VAGINAL BAND OR ITS TAG
Tables I, 2, 3 and 4 show the occurrence of vaginal band and its tag in the five stagesof sexual maturity for the northern and southern fin whales, northern sei whales andblue whales respectively.

VAGINAL BAND

87

Immature stage
Of the total of 84 immature northern fin whales, the band was present in 35(41.6 %), and in the total of 42 immature southern fin whales, the band was present
in 17 (40.5 %). The frequency occurrences of vaginal band are similar each otherin the northern and southern fin whales. These figures are higher than that which
was reported on the southern fin whales by Mackintosh and Wheeler (1929). They
reported that the vaginal band was present in 31 (21.4 %) of the total of 145 immature
females.
TABLE I. OCCURRENCE OF VAGINAL BAND IN THE FIVE STAGES OFSEXUAL MATURITY FOR THE NORTHERN FIN WHALESBand present
Actual figure
Immature
Prepubertal
Pubertal
First pregnant
Multiparous
Total
Per cent
Immature
Prepubertal
Pubertal
First pregnant
Multiparous

Tag presentBand absent

Total

62

2
3
8
38
51

49
33
5
18
99
204

84
59
8
29
137
317

41.6
40.7
0.0
10.3
0.0

0.0
3.4
37.5
27.6
27.7

58.4
55.9
62.5
62.l
72.3

35
24
3

TABLE 2. OCCURRENCE OF VAGINAL BAND IN THE FOUR STAGES OFSEXUAL MATURITY FOR THE SOUTHERN FIN WHALES
Actual figure
Immature
Prepubertal
Pubertal
Multiparous
Total
Per cent
Immature
Prepubertal
Pubertal
MultiparousBand present

Tag presentBand absent

Total

17
8

3

25
11

26

5

3
39

42
22
2
4
70

40.5
36.4
50.0
0.0

0.0
13.6
50.0
25.0

59.5
50.0
0.0
75.0

However, they also described that not all these whales were examined on thisstructure, but it was definitely not present in 40 immature fin whales. The
individuals which were not examined should be excluded in the calculation of thefrequency. In their paper, if71 immature whales were examined on this structure,
the frequency occurrence is recalculated to be 43. 7 %· This figure is similar to myresult. In this point of view, the frequency occurrence (14 %) of vaginal band in
the foetal stage by Mackintosh and \Vheeler is also too low, because they reported

OHSUMI88

five possessed band, while two definitely did not.
Of 22 immature northern sei whales, vaginal band was present in six (27.3 %).
Matthews (1938) examined seven immature southern sei whales and one (14.3 %)possessed the vaginal band. This figure is lower than my result, but his materials
are few to be compared the difference of frequencies between the two races.
I confirmed the presence of vaginal band in the immature female blue whale.
That is to say, two immature females were examined on this structure and one undoubtly possessed an unbroken vaginal band. Mackintosh and Wheeler (1929)
reported that a blue whale possessed only a tag of vaginal band.
There is no individual which possesses a tag in the immature stage for the examined 150 female whales.
TABLE 3. OCCURRENCE OF VAGINAL BAND IN THE FIVE STAGES OFSEXUAL MATURITY FOR THE NORTHERN SEI WHALES

Actual figure
Immature
Prepubertal
Pubertal
First pregnant
Multiparous
Total
Per cent
Immature
Prepubertal
Pubertal
First pregnant
Multiprous
TABLE 4.

Band absent

Total

8

6
40
50

16
11
1
12
108
148

22
17
1
18
148
206

27.3
11.8
0.0
0.0
0.0

0.0
23.5
0.0
33.3
27.0

72.7
64.7
100.0
66.7
73.0

Band present

Tag present

62

4

OCCURRENCE OF VAGINAL BAND IN THE THREE STAGES OFSEXUAL MATURITY FOR THE BLUE WHALESBand present

Actual figure
Immature
Prepubertal
Multiparous
Total
Remarks:a)c)

Tag presentBand absent

Total

1a>

2

!bl

5
7
14

2

Northern whale, b) Southern whale,
One southern whale and three northern whales.

Prepubertal stage
There were the individuals of which tag was observed in the prepubertal stage.
Of 59 prepubertal northern fin whales, two (3.6 %) possessed a tag. However,vaginal band was still present in 24 (40.7%). Mackintosh and Wheeler (1929)
also recorded an individual with vaginal band and with enlarged Graafian follicle
in the ovary. On the present result, in 22 southern fin whales, three (13.6 %) possessed a tag, and eight (36.4 %) possessed a band in the prepubertal stage. In the

VAGINAL BAND

89

17 northern sei whales, tag was present in four (23.5 %), and two (11.8 %) had stillvaginal band. Of five blue whales, there was no individual with tag, but one (20 %)had unbroken band in this stage.

Pubertal stage
I have small data on the examination of the vaginal band in this stage.
Of the total of eight northern fin whales, three (37 .5 %) possessed a tag, andthere was no individual with band. However, in two southern fin whales, onepossessed an unbroken band. Two similar cases were recorded in the southern fin
whales by Mackintosh and Wheeler (1929) and Wheeler (1930). One northern sei
whale has no sign of vaginal band.
First pregnant stage
It is worth notice that there are individuals with unbroken vaginal band, although they are pregnant. In 29 northern fin whales of the first pregnant stage,
three (10.3 %) still possessed unbroken vaginal band. Biological data of the three:individuals are shown in Table 5. Laws (1961) introduced a similar record by D.F.
S. Raitt on a pregnant southern fin whales which had an unbroken vaginal band.
These results will show that it is probable that the vaginal band does not always rupture at the time of coition. This problem will be discussed in the following chapter.
TABLE 5. BIOLOGICAL DATA OF THE THREE NORTHERN FIN WHALESWHICH WERE FIRST PREGNANT AND WITH UNBROKENVAGINAL BAND
Serial no.

Body length(feet)

10:\'Ky 154
10NKy1413
10."JKyl424

58
63
64

Mammary gland

Age Corpora no.
(Years)M t .ta un yThickne(mm)

Foetus1-0, 0-0
0-0, 1-1
1-0,0-0

Immature
Immature
Pubertal

23
19
28

3 106 cm
¥ 246
¥ 212

13
14

,.....__...__

SS

In the northern fin whales, eight (27.6 %) were with tag. In 12 northern sei
whales, tag was present in six (33.3 %), and there was no individual which has unbroken vaginal band. I have no material on this structure for the southern fin whaleand for the blue whale of the first prgnant stage.

Nlultiparous stage
In this stage, the individual with unbroken vaginal band did not occur, butthere were the whales with tag.
Of 137 northern fin whales, 38 (27.7%) possessed a tag. According to Mackintosh and Wheeler, in the total of 206 mature southern fin whales, the tag wasobserved in 14 (6.8 %). This frequency occurrence seems to be low, because theydescribed that not all these whales had been examined on this structure. Furthermore, in the present paper, the disappearance of tag according to age will be examined, and the result will show that the rate of disappearance is not so much.

90

OHSUMIIn 148 northern sei whales, 40 (27.0 %) possessed a tag. On the other hand,
Matthews (1938) reported that a tag had been present in three (5.4%) out of 52
adult southern sei whales.
Seven northern blue whales in this stage were examined on this structure, andall individuals were absent in the vaginal band or tag.
RUPTURE OF VAGINAL BAND AND ITS BIOLOGICAL MEANINGIn the previous chapter, the occurrence of vaginal band and tag was shown in eachstage of sexual maturity of whales. The occurrence of unbroken band and tagchanges according to the development of the stage. I want to discuss on the ruptureof the band and its meaning in the sexual behavior and physiology of the whale in
the present chapter.
TABLE 6. RATIO OCCURRENCE OF VAGI'.\'AL BAND AND TAG IN THE
FIVE STAGES OF SEXUAL MATURITY, I'.\'CLUDING ALL \\:HALESEXAMINED
Band

Actual no.
Immature
Prepubertal
Pubertal
First pregnant
Multiparous
Total
Per cent
Immature
Prepubertal
Pubertal
First pregnant
Multiparous

59
35
I

3
98
100.0
74.3
20.0
21.4
0.0

Tag

Total

9
4
14
79
106

59
44
5
17
79
204

0.0
25.7

80.0
78.6
100.0

Whalesexamined

Per cent of band andtag to whales examined

150
103
11

47
296
607
39.3
42.7
45.4
36.2
26.6

Table 6 shows the ratios of vaginal band and the tag in the five stages of sexual
maturity summarizing the all materials of the three species. In the immature stage,
there were 59 females with unbroken vaginal band, but there was no whales withtag. It is considerable from this result that the vaginal band is not broken in thisstage, and then copulation will be not took place in this stage. Brown and Norris(1956) observed some sexual play of a infant bottlenose dolphin (Tursiops truncatus).
However, it is doubtful that a young whale female really coputates or breaks its
vaginal band by the sexual play.
Tag appears in the prepubertal stage (26 %). This fact will mean that there isa possibility of experience of copulation or sexual play on at least one fourth of whalesin this stage, for it can not be considered that the vaginal band cuts off without theresult of copulation, considering with the behavior of Balaenopterids. If so, theovulation will not be related with the stimulus by copulation in these whales, because
the experience of ovulation must not be recognized in this stage.

VAGINAL BAND

91

The number of whales examined was small on the pubertal stage. But thepercentage of tags increases in this stage (80 %), and it is almost the same as that of
the first pregnant stage. From this fact, it is estimated that the female whale becomes to copulate commonly in the pubertal stage. There was one fin whale withunbroken vaginal band. However, we cannot regard this whale as an unexperienceof copulation, for some of the first pregnant whales have unbroken band, although
they obviously have experiences of copulation.
TABLE 7. OCCURRENCE OF VAGINAL BAND AND TAG ACCORDING
TO CORPORA NUMBER FOR THE '.\!ORTHERN FIN WHALES
No. of corpora
0
1- 2
3- 4
5- 6
7- 8
9-10
11-12
13-14
15-16
17-18
19-20
21-22
23Total

Band
59
3

62

Tag
2
18
12
6
4
2
4
2

51

Absent
82
38
21
18
15
3
8
3
3
2

Total
143
59
33
24
19
5
13
10
3
4
2

2
204

2
317

9

TABLE 8. OCCURRENCE OF VAGINAL BAND AND TAG ACCORDIND
TO CORPORA NUMBER FOR THE NORTHERN SEI WHALES:\lo. of corpora
0
1- 2
3- 4
5- 6
7- 8
9-10
11-12
13-14
15-16
17-18
19-20
21-22
Total
*:

Band
8

Tag
4
10
9
8
4
7
3
2
2

,.\bsent
27
20
26
21
18
7
12
5
6
2

Total
39
30
35
29
22
14
15
7
8
3

8

50

146*

204

Excluded two whales which are multiparous but lost one ovary.

It is very interesting that three fin whales which were first pregnant and had
unbroken vaginal band were found. Concerning on this fact, the duration of copulation in the whale is considered to be generally very short. According to the observation in aquariums, (Brown and Norris, 1966; Tavolga and Essapian, 1961 ),the bottlenose dolphin (Tursiops truncatus) lasted only at most ten seconds in copula-

OHSUMI92

tion. Brown and Norris showed a figure of copulation of the dolphin, and Tavolga
and Essapian took some photographs of the same behavior. These figures show that
only tip or half of the penis inserted in the vulva. Considering from these observations, it will be convinced that the fertilization can succeed in without the break ofvaginal band in the whales.
Primiparous and multiparous whales have no unbroken vaginal band. Thismeans that at the time of parturition the all bands break off.
The percentage of existence of band or tag in the multiparous whales is clearlylower than the whales of other stages. This lets us consider that the tag of vaginal
band gradually absorves accompanying with the time after rupture. Then, I calculated the ratios of band and tag in each age classes. As the age class, I used thenumber of corpora lutea and corpora albicantia in the ovaries of the examined whale.
20
23-

40

60

80

20

40

60

80

60

80

Sei whale

Fin whale

19-22.... 15-18
0

8"' 11-14...."

0... 7-10
..c
"'
s 5-6
;:J

z

3-4
1-2
0
20

40

60

Frequency (%)

80

'

20

40

Frequency (%)

Fig. !. Change in percentage of frequency occurrence of the female fin and sei
whales with vaginal band, tag and band absent accompanying with the incrementof corpora number.
Black: Band present, Stripe: Tag present, Blank: Band or tag absent.

Tables 7 and 8 show the number of whales with band, tag and without band inseveral are classes. And Fig. 1 shows the change ofratio of band and tag to the total
whales examined in each age classes accompanying with the increment of corpora
number on the fin and sei whales. The frequency occurrence of band and tag tends
to decrease with the increase of corpora number. This tendency is more clear in
the fin whale than in the sei whale. Although there are relatively few materials
on the whales which have many corpora in the ovaries, the tag was not observed forthe whales with 19 corpora and over.
This result will confirm that the vaginal band gradually absorves after its

93

VAGINAL BAND

rupture. However, it seems to take long time by the complete absorption of tag,considering the rate of increment of corpora in the ovaries. The annual rate ofincrement of corpora number is 1.43 according to Laws (1962) and 0.5 according to
Ohsumi (1964).
FREQUENCY OCCURRENCE OF VAGINAL BAND AND DISCUSSION\Ve can recognize from above chapters that the tag represents the remain of thevaginal band, and the tag gradually disappears in the multiparous stage. Therefore, the multiparous whales should not be used to get the true frequency occurrence of vaginal band in the whales.
In this point of view, I calculated the frequency occurrence of vaginal band
(unbroken band plus tag) for each whale populations summing up the immature,
prepubertal, pubertal and the first pregnant stages as shown in Table 9. The confidence intervals of 90 per cent are also calculated based on the materials. The
figures are also shown in the same Table.
TABLE 9.

COMPARISON OF FREQUENCY OCCURRENCE OF VAGINAL BAND AMONG
THE THREE SPECIES OF BALAENOPTERA IN SUM OF IMMATURE,
PREPUBERTAL, PUBERTAL AND FIRST PREGNANCY STAGESBand or tag present

Species LocalityF'h { Northern Hem.
m w a1e Southern Hem.
Sei whale Northern Hem.
Blue whale{ Northern andSouthern Hem.

90 % confidence interval of per cent frequenc;•F'h { Northern Hem.
m.w a 1e Southern Hem.
Sei whale Northern Hem.
Blue whale{ Northern andSouthern Hem.

------------..

No. of whales
75
30
18

2

Per cent
41.7
45.5
31.0

27.6

Band absent.----""---..

No. of whales
105
36
40

5

Per cent
58.3
54.5
69.0

Total

72.4

7

35.7-47.7
35.9-55.6
22.4-41.7

52.3-64.3
44.4-64.1
58.3-77.6

11.1-45.0

55.0-88.9

180
66
58

The highest frequency occurrence of the vaginal band is 45.5 %in the southern
fin whale, and the lowest is 27.6 % in the blue whale. However, 90 per cent confidence intervals of the frequency occurrence overlap each other among the four
populations. Using chi-square test, under 5 per cent of significant level, the equallity of frequencies was not able to be denyed.
In conclusion, the vaginal band will occure in from a quater to a half of thefemale Balaenopterid whales. It is important to examine the vaginal band for the
foetal stage, but I have yet few materials on this stage. It is relatively difficult to
examine the vaginal band on the small foetus in the field, and I think it is better toexamine the band after fixation with formallin in such cases.
It is obvious that there are vaginal band in other baleen whales, but the frequency
occurrence have not yet obtained because of scarcity of the materials.

94

OHSUMII have no report on the occurrence of vaginal band for the toothed whales. I
have investigated the vaginal band on several toothed whales (Sperm whale, Physetercatodon; Bairde's beaked whale, Barardius bairdi; Bottlenosed dolphin, Tursiops
gilli), but I have not yet found the vaginal band or its tag.
SUMMARY

1. Vaginal band occures in the fin, sei and blue whales.
currence of it before the rupture is calculated as follows:
North Pacific fin whale:
Antarctic fin whale:
North Pacific sei whale:
North Pacific and Antarctic blue whale:

The frequency oc-

41.7±6.0%
45.5± 10. l %31.0± 10. 7 %27.6± 17.4 %2. In the immature stage, vaginal band does not rupture, but after prepubertal
stage its tag becomes to be present.
3. There is a posibility of experience of copulation or sexual play in the prepubertal and pubertal stages at least in the case of Balaenopterid whales.
4. Vaginal band does not always rupture in copulation, for there were threecases in which the first pregnant fin whales had unbroken vaginal band.
5. Vaginal band disappears gradually after the rupture, but it takes long timeby the complete absorption.
6. There have been no record on the occurrence of vaginal band for the
toothed whales.
REFERENCESBROWN, D. H. and NoRRis, K. S. (1956). Behavior of a captive and wild cetaceans. J. Mammal. 37: 311336.
CHI'ITLEBOROUGH, R. G. (1958). The breeding cycle of the female humpback whale, Megaptera nodosa (Bonnaterre). Aust. J. Mar. Freshw. Res. 9(1): 1-18.
LAws, R. M. (1961). Reproduction, growth and age of southern fin whales. Discove1y Repts. 31: 327-486.
LENNEP, F. W. VAN and UTRECHT, W. L. VAN (1953). Preliminary report on the study of the mammary
glands of whales . .Norsk Hvalfangst-Tid., 42(5): 249-258.
MACKINTOSH, N. A. and WHEELER_, G. F. G. (1929). Southern blue and fin whales. Discove1y Repts., 1: 257540.
MATTHEWS, L. H. (1937). The humback whale, Megaptera nodosa. Discovery Repts., 17: 7-92.
- - (1938 a). Notes on the southern right whale, Eubalaena australis. Discovery Repts., 17: 169-182.
- - (1938 b). The sei whale, Balaenoptera borealis. Discovety Repts., 17: 183-290.
0HSUMI, S. (1964). Examination on age determination of' the fin whale. Sci. Rep. Whales. Res. Inst. 18:
49-88.
OHsuMr, S., NISHIWAKI, M. and HIBIYA, T. (1958). Growth of fin whale in the northern Pacific. Sci. Rep.
Whales Res. Inst., 13: 97-133.
O~mRA, H. (1958).
North Pacific right whale. Sci. Rep. Whales Res. Inst., 13: 1-52.
SLIJPER, E. G. (1958) Walvissen (Translated by Pomeraus, A. J., Hutchinson, London, 1962), pp. 475.
TAVOLGA, M. C. and EssAPIAN, F. S. (1957). The behavior of the bottlenosed dolphin (Tursiops truncatus):
Mating, pregnancy, parturition and mother-infant behavior. :(oologica, 42(1): 11-31.
WHEELER, G. F. G. (1930) The age of fin whales at physical maturity. Discovery Repts., 2: 403-434.