SIAMESE TWINS OF MINKE WHALESOF THE SOUTHERN HEMISPHERE

VALERY! L. ZINCHENKO*ANDMIKHAIL V. IVASHIN**

Several authors have examined the whales which were raised on board more
attentively and with more interest during the past southern ocean whaling
expeditions. It gave the opportunity to reveal rare cases of atavism (Ogawaand Kamiya, 1957; Nemoto, 1963; Ohsumi, 1965; Zemsky and Berzin, 1961).
Various cases of abnormalities in the development of foetus stage (Nishiwaki,1957; Ohsumi, 1959; Ivashin, 1960, 1977) and cases of foetus mortality andextrauterine pregnancy (Ivashin, 1960, 1963, 1977; Ichihara, 1962; Kamiyaand Miyazaki, 1974) were recorded.
Formation of conjoint pair of foetus is a pathological case, such cases arerare among marine mammals. Kawamura ( 1969) was the first to describe
Siamese twins of Cetaceans. Zemsky and Budylenko (1970) examined female
humpback whale of the southern hemisphere (body length - 12.7 m), in theuterine horn of which Siamese twins were found. Japanese scientists
registered a blue-white dolphin with abnormal twins, which was collected incoastal water of Japan (Kawamura and Kashita, 1971; Kamiya, Miyazaki andShiraga, 1981).
On 4 January, 1981, one female minke whale (body length-9.0m) with apair of Siamese twins was caught, and such twins are for the first time recorded.
It was taken at 64 ° 35 'S, 81 ° 05 'E. In the left uterus horn there were two
females of 50.5 and 49.0 cm in total length, conjointing in abdominal andpartly in lateral areas of the body. Their dorsal and abdominal sides could bedistinguished (Figs 1 and 2). This case can be considered as ventropagus(Patten, 1959).
The foetuses were connected at the tip of the mouth to the umbilicus,
the connected area was about 20.5 cm, that is 40.6% of the total length. The
following parts were separate: upper jaws at the tip of the mouth, partly
lower jaws, caudal peduncles, (which dranched only at the umbilicus level,
where two umbilical cords came together, connected by a mesentery). The
distance between both rostrums was 3.6 cm. The right foetus (with the bodylength - 120 cm) had harelip on the lower jaw (Fig. 3), as in the case with
* Odessa Branch, 53 Mechnikov, GSP-983, Odessa, 270020, USSR** VNIRO, 17, V. Krasnosel'skaya, Moscow, B-140, 107140, USSR
Sci. Rep. Whales Res. Inst.,
No. 38, 1987, 165-169

166ZINCHENKOAND I
VASHIN. MinkewhaleSiamesetw
ins(dorsalside)
.
Fig.I

長F
ig.2.MinkewhaleSiames
etw
ins(abdominalside).

Sci.Rep. Wh
alesR四 I
ns.,
tNo.38,1987

SIAMESETWINSOFMINKEWHALES

167Fig.3.Headofminkewha
leSiamesetwins(from t
heabdominalside).Thec
leftlowerjawcanbes
een.

humpb
a
ckwha
l
edescrib
edbyZemskyandBudylenko(1970)
.Da
t
aont
het
wi
nsme
a
surementsa
r
egi
v
eni
nTabl
e1
.Thet
wi
nsc
ons
i
der
edha
dc
le
ar
ly
man
i
fest
edasymmetricd
is
posi
t
i
onoft
hee
yes,pectora
lf
insandmouths.Ont
hedorsalsidetheti
pofthemouthc
om monfort
hetwofoetuseswasshifted
moreforwardt
hanontheabdomi
nals
ide;pector
alfinswered
i
s
p
lac
e
di
nt
hec
au
da
ldi
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e
c
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i
de,t
hee
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achf
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t
u
swass
hi
f
t
edi
nt
hed
i
r
e
ct
i
o
noft
her
ost
r
u
m.Thedistancebetweent
hee
ye
sont
heconnectedsi
dewas 1.
8cm,ont
heoppositesi
de1
1.5cm(Figs1and2).Thedist
ance
betw
eengenitalopeningswas5cm.Vi
br
issa
eont
hef
oetusesheadswered
is‑
tr
ibut
edune
v
enly(Table2).Abdominals
tripswereno
tsee
n.Thecombine
dwei
gh
toft
hetw
in
swas3,200g
.
Thel
ef
tov
ar
ycole
ct
ed fromt
hec
al
fhavi
ngt
hetwi
nswei
ghed445g
andwas 1
4 × 7.
5 × 3cmi
nsize.Onlyonef
unctioni
ngcorpusletumwas
obser
v
e
da
ndwas7.
5c
mi
ndia
met
era
nds
i
xc
or
por
aa
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at
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sth
et
wi
nswer
ei
d
ent
i
c
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s,comin
gfromonefollic
le.The
r
i
g
h
tov
ar
yw
a
s1
5.
5× 7.
0× 3.
5c
mi
nsi
z
e,it
swei
gh
twas285g
.Atl
e
astt
hi
r
te
en
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ayer
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e
c
o
gn
is
edont
heearplugt
houghitwasslightlyhar
dt
oread.

Sc.
iRep.WhalesRes.I
nst.,
No.38,1987

168

ZINCHENKO AND IVASHINTABLE 1. MORPHOLOGICAL DATA OF SIAMESE TWINS OF MINKE WHALES
Right foetus

Left foetus
cm%cm%

Left;Rightside side

Left;Rightside side

Left;Rightside side

Left;Rightside side

50.5
7.3
12.5/8.4
11.6/10.7
-15.5
14.0
4.3/4.3
24.0
15.7
1.3
2.0
3.5

100
14.5
24.8/16.6
23.0/21.2-/10.927.7
8.5/8.5
47.5
31.1
2.6
4.0
6.9

49.0
6.8
8.4112.3
12.5110.7
4.9/12.0
4.5/4.5
23.5
15.7
1.2
2.0
3.3

100
13.9
17.1125.l
25.5/21.8
10.0124.5
9.2/9.2
48.0
32.0
2.4
4.1
6.7

6.8/6.4
8.4/8.0
7.517.5
2.3/2.3-/16.59.3
5.3
5.8/5.8
11.3

13.5/12.7
16.6/15.8
14.9/14.9
4.6/4.6-/32.7
18.4
10.5
11.5/11.5
22.4

6.8/5.7
7.9/7.9
7.517.5
2.3/2.3
16.7 I 9.5
5.3
5.8/5.8
11.2

13.9/11.6
16.1/16.l
15.3/15.3
4.7/4.7
34.1/ 19.4
10.8
11.8/11.8
22.9

3.5
1.3

6.9
2.6

5.7/7.0
1.1

11.6/14.3
2.2

17.0/21.5
7.3
9.5

33.7/42.6
14.5
18.8

20.5/18.0
7.6
9.3

41.8/36.7
15.5
19.0

Measurements

I. Total length
2. Tip of the snout to the middle of blow holes
3. Tip of the snout to mouth angle
4. End of the snout to eye centre
5. Eye centre to the centre of the ear
6. Tail fork to the notch of the caudal fin
7. Width of the tail flukes
8. Tail fork to umbilicus
9. Tail fork to anus
10. Anus to genital opening (Center to center)
11. Height of the dorsal fin
12. Length of the dorsal fin base
13. Length of the pectoral fin from the end
to the pit
14. Length of the pectoral fin on the external edge
15. Pectoral fin curve length
16. Maximum length of the pectoral fin
17. Length of the head (from snout to ear)
18. Breadth of the head
19. Height of caudal peduncle of the dorsal fin
20. Length of flukes from the fork to the end
21. Span of flukes
22. From the end of the upper jaw to the endof the lawer jaw
23. Length of the blow hole
24. From the snout to the beginning of thepectoral fin
25. Width of the body at the umbilicus level
26. The distance between pectoral fins

TABLE 2. NUMBER OF VIBRISSAE OF SIAMESE TWINS OF MINKE WHALES
Left foetus

Right foetus

Location
Right

Left

Right

312322322229767Left
Blow hole
Upper jaw
Lower jaw
Lower jaw
protuberance

Sci. Rep. Whales Res. Inst.,
No. 38, 1987

SIAMESE TWINS OF MINKE WHALES169REFERENCES
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IvASHIN, M. V., 1963. The case of extrauterine pregnancy in sei whale (Balaenoptera borealis Lesson). Zool.
zh., 42(8): 1275-1277.
IvASHIN, M.V., 1977. Cases of pathological embryogenesis of minke whales, Balaenoptera acutorostrata(Cetacea, Balaenopteridae) of the Antarctic part of the Indian Ocean. Zool. zh., 56(11): 1736-1739.
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Sci. Rep. Whales Res. Inst.,
No. 38, 1987