UNUSUAL MINKE WHALE WITH DEFORMED JAW
HIDEHIRO KATOWhales Research Institute, Tokyo

An unusual minke whale (Balaenoptera acutorostrata) was captured by the Japanesewhaling fleet on 27 January 1979 in Area IV of the Antarctic (serial no. 1645).
The rostrum of this whale was abbreviated and bent towards the lower jaw which
was rather wide compared with a normal animal (Fig. 1). There are several
TABLE 1. BODY MEASUREMENTS AND OTHER DATA OF UNUSUALMINKE WHALE COMPARED WITH TWENTY NORMAL WHALES
Twenty normal whales
Unusual whaleRange
Serial no.
Date of catchPosition of catchSex
Age (yrs.) (number of layers in ear plug)
Thickness of blubber (cm)Body proportion (cm)
Toto! length, tip of snout to notch of flukes
Tip of snout to center of blowhole
Tip of snout to center of eye
Tip of snout to ear
Tip of snout to tip of lower jaw
Length of ventral grooves (max.)
Umbilicus to end of ventral grooves
Notch of tail flukes to center of anus
Notch of tail flukes to tip of dorsal fin
Half of the girth, at umbilicus
Half of the girth, at anus
Dorsal fin, vertical height
Flipper, tip to anterior insertion
Flipper, tip to axilla
Flipper, greatest width
Tail flukes, tip to tip
Tail flukes, notch to the nearest part of the anterior
margin of the tail flukes
Half number of ventral grooves, at anterior
insertion of each flipper (no.)
Skull (cm)Length, codyles to tip of premaxilla, straight
Breadth, frontal
Reproductive organs
Mammary gland (length, width, depth ; cm)
Number of corpora lutea and albicantia (no.)
Sci. Rep. Whales Res. Inst.,
No. 31, 1979, 101-103

1645
27/Jan./1979
67°09'S, 71°48'E
Female40+4.5Mean

1569-2061
24/Jan.-9/Feb./1979
Antarctic
Females
3.5-6.0

4. 7

870
100
144
181
28
461
49
261
280
186
131
33
140
105
34
219
60

860-890125-144
158-185
198-230

873.5
134.9
171.9
215.2

436-492
15-53
217-248
238-273
191-245130-156
28-40
121-151
92-11030-35
223-270
55-65

466.5
28.8
235.0
252.4
223.8
139.7
34.8
136.4
100.8
32.9
243.6
60.0

24

20-28

25.0

180
116

196-223
106-120

211.8
112.4

129,22,2.9
1-12, 0-10

102

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aw
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同Sci.Rψ.IVhalesRes.Inst.
,No.31,1979

DEFORMED JAW103

This whale was an old female of 8. 7 m in length and pregnant with one fetus(female, 30.3 cm long). The viscera and fetus of this whale were completely normal. A comparison of its proportions and other data with those for twenty normal
whales (all females, 8.6-8.9 m in length) is given in Table 1.
In all three measurements of the head region, namely, the length from tip of
the snout to center of blowhole, to center of eye and to ear, whale no. 1645 was
shorter than normal. There also seemed to be a significant difference in the lengthfrom the tip of the snout to the tip of the lower jaw, but no data were recorded on
this measurement for normal whales.
As shown in Table 1, whale no. 1645 has longer tail than normal. This may
be indicated that actual body length of this whale is longer than 8. 7 m if it had
normal jaw. The skull of this individual was shorter than normal, but its breadthfell within the range for whales of the same body length.
Furthermore, although the girth (half, at umbilicus) of whale no. 1645 was lessthan normal whales, the thickness of the blubber was within the range for normal
whales. This indicate that it could feed with little difficulty by such an abnormal
mouth.
I wish to express deepest appreciation to Dr P. B. Best, Marine Mammal Laboratory, Sea Fisheries Branch, South Africa for his kind advice.
REFERENCES
NAKAMURA, K. 1968. Studies on the sperm whale with deformed lower jaw with special reference to its
feeding. Bull. Kanagawa Pref. Mus., 1: 13-27.
NAsu, K. 1958. Deformed lower jaw of sperm whale. Sci. Rep. Whales Res Inst., 13: 211-212.
0HSUMI, S. 1959. A deformed fin whale fetus. Sci. Rep. Whales Res. Inst., 14: 145-147.
SPAUL, E. A. 1964. Deformity in the lower jaw of the sperm whale (Physeter catodon). Proc. :(ool. Soc. Lond.,

142 (3): 391-395.

Sci. Rep. Whales Res. Inst.,
No. 31, 1979