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Sexual Dimorphism in Pelvic Bone Shape of the North Pacific Common Minke Whales (Balaenoptera acutorostrata)

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DOI: 10.4236/ojas.2016.62016    1,183 Downloads   1,394 Views  

ABSTRACT

Little is known about the morphology of the pelvic girdle of modern cetaceans, although many species have a vestigial pelvis (pelvic bone) and part of the hind limb bones inside the body. Previous studies have focused almost exclusively on hard tissues as well, despite the fact that the bones are comprised of cartilaginous tissue, especially in the case of femur. In the present study, we characterized the pelvic bones and searched for vestigial femurs among 43 North Pacific common minke whales (Balaenoptera acutorostrata), all of which were sexually mature individuals. The shape of the pelvic bones clearly differs depending on sex. Specifically, the pelvic bones of females were flat, but those of adult males consist of two types: one with a twisted caudal portion (Twisted type) and the other with a thickened caudal portion (Hypertrophied type). Those pelvic bone features in male are found only among North Pacific common minke whales. 98% of the individuals in this study had vestigial femur. The presence rate of vestigial femur may differ by subspecies. The shape of the pelvic and hind limb bones of modern cetaceans may vary between species and probably by region, at least at the Ocean basin scale.

Cite this paper

Miyakawa, N. , Kishiro, T. , Fujise, Y. , Nakamura, G. and Kato, H. (2016) Sexual Dimorphism in Pelvic Bone Shape of the North Pacific Common Minke Whales (Balaenoptera acutorostrata). Open Journal of Animal Sciences, 6, 131-136. doi: 10.4236/ojas.2016.62016.

References

[1] Heyerdahl Jr., T. (1973) Sexual Dimorphism and Age Criteria in the Pelvic Bones of the Minke Whale, Balaenoptera acutorostrata Lacepede. Norwegian Journal of Zoology, 21, 39-43.
[2] Bejder, L. and Hall, B.K. (2002) Limbs in Whales and Limblessness in Other Vertebrates: Mechanisms of Evolutionary and Developmental Transformation and Loss. Evolution & Development, 4, 445-458.
http://dx.doi.org/10.1046/j.1525-142X.2002.02033.x
[3] Hosokawa, H. (1951) On the Pelvic Cartilages of the Balaenoptera-Foetuses, with Remarks on the Specifical and Sexual Difference. Scientific Reports of the Whales Research Institute, 5, 5-15.
[4] Nakamura, G. and Kato, H. (2014) Osteological Characteristics of Gray Whales Eschrichtius robustus Collected from the Coast of Japan (1990-2005) and Possible Population Mixing with Eastern Gray Whales in the Western North Pacific. Mammalian Science, 54, 73-86.
[5] Miyakawa, N. and Kato, H. (2015) Morphology of Innominate Bones (Pelvic Bones) of Bryde’s Whales Balaenoptera edeni. Mammalian Science, 55, 1-10.
[6] Tajima, Y., Hayashi, Y. and Yamada, T.K. (2004) Comparative Anatomical Study on the Relationships between the Vestigial Pelvic Bones and the Surrounding Structures of Finless Porpoises (Neophocaena phocaenoides). Journal of Veterinary Medical Science, 66, 761-766.
http://dx.doi.org/10.1292/jvms.66.761
[7] Perrin, W.F. (1975) Variation of Spotted and Spinner Porpoise (Genus Stenella) in the Eastern Pacific Hawaii. Bulletin of the Scripps Institution of Oceanography, 21, 1-206.
[8] Ito, H. and Miyazaki, N. (1990) Skeletal Development of the Striped Dolphin (Stenella coeruleoalba) in Japanese Waters. Journal of Mammalogical Siciety of Japan, 14, 79-96.
[9] Yoshida, H., Shirakihara, M., Takemura, A. and Shirakihara, K. (1994) Development, Sexual Dimorphism, and Individual Variation in the Skeleton of the Finless Porpoise, Neophocaena phocaenoides, in the Coastal Waters of Western Kyusyu, Japan. Marine Mammal Science, 10, 266-282.
http://dx.doi.org/10.1111/j.1748-7692.1994.tb00482.x
[10] Galatius, A. (2005) Sexually Dimorphic Proportions of the Harbor Porpoise (Phocoena phocoena) Skeleton. Journal of Anatomy, 206,141-154.
http://dx.doi.org/10.1111/j.1469-7580.2005.00381.x
[11] Iris, C., Natalia, A.D., Lida, E.P., Federico, P., Guillermo, H.C. and Natalie, P.G. (2015) Sexual Dimorphism and Morphometric Relationship in Pelvic Bones of Commerson’s Dolphins (Cephalorhynchus c. commersonii) from Tierra del Fuego, Argentina. Marine Mammal Science, 31, 734-747.
http://dx.doi.org/10.1111/mms.12172
[12] Lönnberg, E. (1910) The Pelvic Bones of Some Cetacea. Arkiv För Zoologi, 7, 1-15.
[13] Arvy, L. (1979) The Abdominal Bones of Cetaceans. In: Pilleri, G., Ed., Investigations on Cetacea, Vol. 10, Brain Anatomy Institute, Berne, 215-227.
[14] Omura, H. (1980) Morphological Study of Pelvic Bones of the Minke Whale from the Antarctic. Scientific Reports of the Whales Research Institute, 32, 25-37.

  
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