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Comparative functional anatomy of hindlimb muscles and bones with reference to aquatic adaptation of the sea otter.

Mori K, Suzuki S, Koyabu D, Kimura J, Han SY, Endo H - J. Vet. Med. Sci. (2015)

Bottom Line: We compared muscle mass and bone measurements of five Mustelidae species: the sea otter, Eurasian river otter (Lutra lutra), American mink (Neovison vison), Japanese weasel (Mustela itatsi) and Siberian weasel (M. sibirica).The bundles of the gluteus superficialis muscle of E. lutris were fused with those of the tensor fasciae latae muscle and gluteofemoralis muscles, and they may play a role in femur abduction.These results suggest that E. lutris uses the abducted femur, medially rotated crus, eversion of the ankle and abducted fifth digit or extended interdigital web as a powerful propulsion generator.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan.

ABSTRACT
Although the sea otter (Enhydra lutris) is a complete aquatic species, spending its entire life in the ocean, it has been considered morphologically to be a semi-aquatic animal. This study aimed to clarify the unique hindlimb morphology and functional adaptations of E. lutris in comparison to other Mustelidae species. We compared muscle mass and bone measurements of five Mustelidae species: the sea otter, Eurasian river otter (Lutra lutra), American mink (Neovison vison), Japanese weasel (Mustela itatsi) and Siberian weasel (M. sibirica). In comparison with the other 4 species, E. lutris possessed significantly larger gluteus, popliteus and peroneus muscles, but smaller adductor and ischiopubic muscles. The popliteus muscle may act as a medial rotator of the crus, and the peroneus muscle may act as an abductor of the fifth toe and/or the pronator of the foot. The bundles of the gluteus superficialis muscle of E. lutris were fused with those of the tensor fasciae latae muscle and gluteofemoralis muscles, and they may play a role in femur abduction. These results suggest that E. lutris uses the abducted femur, medially rotated crus, eversion of the ankle and abducted fifth digit or extended interdigital web as a powerful propulsion generator. Therefore, we conclude that E. lutris is a complete aquatic animal, possessing differences in the proportions of the hindlimb muscles compared with those in other semi-aquatic and terrestrial mustelids.

No MeSH data available.


Related in: MedlinePlus

Plot of PC1 and PC2 scores of muscle masses for the five mustelid species. PC1; thefirst principal component. PC2; the second principal component. Numbers in parenthesesrepresent the percentage of the variation explained by the component. , Enhydra lutris., Lutra lutra., Neovisonvison. , Mustelaitatsi. ,Mustela sibirica. Filled symbols indicate mean values of eachspecies.
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fig_002: Plot of PC1 and PC2 scores of muscle masses for the five mustelid species. PC1; thefirst principal component. PC2; the second principal component. Numbers in parenthesesrepresent the percentage of the variation explained by the component. , Enhydra lutris., Lutra lutra., Neovisonvison. , Mustelaitatsi. ,Mustela sibirica. Filled symbols indicate mean values of eachspecies.

Mentions: PC1 accounted for 47.4% of the variance and primarily separated E. lutrisfrom the other species (Fig. 2Fig. 2.


Comparative functional anatomy of hindlimb muscles and bones with reference to aquatic adaptation of the sea otter.

Mori K, Suzuki S, Koyabu D, Kimura J, Han SY, Endo H - J. Vet. Med. Sci. (2015)

Plot of PC1 and PC2 scores of muscle masses for the five mustelid species. PC1; thefirst principal component. PC2; the second principal component. Numbers in parenthesesrepresent the percentage of the variation explained by the component. , Enhydra lutris., Lutra lutra., Neovisonvison. , Mustelaitatsi. ,Mustela sibirica. Filled symbols indicate mean values of eachspecies.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4478071&req=5

fig_002: Plot of PC1 and PC2 scores of muscle masses for the five mustelid species. PC1; thefirst principal component. PC2; the second principal component. Numbers in parenthesesrepresent the percentage of the variation explained by the component. , Enhydra lutris., Lutra lutra., Neovisonvison. , Mustelaitatsi. ,Mustela sibirica. Filled symbols indicate mean values of eachspecies.
Mentions: PC1 accounted for 47.4% of the variance and primarily separated E. lutrisfrom the other species (Fig. 2Fig. 2.

Bottom Line: We compared muscle mass and bone measurements of five Mustelidae species: the sea otter, Eurasian river otter (Lutra lutra), American mink (Neovison vison), Japanese weasel (Mustela itatsi) and Siberian weasel (M. sibirica).The bundles of the gluteus superficialis muscle of E. lutris were fused with those of the tensor fasciae latae muscle and gluteofemoralis muscles, and they may play a role in femur abduction.These results suggest that E. lutris uses the abducted femur, medially rotated crus, eversion of the ankle and abducted fifth digit or extended interdigital web as a powerful propulsion generator.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan.

ABSTRACT
Although the sea otter (Enhydra lutris) is a complete aquatic species, spending its entire life in the ocean, it has been considered morphologically to be a semi-aquatic animal. This study aimed to clarify the unique hindlimb morphology and functional adaptations of E. lutris in comparison to other Mustelidae species. We compared muscle mass and bone measurements of five Mustelidae species: the sea otter, Eurasian river otter (Lutra lutra), American mink (Neovison vison), Japanese weasel (Mustela itatsi) and Siberian weasel (M. sibirica). In comparison with the other 4 species, E. lutris possessed significantly larger gluteus, popliteus and peroneus muscles, but smaller adductor and ischiopubic muscles. The popliteus muscle may act as a medial rotator of the crus, and the peroneus muscle may act as an abductor of the fifth toe and/or the pronator of the foot. The bundles of the gluteus superficialis muscle of E. lutris were fused with those of the tensor fasciae latae muscle and gluteofemoralis muscles, and they may play a role in femur abduction. These results suggest that E. lutris uses the abducted femur, medially rotated crus, eversion of the ankle and abducted fifth digit or extended interdigital web as a powerful propulsion generator. Therefore, we conclude that E. lutris is a complete aquatic animal, possessing differences in the proportions of the hindlimb muscles compared with those in other semi-aquatic and terrestrial mustelids.

No MeSH data available.


Related in: MedlinePlus