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Locomotion pattern and trunk musculoskeletal architecture among Urodela.

Omura A, Ejima KI, Honda K, Anzai W, Taguchi Y, Koyabu D, Endo H - Acta Zool (2014)

Bottom Line: Our results suggest that larger lateral hypaxial muscles function for lateral bending during underwater locomotion in aquatic species.The more aquatic species possessed a more horizontal prezygapophyseal angle for more flexible lateral locomotion.Thus, we conclude trunk structure in urodeles differs clearly according to their locomotive modes.

View Article: PubMed Central - PubMed

Affiliation: Graduate School of Agricultural and Life Sciences, The University Museum, The University of Tokyo 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan ; The University Museum, The University of Tokyo 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.

ABSTRACT

We comparatively examined the trunk musculature and prezygapophyseal angle of mid-trunk vertebra in eight urodele species with different locomotive modes (aquatic Siren intermedia, Amphiuma tridactylum, Necturus maculosus and Andrias japonicus; semi-aquatic Cynops pyrrhogaster, Cynops ensicauda; and terrestrial Hynobius nigrescens, Hynobius lichenatus and Ambystoma tigrinum). We found that the more terrestrial species were characterized by larger dorsal and abdominal muscle weight ratios compared with those of the more aquatic species, whereas muscle ratios of the lateral hypaxial musculature were larger in the more aquatic species. The lateral hypaxial muscles were thicker in the more aquatic species, whereas the M. rectus abdominis was more differentiated in the more terrestrial species. Our results suggest that larger lateral hypaxial muscles function for lateral bending during underwater locomotion in aquatic species. Larger dorsalis and abdominal muscles facilitate resistance against sagittal extension of the trunk, stabilization and support of the ventral contour line against gravity in terrestrial species. The more aquatic species possessed a more horizontal prezygapophyseal angle for more flexible lateral locomotion. In contrast, the more terrestrial species have an increasingly vertical prezygapophyseal angle to provide stronger column support against gravity. Thus, we conclude trunk structure in urodeles differs clearly according to their locomotive modes.

No MeSH data available.


Related in: MedlinePlus

—Frontal view of mid-trunk vertebra. —A. μ-CT scanned image of vertebra of Siren intermedia. —B. Frontal view of mid-trunk vertebra of Siren intermedia for measuring prezygapophyseal angle. —a. Prezygapophyseal angle. Scale bar = 1 cm.
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fig02: —Frontal view of mid-trunk vertebra. —A. μ-CT scanned image of vertebra of Siren intermedia. —B. Frontal view of mid-trunk vertebra of Siren intermedia for measuring prezygapophyseal angle. —a. Prezygapophyseal angle. Scale bar = 1 cm.

Mentions: Eight species of adult salamanders representing seven families and three different habitats (aquatic, semi-aquatic and terrestrial) were used (Table 2). The mid-trunk vertebrae were scanned using a micro-CT (R_mCT®; Rigaku Co., Tokyo, Japan) at the Department of Oral and Maxillofacial Radiology, Nihon University School of Dentistry, Tokyo, Japan, and I-View-R (Rigaku Co.) was used for image processing. The prezygapophyseal angle was measured on scanned images (Fig.2). Here, this angle is defined as the one between the articular surface on the prezygapophysis and the horizontal plane measured on images taken perpendicular to the long axis of the vertebra. The prezygapophyseal angle was also measured on skeletal specimens of large individual of Amphiuma tridactylum and Andrias japonicus. Homogeneity of variances and means of each item between species were confirmed by ANOVA and Tukey's test.


Locomotion pattern and trunk musculoskeletal architecture among Urodela.

Omura A, Ejima KI, Honda K, Anzai W, Taguchi Y, Koyabu D, Endo H - Acta Zool (2014)

—Frontal view of mid-trunk vertebra. —A. μ-CT scanned image of vertebra of Siren intermedia. —B. Frontal view of mid-trunk vertebra of Siren intermedia for measuring prezygapophyseal angle. —a. Prezygapophyseal angle. Scale bar = 1 cm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4402012&req=5

fig02: —Frontal view of mid-trunk vertebra. —A. μ-CT scanned image of vertebra of Siren intermedia. —B. Frontal view of mid-trunk vertebra of Siren intermedia for measuring prezygapophyseal angle. —a. Prezygapophyseal angle. Scale bar = 1 cm.
Mentions: Eight species of adult salamanders representing seven families and three different habitats (aquatic, semi-aquatic and terrestrial) were used (Table 2). The mid-trunk vertebrae were scanned using a micro-CT (R_mCT®; Rigaku Co., Tokyo, Japan) at the Department of Oral and Maxillofacial Radiology, Nihon University School of Dentistry, Tokyo, Japan, and I-View-R (Rigaku Co.) was used for image processing. The prezygapophyseal angle was measured on scanned images (Fig.2). Here, this angle is defined as the one between the articular surface on the prezygapophysis and the horizontal plane measured on images taken perpendicular to the long axis of the vertebra. The prezygapophyseal angle was also measured on skeletal specimens of large individual of Amphiuma tridactylum and Andrias japonicus. Homogeneity of variances and means of each item between species were confirmed by ANOVA and Tukey's test.

Bottom Line: Our results suggest that larger lateral hypaxial muscles function for lateral bending during underwater locomotion in aquatic species.The more aquatic species possessed a more horizontal prezygapophyseal angle for more flexible lateral locomotion.Thus, we conclude trunk structure in urodeles differs clearly according to their locomotive modes.

View Article: PubMed Central - PubMed

Affiliation: Graduate School of Agricultural and Life Sciences, The University Museum, The University of Tokyo 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan ; The University Museum, The University of Tokyo 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.

ABSTRACT

We comparatively examined the trunk musculature and prezygapophyseal angle of mid-trunk vertebra in eight urodele species with different locomotive modes (aquatic Siren intermedia, Amphiuma tridactylum, Necturus maculosus and Andrias japonicus; semi-aquatic Cynops pyrrhogaster, Cynops ensicauda; and terrestrial Hynobius nigrescens, Hynobius lichenatus and Ambystoma tigrinum). We found that the more terrestrial species were characterized by larger dorsal and abdominal muscle weight ratios compared with those of the more aquatic species, whereas muscle ratios of the lateral hypaxial musculature were larger in the more aquatic species. The lateral hypaxial muscles were thicker in the more aquatic species, whereas the M. rectus abdominis was more differentiated in the more terrestrial species. Our results suggest that larger lateral hypaxial muscles function for lateral bending during underwater locomotion in aquatic species. Larger dorsalis and abdominal muscles facilitate resistance against sagittal extension of the trunk, stabilization and support of the ventral contour line against gravity in terrestrial species. The more aquatic species possessed a more horizontal prezygapophyseal angle for more flexible lateral locomotion. In contrast, the more terrestrial species have an increasingly vertical prezygapophyseal angle to provide stronger column support against gravity. Thus, we conclude trunk structure in urodeles differs clearly according to their locomotive modes.

No MeSH data available.


Related in: MedlinePlus