Biomechanics of salamander locomotion

2005 2005

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Abstract (summary)

Most larval and permanently aquatic salamanders use undulatory swimming as their primary mode of steady aquatic locomotion. These swimming movements are powered by the segmented axial musculature. The hypaxial region of each segment consists of distinct muscle layers, which have a simple planar geometry and have varying architectural features. In an aquatic salamander Siren lacertina, the morphological features of the lateral hypaxial layers allow the shortening of muscle fibers to be amplified during contraction. The angled muscle fibers in these layers function to allow fiber shortening to be accompanied by substantial rotation of muscle fibers during contraction. The connective tissue sheets separating adjacent muscle segments (myosepta), allow the segment to bulge in a way that further amplifies muscle fiber rotation. The combined effect of architectural and moment arm variation ensures that muscle fibers from different layers undergo similar shortening patterns during swimming to allow for the generation of optimal tension during locomotion.

In addition to steady swimming many salamanders respond to a predatory stimulus by performing a “C-start” aquatic escape response. This unsteady maneuver involves two kinematic stages, which function to propel the salamander away from the perceived threat. During metamorphosis, the tailfin of salamanders is resorbed and is thought to result in a substantial decrease in escape performance. However, in a stream salamander Eurycea bislineata , adults spend significant time in the water and behaviorally compensate for metamorphic changes in tail morphology by increasing the amplitude of escape responses.

Aquatic locomotion in salamanders is not limited to axial swimming. Some salamanders also utilize their limbs to move along the substrate at slow speeds, while submerged. Structures used during aquatic walking face dramatically different mechanical loads compared to limbs used on land. The greater hydrodynamic resistance associated with water lowers the effective weight and can act to stabilize an organism throughout its gait. Therefore structures, such as the reduced limbs of S. lacertina, which would be considered ineffective on land, can be fully functional during aquatic walking.

Indexing (details)

Anatomy & physiology;
0433: Anatomy & physiology
0433: Animals
0472: Zoology
0287: Anatomy & physiology
0786: Biophysics
Identifier / keyword
Biological sciences; Biomechanics; Locomotion; Salamander; Swimming
Biomechanics of salamander locomotion
Azizi, Emanuel
Number of pages
Publication year
Degree date
School code
DAI-B 66/06, Dissertation Abstracts International
Place of publication
Ann Arbor
Country of publication
United States
9780542197406, 0542197405
Brainerd, Elizabeth L.
University of Massachusetts Amherst
University location
United States -- Massachusetts
Source type
Dissertations & Theses
Document type
Dissertation/thesis number
ProQuest document ID
Database copyright ProQuest LLC; ProQuest does not claim copyright in the individual underlying works.
Document URL
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