Access

You are not currently logged in.

Access JSTOR through your library or other institution:

login

Log in through your institution.

Journal Article

The Importance of Body Stiffness in Undulatory Propulsion

John H. Long, Jr. and Karen S. Nipper
American Zoologist
Vol. 36, No. 6 (Dec., 1996), pp. 678-694
Published by: Oxford University Press
Stable URL: http://www.jstor.org/stable/3884006
Page Count: 17
Were these topics helpful?
See something inaccurate? Let us know!

Select the topics that are inaccurate.

  • Download ($42.00)
  • Subscribe ($19.50)
  • Add to My Lists
  • Cite this Item
The Importance of Body Stiffness in Undulatory Propulsion
Preview not available

Abstract

During steady swimming in fish, the dynamic form taken by the axial undulatory wave may depend on the bending stiffness of the body. Previous studies have suggested the hypothesis that fish use their muscles to modulate body stiffness. In order to expand the theoretical and experimental tools available for testing this hypothesis, we explored the relationship between body stiffness, muscle activity, and undulatory waveform in the mechanical context of dynamically bending beams. We propose that fish minimize the mechanical cost of bending by increasing their body stiffness, which would allow them to tune their body's natural frequency to match the tailbeat frequency at a given swimming speed. A review of the literature reveals that the form of the undulatory wave, as measured by propulsive wavelength, is highly variable within species, a result which calls into question the use of propulsive wavelength as a species-specific indicator of swimming mode. At the same time, the smallest wavelength within a species is inversely proportional to the number of vertebrae across taxa (r2 = 0.21). In order to determine if intact fish bodies are capable of increasing bending stiffness, we introduce a method for stimulating muscle in the body of a dead fish while it is being cyclically bent at physiological frequencies. The bending moment (N m) and angular displacement (radians) are measured during dynamic bending with and without muscle stimulation. Initial results from these whole-body work loops demonstrate that largemouth bass possess the capability to increase body stiffness by using their muscles to generate negative mechanical work.

Page Thumbnails

  • Thumbnail: Page 
678
    678
  • Thumbnail: Page 
679
    679
  • Thumbnail: Page 
680
    680
  • Thumbnail: Page 
681
    681
  • Thumbnail: Page 
682
    682
  • Thumbnail: Page 
683
    683
  • Thumbnail: Page 
684
    684
  • Thumbnail: Page 
685
    685
  • Thumbnail: Page 
686
    686
  • Thumbnail: Page 
687
    687
  • Thumbnail: Page 
688
    688
  • Thumbnail: Page 
689
    689
  • Thumbnail: Page 
690
    690
  • Thumbnail: Page 
691
    691
  • Thumbnail: Page 
692
    692
  • Thumbnail: Page 
693
    693
  • Thumbnail: Page 
694
    694