Salamander locomotion as a standing wave

[bcrowell]

I recently came across a couple of very cool papers about animal locomotion:

Collins and Stewart, "Symmetry-breaking bifurcation: A possible mechanism for 2:1 frequency-locking in animal locomotion," J. Math. Biol. (1992) 30:827-838

Collins and Stewart, "Coupled Nonlinear Oscillators and the Symmetries of Animal Gaits," J. Nonlinear Sci. Vol. 3: pp. 349-392 (1993)

PDFs can be found by googling. On p. 34 of the second one is a nifty example that I thought would be of interest to students in the kind of survey course that biology majors have to take. As a salamander crawls, its body wiggles in a standing-wave pattern. A dogfish makes a traveling wave. I thought the salamander example was cool enough that I created a drawing for my online textbook http://www.lightandmatter.com/lm/ (section 20.4).

 

[A.T.]

Snake locomotion is also interesting in terms of waves:
http://www.pnas.org/content/106/25/10081.full

 

[Helios]

Now if you look at millipedes walk, their legs seem to make waves.

 

[bcrowell]

Snake locomotion is also interesting in terms of waves:
http://www.pnas.org/content/106/25/10081.full

I just about died laughing when I read the procedure for the friction measurement.

As far as I know, most such examples (earthworms, dogfish, snakes) are traveling waves, not standing waves, and the standing-wave pattern of the salamander is unusual.

 

[A.T.]

and the standing-wave pattern of the salamander is unusual.

It seems to me that many lizards use this pattern:
http://prehistoricict.blogspot.de/2015/09/posture-is-everything.html

It reminds me of a "snake board", which maybe should be called "lizards board"