Kinematics of the ribbon fin in hovering and swimming of the electric ghost knifefish
Kinematics of the ribbon fin in hovering and swimming of the electric ghost knifefish
By Ricardo Ruiz-Torres, Oscar M. Curet, George V. Lauder, and Malcolm A. MacIver
Journal of Experimental Biology (2013)
Abstract Paper

Ricardo Ruiz-Torres

Northwestern University

United States

Coder Page  

Malcolm A. MacIver

Northwestern University

United States

Coder Page  

These programs implement all the kinematics analysis and visualizations for the paper. In addition, there is a coupled CPG model that is used to generate the modeling results, and a GUI for experimenting with this model. Original high speed video files as well as the motion capture data of the ribbon fin edge is included.
Created
November 10, 2012
Software:
Matlab 2012
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Last update
February 19, 2013
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7
Abstract
Weakly electric knifefish are exceptionally maneuverable swimmers. In prior work, we have shown that they are able to move their entire body omnidirectionally so that they can rapidly reach prey up to several centimeters away. Consequently, in addition to being a focus of efforts to understand the neural basis of sensory signal processing in vertebrates, knifefish are increasingly the subject of biomechanical analysis to understand the coupling of signal acquisition and biomechanics. Here, we focus on a key subset of the knifefish's omnidirectional mechanical abilities: hovering in place, and swimming forward at variable speed. Using high-speed video and a markerless motion capture system to capture fin position, we show that hovering is achieved by generating two traveling waves, one from the caudal edge of the fin and one from the rostral edge, moving toward each other. These two traveling waves overlap at a nodal point near the center of the fin, cancelling fore-aft propulsion. During forward swimming at low velocities, the caudal region of the fin continues to have counter-propagating waves, directly retarding forward movement. The gait transition from hovering to forward swimming is accompanied by a shift in the nodal point toward the caudal end of the fin. While frequency varies significantly to increase speed at low velocities, beyond approximately one body length per second, the frequency stays near 10 Hz, and amplitude modulation becomes more prominent. A coupled central pattern generator model is able to reproduce qualitative features of fin motion and suggest hypotheses regarding the fin's neural control.
Ruiz-Torres, R., O. M. Curet, G. V. Lauder, and M. A. MacIver, "Kinematics of the ribbon fin in hovering and swimming of the electric ghost knifefish", Journal of Experimental Biology , 1.
Coders:
  • Ricardo Ruiz-Torres

    Northwestern University

    United States

  • Malcolm A. MacIver

    Northwestern University

    United States

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Kinematics of the ribbon fin in hovering and swimming of the electric ghost knifefish

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