The control of walking in the scorpion
Ablation of one walking leg from the scorpion does not diminish its ability to walk in a relatively stable and constant fashion (Fig. 1). Removal of one of the fourth legs results in maximal disturbance.
Subsequent to ablation of one walking leg, the posterior-anterior stepping sequence for alternate leg pairs is not absolute as it is for intact scorpions (Fig. 2, Fig. 3). However, the 4231 order remains the dominant gait.
Ablation of either leg 1 (Fig. 2) or leg 4 results in minimal reorganization of the remaining ipsilateral appendages.
Ablation of an internal leg, leg 3 for example (Fig. 3), results in ipsilateral phase shifts so that leg 2 and leg 1 step relatively later in the leg 4 cycle (Fig. 4). Such ipsilateral reorganization is proposed to contribute to overall stability.
Dual ablation preparations walk as predicated by the single ablation experiments. An intact tetrapod can be maintained as a functional unit and be used reciprocally with the two other legs (Fig. 6). It was also observed that the promotion durations were consistently shorter in the dual ablation preparations than in the intact scorpions (Fig. 7).
KeywordsPhase Shift Functional Unit Step Sequence Ablation Experiment Maximal Disturbance
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