Mechanisms of locomotion in the polychaete, Harmothoë

Abstract

• 1.

  1. During forward walking parapodial stepping and s waves occur; the two can be separated by sectioning appropriate segmental nerves.

• 2.

  2. Thirty cycles of stepping begin at the pygidium/min and move rostrally over 3–10 segments/sec.

• 3.

  3. Ipsi- and contralateral cycles are about 180° out of phase, a phase lag developing during acceleration.

• 4.

  4. Pacemakers are in each nerve cord segment; the frequency is determined by dominant posterior pacemakers.

• 5.

  5. Propagation of locomotory cycles depends upon and intact cord and intact parapodial nerves and ganglia in each segment, and does not require the integrity of other segmental nerves, setal receptor input nor peripheral reflexes.