1. When on the surface of water, locusts (Schistocerca or Locusta) adopt a characteristic posture with the front legs pointing forwards and the middle and hind legs backwards.

  2. Swimming is accomplished by the rapid extension of both hind tibiae. The legs move at the same time and not alternately as they do in walking. The swimming strokes are repeated at 2–3 Hz and give the locust a forward velocity of some 13 cm s-1.

  3. The motor pattern that brings about the extension of the hind tibiae is described from extracellular recording in the tibial muscles during swimming. The tibia is first flexed and held flexed by spikes of the flexor motoneurones. Then the extensor motoneurones begin to spike so that there is a period when flexor and extensor motoneurones are both spiking. This leads to cocontraction of the muscles. The flexor motoneurones then stop, but the extensors continue, with the result that the tibia extends rapidly.

  4. The same basic motor pattern for the movement of the tibia is used by the locust in jumping, kicking and swimming.

© 1978 by Company of Biologists
1978
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