Effects of Removal of Muscle Receptor Organ Input on the Temporal Structure of Non-Giant Swimming Cycles in the Crayfish,Cherax Destructor

Most studies of the muscle receptor organs (MROs) of decapod crustaceans have focused on their role in local reflex loops. This may not be their only function. We examine their involvement in the regulation of non-giant swimming cycles by removing stretch receptor (SR) input from the MROs in abdominal segments 2-5 of the crayfish Cherax destructor. SR input was left intact in two control groups, one of which had sham surgery and the other no surgery at all. We recorded electromyograms (EMGs) from selected uropod muscles during tailflipping in sequences of non-giant swimming in tethered animals. The removal of SR input had a significant effect. The opener muscle period was shorter in the experimental group than in either of the control groups. This suggests that by using SR afference, crayfish sacrifice speed for increased control of the swimming movement.