Dactyl Sensory Influences on Rock Lobster Locomotion: II. ROLE IN INTERLEG COORDINATION

ABSTRACT The effects of cyclic electrical stimulation of the dactyl sensory nerve (DN) on the walking pattern of rock lobsters were examined at the two crucial points within the step cycle: the anterior extreme position (AEP) and the posterior extreme position (PEP). Stimulation during the occurrence of the PEP affected neither the movement pattern of the stimulated leg itself nor that of the ipsilateral adjacent legs. Stimulation of the same intensity during the occurrence of the AEP interrupted the oscillation of the stimulated leg and affected the phase relationships of the ipsilateral adjacent legs. The possibility that indirect influences were mediated by coupling to the substratum can be excluded. Neuronal connections may therefore exist between the funnel canal organs (FCO) of a single leg and the motor output of the adjacent legs. The discussion deals with whether the described channels alone are able to fulfil the requirements of a ‘coordinating mechanism’ as described in the literature.