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Journal of Experimental Biology 51,387-396 (1969)
Published by Company of Biologists 1969

Co-Ordination of Pedal-Disk Detachment in the Sea Anemone Calliactis Parasitica

I. D. MCFARLANE ¹

¹ Department of Zoology, University of Bristol, Bristol 8

1. Electrical activity has been recorded from the sphincter region of Calliactis parasitica during the behavioural sequence in which the anemone detaches from the substrate and attaches to a Buccinum shell. The ectodermal slow-conduction system (SS1) fires repetitively, the majority of observed pulses occurring in the period prior to detachment (a typical example is 25 SS1pulses at an average frequency of 1 pulse/7 sec.). Shell-tentacle contact is essential for stimulation of SS1activity.

2. Mechanical stimulation of the column excites the SS1, and 30 stimuli at a frequency of about one shock/5 sec. give pedal disk detachment.

3. Electrical stimulation of the ectoderm excites the SS1and about 30 stimuli at frequencies between one shock/3 sec. and one shock/9 sec. produce detachment. Detachment and the SS1 have an identical stimulus threshold. It is concluded that detachment is co-ordinated by the SS1.