Spontaneous Electrical Activity in the Sea Anemone Calliactis Parasitica

Activity in the three known conduction systems in Calliactis parasitica (nerve net, SS 1, SS 2) has been monitored for periods up to 2 h. The ectodermal slow system (SS 1) shows irregular activity and many of the observed spontaneous pulses may in fact result from undetected external stimuli. The SS 2 shows rhythmic changes in frequency (approximate range 0·2–7·5 pulses/min.) During periods of low-frequency SS 2 activity a short (up to 10 pulses), high-frequency (up to 15/min) burst of activity in the through-conducting nerve net is seen. A slow contraction of the sphincter muscle is often seen after a nerve net burst.