Reversal of the Direction of Mucus-Flow on the Ciliated Pharynx of a Sea Anemone

Abstract

The ciliated pharynx of the sea anemone Calliactisparasitica (Couch) acts as an independent selective barrier for the admission of material to the coelenteron. Direct observation shows that reversal of the direction of the mucus flow is effected by a reversal of the direction of the ciliary power-stroke. Reversal of the power-stroke can only be stimulated by food juices applied directly to the pharynx and it is not propagated to unstimulated areas. Reversal of the power-stroke occurs in the absence of all recordable electrical activity. This is one of the few examples among the Metazoa where it has been shown that a modification of the ciliary beating pattern is unlikely to be controlled by an electrical conduction system.