Most benthic marine invertebrates begin life with a mobile larval phase that must undergo metamorphosis to obtain the adult form. For many (non-arthropod) invertebrates this process involves an external stimulant that induces an extremely rapid neurogenic sequence of events. For the cosmopolitan marine worm Hydroides elegans the external cue originates with certain biofilm bacteria. One such bacterium, Pseudoalteromonas luteoviolacea, induces metamorphosis in larvae of H. elegans with complex clusters of organelles known as tailocins. Tailocins have been demonstrated to kill other bacteria by puncturing their cell membrane and causing a lethal ion flux. We hypothesize a similar mechanism for induction of metamorphosis: that puncturing the membrane of a sensory cell is sufficient to stimulate metamorphosis. To test this hypothesis, we aimed to (1) chemically create holes in membranes larvae of H. elegans with saponins and (2) inhibit metamorphosis in larvae of H. elegans with low sodium artificial seawater. Low sodium artificial seawater should inhibit the formation of action potentials across excitatory membranes and prevent larvae from responding to inductive cues. Using 1 h pulse exposures, larvae were subjected to both natural and artificial cues in the presence of low sodium artificial seawater and then allowed to recover in sterile seawater. We found that metamorphosis was significantly reduced in the presence of low sodium seawater, suggesting that the generation of action potentials play an important role in the induction of metamorphosis in the larvae of H. elegans.