Binds specifically to voltage-gated sodium channels (Nav) and delays their inactivation during signal transduction (when tested on the soma membrane of a crustacean neuron). Has also been observed to affect the activation of the sodium current. Does not have effect on potassium or calcium currents with concentrations up to 5 uM (PubMed:2409523). Is inactive at excitable membranes of frog (Inferred fromPubMed:2409523). Belongs to the sea anemone sodium channel inhibitory toxin family. Type I subfamily. Opinions are divided on whether Anemonia viridis (Forsskal, 1775) and Anemonia sulcata (Pennant, 1777) are separate species.