Binds specifically to voltage-gated sodium channels (Nav) (site 3), thereby delaying their inactivation. Has a strong effect on crustaceans and insects (DmNav1) and a weaker effect on mammals. This toxin is highly potent at mammalian Nav1.1/SCN1A (EC(50)=6.01 nM) and Nav1.2/SCN2A (EC(50)=7.88 nM) (PubMed:15169781). It has also great activity on Nav1.5/SCN5A (EC(50)=49.05 nM), Nav1.4/SCN4A (EC(50)=109.49 nM) and Nav1.6/SCN8A (EC(50)=about 180 nM) and is less potent on Nav1.3/SCN3A (EC(50)=759.22 nM) (when measured as the increase in the slow component) (PubMed:15169781). 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.