Slows down the inactivation process of TTX-sensitive voltage-gated sodium channels (Nav) (PubMed:16814340). Has a strong crab-paralyzing activity (PubMed:16814340). The minimum lethal dose against crabs is 7.9 mg/kg (Ref.1). LD(50) is 1 ug/kg by injection at the junction between the body and the walking leg of crabs. LD(100) is 5 ug/g when injected into fly larvae (M.domestica). Belongs to the sea anemone sodium channel inhibitory toxin family. Type I subfamily.