This venom insulin, from a fish-hunting cone snail, facilitates prey capture by rapidly inducing hypoglycemic shock. It is one of the smallest known insulin found in nature and lacks the C-terminal segment of the B chain that, in human insulin, mediates engagement of the insulin receptor (INSR) and assembly of the hormone's hexameric storage form. Despite lacking this segment, it both binds and activates human insulin receptor (long isoform (HIR-B)) with a moderate potency (EC(50)=30.45 nM). In vivo, intraperitoneal injection of this peptide into zebrafish lowers blood glucose with a lower potency than human insulin. In addition, when applied to water, this peptide reduces overall locomotor activity of zebrafish larvae, observed as a significant decrease in the percentage of time spent swimming and movement frequency. When tested on a mouse model of diabetes, this insulin also lowers blood glucose with a 20-fold lower potency than human insulin