FMRFamide (H-Phe-Met-Arg-Phe-NH2) is a neuropeptide from a broad family of FMRFamide-related peptides (FaRPs) all sharing an -RFamide sequence at their C-terminus.

[2] Several FMRFamide related peptides are known, regulating various cellular functions and possessing pharmacological actions, such as anti-opiate effects.

[6] In invertebrates, the FMRFamide-related peptides are known to affect heart rate, blood pressure, gut motility, feeding behaviour and reproduction.

[7] Detection of this neuropeptide is important because its expression lays down the foundation of the CNS in the early stages of development in invertebrates.

This is, in part, due to the extensive studies done on the Planorbid and Lymnaeid families of pond snails.