Neuropeptides have been found in nervous central or immune systems of Annelids. Since these signaling molecules are found free in the hemolymph, they are considered as hormones. Hormonal processes along with enzymatic processing similar to that found in vertebrates occur in annelids. Furthermore, amino acid sequence determination of annelids precursor gene products reveals the presence of the respective peptides that exhibit high sequence identity to their mammalian counterparts. Nevertheless, specific neuropeptides to annelids or invertebrates have also been in these animals. These peptides are flanked by potential proteolytic signal sites for the various known enzymes confirming that annelids neuropeptide precursors are processed in a similar manner to that described in mammals i.e. implicating prohormone convertase enzymes.