Insulin-like peptides (ILPs) have been proved to exist extensively in invertebrates and play critical roles in regulating growth, metabolism and reproduction.ILP signaling system has been well defined in insects, with all key components homologous with vertebrate IGF signaling;however, counterparts of IGF binding proteins (IGFBPs) in vertebrates are not included in this system because of lacking sufficient researches in the related aspect.The present study firstly reports the identification of three kinds of invertebrate IGF binding (IB) domain-containing protein genes from the mud crab Scylla paramamosain.