Particular attention is given to the crustacean hyperglycemic hormone (CHH), to the gonad inhibiting (GIH) and stimulating hormone (GSH), to the moult inhibiting hormone (MIH) and to the peptidergic factors related to some hormones from vertebrates and insects. The interactions of these factors as well as the coordination with biogenic amines and steroids in the control of the metabolism, reproduction and moulting are postulated.