Endocrinology of the Cnidaria: state of the art

In this article an overview is given on both non-peptide regulators and pep tide signalling compounds and on their role in physiological regulation. Th e term "endocrinology" is understood as the "biology of chemical mediation between cells", since the classical definition which involves hormones emit ted by defined glands and distributed by body fluids is not applicable in c nidarians. In this animal group the understanding of chemical regulation is underdeveloped due to the lack of knowledge of ligand / receptor pairs and of complete signalling cascades. However, during recent decades the isolat ion and identification of hundreds of putative biologically active peptides has renewed the interest of the community of biologists in cnidarian physi ology. In the near future, the evaluation of the corresponding action pathw ays by identification of ligand / receptor interactions, of synthesising ce lls, and of target cells will have considerable implications for our unders tanding of biological regulation by chemical signalling compounds in genera l.