Coelenterata Hormone-Nerve Interaction

Oxytocin/vasopressin-like Immunoreactivity ... in Hydra (PubMed)$=relatedarticles&logdbfrom=pubmed 

    Abstract only.  "Nerve cells have been found in hydra, which react with antisera to oxytocin, vasopressin and mesotocin. These nerve cells have a high density in the ectoderm of basal disk and tentacles,"  However, "...the antigenic determinant of hydra is not oxytocin or vasopressin. The presence of oxytocin/vasopressin-like material in coelenterates, shows that this family of peptides is of great antiquity."