Evidence for Endocrine Disruption in Invertebrates Matthias Oetken, Jean Bachmann, Ulrike Schulte-Oehlmann, and Jörg Oehlmann Department of Ecology and Evolution – Ecotoxicology, Johann Wolfgang Goethe University Frankfurt, D-60054 Frankfurt am Main, Germany The issue of endocrine disruption (ED) in invertebrates has generated remarkably little interest in the past compared to research with aquatic vertebrates in this area. However, with more than 95% of all known species in the animal kingdom, invertebrates constitute a very important part of the global biodiversity with key species for the structure and function of aquatic and terrestrial ecosystems. Despite the fact that ED in invertebrates has been investigated on a smaller scale than in vertebrates, invertebrates provide some of the best documented examples for deleterious effects in wildlife populations following an exposure to endocrine-active substances. The article provides an overview of the diversity in endocrine systems of invertebrates. The principal susceptibility of invertebrates to endocrine-active compounds is demonstrated with the case studies of tributyltin effects in mollusks and of insect growth regulators, the latter as purposely synthesized endocrine disrupters. The additional evidence for ED in invertebrates from laboratory and field studies is summarized as an update and amendment of the EDIETA report from 1998. Finally, conclusions about the scale and implications of the observed effects are drawn and research needs defined. Key Words: Endocrine disruption, Invertebrates, Annelids, Crustaceans, Echinoderms, Insects, Mollusks, Porifera, Rotatoria, Tunicata, Tributyltin, Insect growth regulators. © 2004 Elsevier Inc. I. Introduction All animal phyla use chemical signaling systems to regulate biological functions. Because hormonal control of developmental processes such as growth, sexual differentiation and reproduction is such a widespread and International review of Cytology, Vol. 236 1 Copyright 2004, Elsevier Inc. 0074-7696/04 $35.00 All rights reserved.