Introduction

Abstract

Abstract One of the most important characters of metazoans is the presence of a nervous system and the ability to react and act to external stimuli. Therefore, the nervous system has always received special attention by biologists. As there have been significant advances in methods and strucural knowledge since the important books by Hanström in 1928 and by Bullock and Horridge in 1965, it seems appropriate to summarize the current information on the nervous system of invertebrates. Since these last reviews methodological advances have been made mainly through the use of immunohistochemistry and confocal laser scanning microscopy, transmission electron microscopy as well as serial sectioning tomography, however, further methods are currently being explored. This contribution sets out to provide a systematic overview over the organization of the nervous systems in invertebrates integrating the latest findings. In a phylogenetic context, these new data provide new insights into the evolution of metazoan nervous systems. The general overview is supplemented by seletced chapters that explore the function of the nervous system.