Nervous Systems of Lower Animals as Models, With Particular Reference to Peptidergic Neurons in Gastropods

Abstract

The enormous diversity of animal life can only be understood from the intimate relationship of animals to their environment. The continuous adaptation to short- and long-term changes in the biotic and abiotic environment requires the continuous action of the nervous system. Therefore, it is not surprising that central and peripheral nervous systems show an enormous diversity in structure and arrangement. The nervous systems of only a relatively small number of invertebrates have been studied up to now. Interest for these systems in lower animals comes from two different backgrounds. First, there is the attitude of naturalists, which have a great curiosity about all animals. They analyze the functioning of the nervous system in relation to the activities of the species concerned. The second attitude is the selection of experimental animals based on the presence of advantageous characteristics for the study of particular problems, the results of which are expected to be of general importance.—biological problems. Such systems are called model systems. For the study of the organization of the nervous system in general, model systems of various invertebrates have been of great importance. The aim of this chapter is to present a short survey of these models. Particular attention will be given to the recent discovery of models for investigations of peptidergic systems. This is preceded by general information about the nervous systems of invertebrates.