ABSTRACT
Perch Parasites Jasminca Behrmann-Godel1,* and Alexander Brinker2
1 Limnological Institute, University of Konstanz, Mainaustrasse 252, 78457 Konstanz, Germany. 2 Fisheries Research Station Baden-Württemberg, Argenweg 50/1, 88085 Langenargen, Germany. E-mail: Alexander.Brinker@lazbw.bwl.de * Corresponding author: Jasminca.Behrmann@uni-konstanz.de
Almost every major group of organisms including viruses, bacteria, protists, higher metazoans, fungi, plants and mammals has parasitic members and there are indications that species with at least one parasitic phase in their life history may actually outnumber non-parasites. Some parasites develop directly on or in their host, while others have extremely complex life cycles involving a sequence of obligate hosts infected at different stages of development. For a glossary of important parasitological terms used in this chapter, see the Infobox. From a parasite’s point of view, the host can be seen as its environment, providing a number of distinct habitats for colonization (Bush et al. 1977). The many different ways in which parasites infect their hosts are mostly specifi c to parasite species and/or life cycle stage. Infection may be direct as in most trematode cercariae, which penetrate the host’s skin. However parasites can also be transmitted actively by vectors or indirectly via the food chain-for example
Infobox: Parasitological terminology
Defi nition of Parasitism:
Parasites are organisms that benefi t at the expense of another organism belonging to another species, called the host, mostly by trophic exploitation.
