Metazoa

Abstract

Metazoa parasites are multicellular organisms where cells have differentiated into organised tissues and organs. These parasites may be found in all fish organ systems both in wild and in farmed salmonids, in fresh and sea water. Recently, parasites that would have been included as Protists are now considered metazoans, as the case of Myxozoa. The use of molecular tools are able to identify many Metazoan parasites and 12S ribosomal DNA primers have significant potential for metagenetic analysis, but should not detract or replace traditional histology to asses their impact on the host. In this book we have used the term infestation to represent ectoparasitic conditions and infection, as referring to those that are endoparasitic. This chapter will cover a selection of the many species of Metazoa that can be found in salmonids.