Myxozoa - Morphology, Molecules and Myths

Myxozoa are completely endoparasitic animals with complex life-cycles, involving alternation between a vertebrate and an invertebrate host. They are highly aberrant and simple in their morphology lacking important metazoan traits like gonads, gametes, intestinal tracts, nerve cells, and also some basic eukaryote cytological features. For most of the time that myxozoans have been recognised, their phylogenetic affinities were elusive. The recent insights that myxozoans are a subtaxon of Cnidaria and morphologically more diverse than previously acknowledged, makes this group particularly interesting for studies of body plan evolution and secondary reduction of morphological characters.

Despite both their impressive radiation with more than 2,200 described species – almost one fifth of present-day cnidarian species diversity – and their considerable economic and ecological impact as fish parasites, myxozoans have remained understudied from a comparative zoological perspective. In this talk I will summarise recent advances in the knowledge on biology, evolution, and development of this bizarre animal group. I will present examples how recent advances in microscopic and molecular biological methods can help to elucidate patterns of morphological evolution in non-model-species and how the study of neglected taxa is invaluable for insights into the diversity of animal body plans.